Repository: 89luca89/pakkero Branch: master Commit: 86322011b06e Files: 13 Total size: 118.1 KB Directory structure: gitextract_h2o9k04m/ ├── .gitignore ├── Dockerfile ├── LICENSE ├── Makefile ├── README.md ├── data/ │ └── launcher.go ├── go.mod ├── go.sum ├── internal/ │ └── pakkero/ │ ├── encryption.go │ ├── obfuscation.go │ ├── pakkero.go │ └── utilities.go └── main.go ================================================ FILE CONTENTS ================================================ ================================================ FILE: .gitignore ================================================ PackNGo test dist __* tags TODO.md ================================================ FILE: Dockerfile ================================================ FROM golang:alpine ENV CGO_ENABLED=0 ENV GO111MODULE=off RUN apk add --update-cache upx git make binutils coreutils \ && rm -rf /var/cache/apk/* RUN upx --version RUN go version RUN go get -d -v github.com/89luca89/pakkero WORKDIR $GOPATH/src/github.com/89luca89/pakkero RUN make RUN ./dist/pakkero -v ENTRYPOINT ["./dist/pakkero"] ================================================ FILE: LICENSE ================================================ GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007 Copyright (C) 2007 Free Software Foundation, Inc. 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The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an "about box". You should also get your employer (if you work as a programmer) or school, if any, to sign a "copyright disclaimer" for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see . The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read . ================================================ FILE: Makefile ================================================ all: go build -i \ -gcflags="-N" \ -gcflags="-nolocalimports" \ -gcflags="-pack" \ -gcflags="-trimpath=." \ -asmflags="-trimpath=." \ -gcflags="-trimpath=$$GOPATH/src/" \ -asmflags="-trimpath=$$GOPATH/src/" \ -ldflags="-X github.com/89luca89/pakkero/internal/pakkero.LauncherStub=$$(base64 -w0 data/launcher.go) -s" \ -o dist/pakkero; strip \ -sxX \ --remove-section=.bss \ --remove-section=.comment \ --remove-section=.eh_frame \ --remove-section=.eh_frame_hdr \ --remove-section=.fini \ --remove-section=.fini_array \ --remove-section=.gnu.build.attributes \ --remove-section=.gnu.hash \ --remove-section=.gnu.version \ --remove-section=.got \ --remove-section=.note.ABI-tag \ --remove-section=.note.gnu.build-id \ --remove-section=.shstrtab \ --remove-section=.typelink \ dist/pakkero; clean: rm -rf dist/; go build -i \ -gcflags="-N" \ -gcflags="-nolocalimports" \ -gcflags="-pack" \ -gcflags="-trimpath=." \ -asmflags="-trimpath=." \ -gcflags="-trimpath=$$GOPATH/src/" \ -asmflags="-trimpath=$$GOPATH/src/" \ -ldflags="-X github.com/89luca89/pakkero/internal/pakkero.LauncherStub=$$(base64 -w0 data/launcher.go) -s" \ -o dist/pakkero; strip \ -sxXwSgd \ --remove-section=.bss \ --remove-section=.comment \ --remove-section=.eh_frame \ --remove-section=.eh_frame_hdr \ --remove-section=.fini \ --remove-section=.fini_array \ --remove-section=.gnu.build.attributes \ --remove-section=.gnu.hash \ --remove-section=.gnu.version \ --remove-section=.got \ --remove-section=.note.ABI-tag \ --remove-section=.note.gnu.build-id \ --remove-section=.shstrtab \ --remove-section=.typelink \ dist/pakkero test: clean dist/pakkero \ -file /usr/bin/echo -c \ -o /tmp/test.enc \ -offset 2850000 \ -enable-stdout \ -register-dep /usr/bin/bash; sync; sh -c "/tmp/test.enc test" ================================================ FILE: README.md ================================================ # Pakkero Credit: [alegrey91](https://github.com/alegrey91) for the logo! Thanks! [![Go Report Card](https://goreportcard.com/badge/github.com/89luca89/pakkero)](https://goreportcard.com/report/github.com/89luca89/pakkero) [![GPLv3 license](https://img.shields.io/badge/License-GPLv3-blue.svg)](http://perso.crans.org/besson/LICENSE.html) [![FOSSA Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2F89luca89%2Fpakkero.svg?type=small)](https://app.fossa.com/projects/git%2Bgithub.com%2F89luca89%2Fpakkero?ref=badge_small) ## Introduction **Pakkero** is a binary packer written in Go made for fun and educational purpose. Its main goal is to take in input a program file (elf binary, script, even appimage) and compress it, protect it from tampering and intrusion. It is not recommended for very small files as the launcher itself can vary from ~700kb to ~1.7mb depending on compression. On files above 2.6mb there is gain, else the resulting binary is larger than the original: ``` base-bin 1.2M -> 1.6M smaller-bin 2.4M -> 2.3M small-bin 3.7M -> 3.0M medium-bin 25M -> 16M big-bin 148M -> 88M ``` With compression disabled, all resulting file size are ~1mb higher, making it suitable for 5+mb files. #### How compares to UPX? Tested with a 24mb binary file (I didn't have a big project handy so I just concatenated a bunch of programs from `/usr/bin/` to make one big elf) became: - 12mb using `upx -9` - 13mb using `pakkero -c` - 14mb using `pakkero` without compression ## Install If you have a [Go](https://golang.org/) environment ready to go, it's as easy as: ```bash go get github.com/89luca89/pakkero ``` Once you retrieved you are ready to build: ```bash cd $GOPATH/src/github.com/89luca89/pakkero; make ``` or to test ```bash cd $GOPATH/src/github.com/89luca89/pakkero; make test ``` The binary file will be in `$GOPATH/src/github.com/89luca89/pakkero/dist` The following are hard dependencies: ``` - go -> to build the launcher - ls - sed - strip -> to strip the launcher ``` The following are weak dependencies ``` - upx -> needed for launcher compression (optional) ``` **GO 1.13+ needed** **Dependencies are checked at runtime and an error message will specify what is missing** # Disclaimer **This is a for-fun and educational project**, complete protection for a binary is **impossible**, in a way or another there is always someone that will reverse it, even if only based on 0 an 1, so this is more about exploring some arguments that to create an anti-reverse launcher. --- Pakkero is divided in two main pieces, the packer part (Pakkero itself) and the launcher part. ## Part 1: the packer Pakkero can be launched like: ```bash pakkero --file ./target-file -o ./output-file -register-dep dependency-file -c ``` ![demo](pics/demo.png) ### Usage Typing `pakker -h` the following output will be shown: ```bash Usage: pakkero -file /path/to/file -offset OFFSET (-o /path/to/output) (-c) (-register-dep /path/to/file) -file Target file to Pack -o place the output into (default is .enc), optional -c compress the output to occupy less space (uses UPX), optional -offset Offset where to start the payload (Number of Bytes) -enable-stdout Whether to wait and handle the process stdout/sterr or not (false by default, optional) -register-dep /path/to/dependency to analyze and use as fingerprint (absolutea, optional) -v Check pakkero version ``` Below there is a full explanation of provided arguments: * **file**: The file we want to pack * **o**: (optional) The file output that we will create * **c**: (optional) If specified, UPX will be used to further compress the Launcher * **offset**: (optional) The number of bytes from where to start the payload (increases if not using compression) * **enable-stdout** (optional) whether to enable or not the handling of the stdout/err of the payload **disabled by default, less secure** * **regiser-dep** (optional) Path to a file that can be used to register the fingerprint of a dependency to ensure that the Launcher runs only if a file with similar fingerprint is present * **v**: Print version ### Packaging **The main intent is to not alter the payload in any way, this can be very important for types of binary that rely on specific order of instructions or relatively fragile timings.** The target of pakkero is not to touch the "payload". Other packers like UPX works by compressing the sections stored within the Section Table of the executable file, relocating the sections and renaming them. It then alters the entry point where the binary will run. While this is really what defines storically a packer, this in some way or another "touches" the payload so can make it unusable (when it works on strict timing, precise elf sections tricks and so on) #### Building To build the project, you can simply use the `Makefile`; - `make` will compile - `make test` will compile and run a run with a simple binary (echo) **Why not using simply go build?** Go build works fine, but will skip a fundamental step in the building process, **the injection of the launcher stub inside Pakkero source** This way the Pakkero binary has inside the source of the Launcher to be used for each packaging. #### Building using Docker Build Pakkero image: ```sh sudo docker build . -t pakkero ``` Run containerized Pakkero: ```sh sudo docker run -it -v :/ext pakkero --file /ext/ -o /ext/.packed ``` #### Building using Podman Build Pakkero image: ```sh sudo podman build . -t pakkero ``` Run containerized Pakkero: ```sh sudo podman run -it -v :/ext pakkero --file /ext/ -o /ext/.packed ``` #### Payload For this purpose the payload is simply compressed using zlib then encrypted using AES256-GCM During encryption, some basic operations are also performed on the payload: - putting garbage random values before and after the payload to mask it - reverse it and change each byte endianess Encryption password is the hash SHA512 of the compiled launcher itself together with the garbage values added to fill the file till the offset, thus providing some integrity protection and anti-tampering. #### Offset The offset will decide **where in the output file the payload starts**. Put simply, after the launcher is compiled (more on the launcher later), the payload is attached to it. The offset ensures that the payload can be put anywhere after it. All the space after the launcher until the payload is filled with random garbage. ![payload](./pics/decryption.png) Being part of the password itself, greater offset will make stronger the encryption, but enlarge the final output file. Optimal value are **at least** 800000 when compression is enabled and **1900000** when disabled. *If not specified a random one will be chosen upon creation. ### Obfuscation The final thing the packer does is compiling the launcher. To protect some of the fundamental part of it (namely where the offset starts) the launcher is *obfuscated* and heavily stripped down. The technique utilized for obfuscating the function and variables name is based on typo-squatting: ![obfuscation](./pics/obfuscation.png) This is done in a pretty naive way, simply put, in the launcher each function/variable which name has to be obfuscated, needs to start with the suffix **ob**, it will be then put into a secret map, and each occurrence will be replaced in the file with a random string of length 128, composed only of runes that have similar shape, namely: ```go mixedRunes := []rune("0OÓÕÔÒÖŌŎŐƠΘΟ") ``` For pure strings in the launcher, they are detected using regular expressions, finding all the words that are comprised between the three type of ticks supported in go ``` ` ' " ``` All of the strings found this way, are then replaced with a function that performs a simple operation of reconstruction of the original string: ```go func ÓΘŌOÒŐÒŌÓÒOŎΘOΟ0ŐÒÖŎÕΟΘÕÓÕÓŎÓŌÕ0ŎŌΘÕŎÕ() string { ŌÒ0ŎŎŐÓÖÖΘO0ŌŌŌÒŌŌÒƠÔÖΘŐÖΟŎƠƠ00Õ0ÖÕ0ÖŐŐÓΟŌΟ := []string{"Ò0ƠŐÖŐŎΘÖƠÔÖÕÓΘÕÕŌŎŐƠÔΘΘƠ", "ÔÒÕΟƠŐÒŌOƠÖ", "ƠΘŐÒƠΘŌ00ΘΘΟÔŎŎΘŐƠŐΘŎΟÕÖÕÖΟÖΘÒÖ"} var ΟŐÔÒÖÔΘÕÔŎÒÓÖÖÒΘ0ÖÔΟÖŎ0ÔOÓÖƠŌÔÓŌŌ []byte for _, ŌΘƠÔÕÔΘÔOÔOŐΟΘŌΘƠÔÕÔΘÔOÔOŐΟΘ := range ŌÒ0ŎŎŐÓÖÖΘO0ŌŌŌÒŌÕÒÔÕŌŎ00ÔÔÒOƠÓÕÔÒ0ΘƠΘŐ0OOŎÓÒŐ0Õ0ÓOÕÓŐƠŌŎÕÖ0ÕÖÔŌΟΟŌÒÖÒÖOΟOÒ0ÖŐŐÓΟŌΟ { ΟŐÔÒÖÔΘÕÔŎÒÓÖÖÒΘ0ÖÔΟÖŎ0ÔOÓÖƠŌÔÓŌŌ = append(ΟŐÔÒÖÔΘÕÔŎÒÓÖÖÒΘ0ÖÔΟÖŎ0ÔOÓÖƠŌÔÓŌŌ, byte(len([]rune(ŌΘƠÔÕÔΘÔOÔOŐΟΘŌΘƠÔÕÔΘÔOÔOŐΟΘ)))) } return string(ΟŐÔÒÖÔΘÕÔŎÒÓÖÖÒΘ0ÖÔΟÖŎ0ÔOÓÖƠŌÔÓŌŌ) } ``` A slice of string is generated, with each element has a lenght derived from the byte value of the original char of the original string. This way each byte of the original string is computed and calculated as the lenght of the correspondent string, casted to rune slice. The launcher is compiled then using: ```go flags = []string{"build", "-a", "-trimpath", "-gcflags", "-N -l -nolocalimports", "-ldflags", "-s -w -extldflags -static", } exec.Command("go", flags...) ``` File is the **stripped**, using `strip` with the flags: ```bash -sxX --remove-section=.bss --remove-section=.comment --remove-section=.eh_frame --remove-section=.eh_frame_hdr --remove-section=.fini --remove-section=.fini_array --remove-section=.gnu.build.attributes --remove-section=.gnu.hash --remove-section=.gnu.version --remove-section=.gosymtab --remove-section=.got --remove-section=.note.ABI-tag --remove-section=.note.gnu.build-id --remove-section=.note.go.buildid --remove-section=.shstrtab --remove-section=.typelink ``` Additionally, if using *UPX*, their headers are **removed and replaced with randomness**, to ensure simple things like `upx -d` will not work. Additionally a series of extra words are removed from the binary and replaced with random bytes, to make it harder to do static analysis: ``` .gopclntab .go.buildinfo .noptrdata .noptrbss .data .rodata .text .itablink .shstrtab .data .dynamic .dynstr .dynsym .gnu.version_r .gopclntab .got.plt .init_array .interp .itablink .rela.dyn .rela.plt .tbss .plt .init name runtime command cmd ptr process unicode main path get reflect context debug fmt sync sort size heap fatal call fixed slice bit file read write buffer encrypt decrypt hash state external internal float env trace pid ``` Output of readelf to see the effect: ![readelf](./pics/readelf.png) #### File Entropy Using binwalk to analyze the file entropy can give some hint on how the process works: This is the entropy of the binary we want to package (for this example /usr/bin/bash): ![original-entropy.png](./pics/original-entropy.png) This is the entropy of a packaged binary **without compression** ![uncompressed](./pics/uncompressed-entropy.png) This is the entropy of a packaged binary **with compression** ![compressed](./pics/compressed-entropy.png) In both cases (but mainly the first) it is possible to see when the launcher stops and the garbage before the payload starts. This is really not a problem, because the offset of garbage is both pre-poned **and** post-poned to the payload, and the "secret number" of when it starts is kept inside the launcher and computed at runtime. This is obviously vulnerable, reversing the binary will reveal the secret, all the launcher part is dedicated to the implementation of a series of measures to **block dynamic analysis** and try to force static analysis. ## Part 2: the launcher The launcher is the second part of the project, it allows to decompress, decrypt and launch the payload without touching storage, but using a file descriptor in RAM. This is a well known technique as it is possible to read: - [In-Memory-Only ELF Execution (Without tmpfs) Mrs Quis Will Think of a Better Title](https://magisterquis.github.io/2018/03/31/in-memory-only-elf-execution.html) - [ELF in-memory execution](https://blog.fbkcs.ru/en/elf-in-memory-execution/) and in many other places in C programming literature. ``` Put briefly, use syscall to create a memory file descriptor (syscall 319 for amd64), write the plaintext payload here, and execute. The fd will be automatically removed after the execution without leaving trace on the storage. ``` ### Possible weakpoints This approach is vulnerable to 1. "memory dump attack", for example pausing the VM during execution and manually search the ram for all file descriptors until you find the right one 2. "proc dump attack", in linux all the file descriptors are in `/proc` so dumping to another disk the complete folder will in a way or another dump the decrypted payload (if done before the execution finishes), **this is even more accentuated if stdout management is enabled** 3. dynamic analysis, during execution "pausing" the process and spot the right fd 4. reversing the binary to find the "secret" (which in our case is the offset) and from there, reverse the encryption process and reconstruct the plaintext For point 1, it is possible to insert hypervisor detection, sandbox detection etc... it is in my TODO list, but I would leave it optional, in case you genuinely want to run the binary in VMs or Dockers. Point 3 (and by consequence point 4) can be made harder by blocking dynamic analysis detecting debuggers, tracers and so on... Forcing static analysis of the decompiled code is already a big step forward in protecting the binary execution. ### Anti-debug Implemented here are a series of anti-debug techniques that are quite common in C/C++, from the **double-ptrace method** to the **ppid analysis** and breakpoints interception. First line of protection is breakpoints interception, on linux, a breakpoints is equivalent to signal *SIGILL* and *SIGTRAP* so: ```go /* Breakpoint on linux are 0xCC and will be interpreted as a SIGTRAP, we will intercept them. */ func obSigTrap(obInput chan obOS.Signal) { obMySignal := <-obInput switch obMySignal { case obSyscall.SIGILL: obExit() case obSyscall.SIGTRAP: obExit() default: return } } ``` This is pretty basic, so we go ahead and try to block **ptrace**: ```go // attach to PTRACE, register if successful // attach A G A I N , register if unsuccessful // this protects against custom ptrace (always returning 0) // against NOP attacks and LD_PRELOAD attacks func obPtraceDetect() { var obOffset = 0 obProc, _ := obOS.FindProcess(obOS.Getppid()) obErr := obSyscall.PtraceAttach(obProc.Pid) if obErr == nil { obOffset = 5 } obErr = obSyscall.PtraceAttach(obProc.Pid) if obErr != nil { obOffset *= 3 } if obOffset != (3 * 5) { obProc.Signal(obSyscall.SIGCONT) println(1) return } obErr = obSyscall.PtraceDetach(obProc.Pid) if obErr != nil { obProc.Signal(obSyscall.SIGCONT) println(0) return } obProc.Signal(obSyscall.SIGCONT) println(0) } ``` *Double ptraceme* ensures that tampering the ptrace loading with a fake ptrace lib that always returns 0, would result in a failure. CMD Line detection, would check for common processes for debugging, this is pretty naive check: ```go /* Check the process cmdline to spot if a debugger is inline */ func obParentCmdLineDetect() { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/cmdline" obStatParent, _ := obUtilio.ReadFile(obNameFile) if obStrings.Contains(string(obStatParent), "gdb") || obStrings.Contains(string(obStatParent), "dlv") || obStrings.Contains(string(obStatParent), "edb") || obStrings.Contains(string(obStatParent), "frida") || obStrings.Contains(string(obStatParent), "ghidra") || obStrings.Contains(string(obStatParent), "godebug") || obStrings.Contains(string(obStatParent), "ida") || obStrings.Contains(string(obStatParent), "lldb") || obStrings.Contains(string(obStatParent), "ltrace") || obStrings.Contains(string(obStatParent), "strace") || obStrings.Contains(string(obStatParent), "valgrind") { obExit() } } ``` ```go /* Check the process cmdline to spot if a debugger is the PPID of our process */ func obParentDetect() { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/stat" obStatParent, _ := obUtilio.ReadFile(obNameFile) if obStrings.Contains(string(obStatParent), "gdb") || obStrings.Contains(string(obStatParent), "dlv") || obStrings.Contains(string(obStatParent), "edb") || obStrings.Contains(string(obStatParent), "frida") || obStrings.Contains(string(obStatParent), "ghidra") || obStrings.Contains(string(obStatParent), "godebug") || obStrings.Contains(string(obStatParent), "ida") || obStrings.Contains(string(obStatParent), "lldb") || obStrings.Contains(string(obStatParent), "ltrace") || obStrings.Contains(string(obStatParent), "strace") || obStrings.Contains(string(obStatParent), "valgrind") { obExit() } } ``` this goes in conjunction with the TracePid check to see if a parent is tracing us: ```go /* Check the process status to spot if a debugger is active using the TracePid key */ func obParentTracerDetect() { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/status" obStatParent, _ := obUtilio.ReadFile(obNameFile) obStatLines := obStrings.Split(string(obStatParent), "\n") for _, obValue := range obStatLines { if obStrings.Contains(obValue, "TracerPid") { obSplitArray := obStrings.Split(obValue, ":") obSplitValue := obStrings.Replace(obSplitArray[1], "\t", "", -1) if obSplitValue != "0" { obExit() } } } } ``` and verification that the process cmdline corresponds to "argv[0]" (for example, launching `strace mybin arg1` would result in a cmdline of `strace` and argv[0] of `mybin` ```go /* Check the process cmdline to spot if a debugger is launcher "_" and Args[0] should match otherwise */ func obEnvArgsDetect() { obLines, _ := obOS.LookupEnv("_") if obLines != obOS.Args[0] { obExit() } } ``` and check if there is none of the known debuggers inline with the command ```go /* Check the process cmdline to spot if a debugger is inline "_" should not contain the name of any debugger */ func obEnvParentDetect() { obLines, _ := obOS.LookupEnv("_") if obStrings.Contains(obLines, "gdb") || obStrings.Contains(obLines, "dlv") || obStrings.Contains(obLines, "edb") || obStrings.Contains(obLines, "frida") || obStrings.Contains(obLines, "ghidra") || obStrings.Contains(obLines, "godebug") || obStrings.Contains(obLines, "ida") || obStrings.Contains(obLines, "lldb") || obStrings.Contains(obLines, "ltrace") || obStrings.Contains(obLines, "strace") || obStrings.Contains(obLines, "valgrind") { obExit() } } ``` Also a pretty common check to do if we are in a debugger is to see if ENV has the variables LINES and COLUMNS: ```go /* Check the process cmdline to spot if a debugger is active most debuggers (like GDB) will set LINE,COLUMNS or LD_PRELOAD to function, we try to spot this */ func obEnvDetect() { _, obLines := obOS.LookupEnv("LINES") _, obColumns := obOS.LookupEnv("COLUMNS") _, obLineLdPreload := obOS.LookupEnv("LD_PRELOAD") if obLines || obColumns || obLineLdPreload { obExit() } } ``` This can give false positives (example the embedded terminal in VSCode or VIM), but worth checking for a normal environment. Also banally checking for LD_PRELOAD env variable present: ```go /* Check the process is launcher with a LD_PRELOAD set. This can be an injection attack (like on frida) to try and circumvent various restrictions (like ptrace checks) */ func obLdPreloadDetect() { obKey := obStrconv.FormatInt(obTime.Now().UnixNano(), 10) obValue := obStrconv.FormatInt(obTime.Now().UnixNano(), 10) err := obOS.Setenv(obKey, obValue) if err != nil { obExit() } obLineLdPreload, _ := obOS.LookupEnv(obKey) if obLineLdPreload == obValue { err := obOS.Unsetenv(obKey) if err != nil { obExit() } } else { obExit() } } ``` to make it more resilient to "false environment" attacks, we also try and set a random key-value in the environment, and check if it works, to ensure we do not have a "fake" environment (always empty for example). This type of checks are pretty basic and easy to port from C to Go. A couple of checks I would like to port are for example the heap relocation check, as explained in this repo: [debugmenot/test_nearheap.c at master · kirschju/debugmenot · GitHub](https://github.com/kirschju/debugmenot/blob/master/src/test_nearheap.c) > GDB relocates the heap to the end of the bss section This type of check is not easily done in Go because *go does not support pointer arithmetic*, CGO should be the way, but would make it dynamically linked for the C part (or twice the size if statically linked) ### Making difficult to reverse To add to this in many points of the source code it is possible to see that a comment is made: `//OB_CHECK` This is because during the obfuscation phase, every time we encounter this string, we will inject a random permutation of ALL of the anti-debug tricks that will be executed in parallel using go routines. ```go /* GenerateRandomAntiDebug will Insert random order of anti-debug check together with inline compilation to induce big number of instructions in random order */ func GenerateRandomAntiDebug(input string) string { lines := strings.Split(input, "\n") randomChecks := []string{ `obDependencyCheck()`, `obEnvArgsDetect()`, `obParentTracerDetect()`, `obParentCmdLineDetect()`, `obEnvDetect()`, `obEnvParentDetect() `, `obLdPreloadDetect()`, `obParentDetect()`, } // find OB_CHECK and put the checks there. for i, v := range lines { if strings.Contains(v, "// OB_CHECK") { threadString := "" checkString := "" // randomize order of check to replace for j, v := range ShuffleSlice(randomChecks) { threadString = threadString + "go " + v + ";" checkString += v if j != (len(randomChecks) - 1) { checkString += `||` } } // add action in case of failed check lines[i] = threadString } } // back to single string return strings.Join(lines, "\n") } ``` The generated source will be filled with this always-changing code, that will make difficult to use NOP attacks, manual jump using breakpoints and make confusion in the graph view of disassemblers like Cutter, IDA Pro or Ghidra. So the main, for example, becomes something like: ```go func main() { // Prepare to intercept SIGTRAP ÖÖΘÓOŐƠOΟŌΟŐÔÒÕÓÒÒÒOŎŌO0ÔŌÓÖOŐŎΟŌŌŌÔ0OOŌŐΘŎΘÔOOOÓΘŐΘ00ƠŎÖÖ0ÔÕÕŎŎŎÒÖO00ŎÔΘÓOÖ0ΘÔOΟÒŐŐƠÒΘÒ0ŎŌŌÖΟÓ0ƠŎŌŌΟŎΘŐÖÒŐΘÔÕOŌÕŎÒŎÔŌÓƠÓŌŐΟΟÒÒƠ := make(chan ÒÕ0ΟÓŎ0ÖÒŌƠÒΘ0ÓΘΘƠΟÕƠΘÕO0OŐOŎOƠŎƠÖOOÒÖÒO0ÕÕÓÖΘΘÓÒÕŌŐΘŐƠÖOÕΘÔÕÖƠƠŌŐƠ0ÖÖƠŌΟ0ΘƠÕÒÔƠÒOÒΘÔΟÒ0OÕOŌÕΘÒÒŐÓΟÕÖÕŎΟƠŎOŌÔΟŎŐÒŎŎOƠOO0Ō0ŌŐÓÖŎÖ.Signal, 1) ÔƠÕΟÒΘΘÖŎ0ÓŎÒŎOÕΟÒ0ŐΘƠÓOƠOÔÒÕŐ0OÔÒÓΟOÓŐŐŎΟÒŐÒ0ŌΟO0ΟOÔOΘOƠƠÒ0ŐÓΘÖΘΘÕÖΟÔÖÖΘÔŎÕ00ŐÖÔŎŎŌ0ŐƠOÖÖΟΘÕÓŌÖÔÖÕÒƠƠÓÓ0ÒÖƠŌÔÔŐƠŌOŐÔÒ0ŐÕÖOŐŌŎÔÔ.Notify(ÖÖΘÓOŐƠOΟŌΟŐÔÒÕÓÒÒÒOŎŌO0ÔŌÓÖOŐŎΟŌŌŌÔ0OOŌŐΘŎΘÔOOOÓΘŐΘ00ƠŎÖÖ0ÔÕÕŎŎŎÒÖO00ŎÔΘÓOÖ0ΘÔOΟÒŐŐƠÒΘÒ0ŎŌŌÖΟÓ0ƠŎŌŌΟŎΘŐÖÒŐΘÔÕOŌÕŎÒŎÔŌÓƠÓŌŐΟΟÒÒƠ, O0OÓΟ0ŎŐOƠOŎƠ0ÓƠΘÒƠÕƠÖÓÕŎƠŎOΟΘƠŌƠÖÔÓÔÕŐŎŌŐŐƠΘO0Ô0Ò0OÕƠ0ŐÓÖÔ0ŎΘÕÔÔŎƠÓÔOÕO0ÓΘÒOŎŎÔ0ÓƠ0ÖŎŎΘO0ƠŐÖŐŌOOOΟOÒΘΟΟƠΘΟ0ÖÔŎƠÓŌÕÕOΘÕŎŐŌΘOŐΘÕŌ.SIGTRAP, O0OÓΟ0ŎŐOƠOŎƠ0ÓƠΘÒƠÕƠÖÓÕŎƠŎOΟΘƠŌƠÖÔÓÔÕŐŎŌŐŐƠΘO0Ô0Ò0OÕƠ0ŐÓÖÔ0ŎΘÕÔÔŎƠÓÔOÕO0ÓΘÒOŎŎÔ0ÓƠ0ÖŎŎΘO0ƠŐÖŐŌOOOΟOÒΘΟΟƠΘΟ0ÖÔŎƠÓŌÕÕOΘÕŎŐŌΘOŐΘÕŌ.SIGILL) go ÔΘƠƠƠŎÔŐŌÖOŐÒÓO0ÖΘΘ0ΘŐŎΘ0ÖŌOÒŐÕ0ÒŐ0ƠÖÕŐÓÕÕŌƠƠÖÒÔŎÔÔÖÕŐÖΟÒÖŐÓÕÔÓΘΟÕƠOŐ0ŌÓÖÔOƠÓ0ŎÓ0ŎOÒΟÓOΘÔΟÒÔƠΘŐÒΘΘÓƠΟƠÓÒÓƠ0Ŏ0ÓÒŌOŌÕÕΟŌOΘ0ŎƠŎ0ÕƠƠ(ÖÖΘÓOŐƠOΟŌΟŐÔÒÕÓÒÒÒOŎŌO0ÔŌÓÖOŐŎΟŌŌŌÔ0OOŌŐΘŎΘÔOOOÓΘŐΘ00ƠŎÖÖ0ÔÕÕŎŎŎÒÖO00ŎÔΘÓOÖ0ΘÔOΟÒŐŐƠÒΘÒ0ŎŌŌÖΟÓ0ƠŎŌŌΟŎΘŐÖÒŐΘÔÕOŌÕŎÒŎÔŌÓƠÓŌŐΟΟÒÒƠ) // ÔOÒŎ00ƠÒŎΟOÓΟÖΟOÖΘÓƠƠƠŎÖŌŐŐÒÓÔOŎÒÔΘŌΟÓŐÒΟƠOÕÖÕƠƠÕŎÔÔÒΟOÖO0ŐÔÓÓƠÒ0ŎΘOÒŎOŐÔŌƠÓÒÕÕΟO0ÓƠÒŎŌÖOŌÖOÕÒƠŐÓΟŐÔÔŎŐÓÔÓOƠΘOOŎ0ƠΘÓΘÕÔÕƠÓΘÒÔŐΟÒ() go ÔŐŌŌÒÓ0OΟO0ÖΟŌ0ƠÒ0ÒŌÔOΟΟÖŎÕ0ΘÓΘOOΟΟΘ0Ơ0ΘŐÕ0ΟÔŐ0ŐŌÕ00ŌOΟΟÒÕÒÖŌÓOOÒÔΘÒΘÒÔŌŎΟÒŐŌÕÒÕŎÖÒÖÕΘ00OÖÓŌÓÖÖÓÔƠΘŌ0ÓÕ0ŌÖΘOÖ0ÓŐƠ0ΟÖ00ŌŐŐΘΘÕÒƠÕΟ() go ÖƠŎŎΘΟÓÓÒÖÒ0ÓΘŎÖΘŌ0ŎOÕÔÓƠÔÔΘŌÔΘ0OÕOΟOÕƠŌÒŎ0O0ŎΘΟÒÕΟΟÓ0ŎΟÒΘÕΟÖŎÕÔOÕOΘΘŐÖŌŐΟÔΟÖΟ0OÔÓ0ΟŐOŌÕŌOŌOÕÒÒΘΟŎƠΟÒŌ0ƠΟÔOÒÓÒΟŐÕÒŌƠÔÖ0ŐÖÖÖÓΟƠŌÕ() go ƠΘÔŐŎŌÒŌÖŌΟŎOΟŐŎŎΘOƠÔ0ŐƠΘÒΟƠŐŌ0ŌΘΟΟÒŎÖÓ0ÒΟŐ0ƠΘŌÒÔÔŌƠŌÖOƠÓÔŌOÓ0OŐÕÒ0ŌÖÓŎÕŎÕÓÓ0ÒΘÖΟΘŎÕÓƠŐΟÕΟŌÔŎŌÓOÒÓ0Ŏ0ΟÕÔÒŌƠΘŌΟŎŐΘƠÔÓŐΘŎÔŌŌO0ƠÒÖÖ() go ΟƠŐΟÔOƠÔΟΟÓΘÖOŐΟÕƠ0ΘŐÓÖÔŎÒ0OÔŐÓΟƠΘΘΘÔOÖŌÕŎÒŎΟÔÕÒŎÓ0OÖƠ0ÖÓOÒŐÓŐÔΘÓŌƠÕŎÕÒΟÖŌÒŎΟ0ÒÔÔÕ0ÕÓÒÓÒÔ0ŎO0Θ0ΘŐÖΟŎÖŌOΘÒΘ0ÕŐÖÓΟOÖÒÒÔÕOƠÒŎΘO0ÔÓÔ() go ÒŎ0ÖƠÔŌÔÖΟΘƠΟÒƠƠÖ0ŐÓÓΟOÓŎÖΟÔŌOOΟÔÒÓƠÓΟŎŎ0ÕƠŌÕÒÒÖ0OŌÕŐ0ƠÖΟƠÕÔÒÖŎÖÔÕÔŐOƠŌƠÒΘŌŎÖOŎΘÓÔÔΟŐŌΟŐƠÕΟÖŐ0ÔΘƠŌƠƠÒOOŎÔ0ŐΟÕÕŌÕÔÕÒŐÔŐÔÖÓƠÖΟOŌŎƠ() go ÔŌÕŌŐ0ŐÓÖΘŐÖΟŎΟƠŎOÖÖÕÒΘƠŐΟÓΟΘOÒƠΟ0ÒÒÖÖŌŎŌΘƠƠOΟÒƠΟΘOÓÕŌÕÒÕO0ŎOÔŐOÖŎÓÔOO0OÕŌOΘ0ÒƠƠÔŌÔÔÔŐΟ0ΘΘOŌOÒÕÒÕÕOÔÕŐŌΟÒŌÔ00ÖƠÔΟ0ΟÔŐΟƠÖÕΘ0ÖΟŌÖÖ() go ÒŎÒ0ΘŐŐÔƠΘÒŐŎΘÓÕÕÔŎÖ0ŌÖÖΟÖÓÔÓÒÖÖŌŐΘŌ0ÕÖŎÓΟŌŌÒÖ0ΘÖOΘŎŎÖΘΟÓÒƠΟŐOƠOΘΘÓ0ÕΘŐƠÔÖΟΟ0OΘÖΘŎΟŐÕΘŐΟÓÓƠƠŐÒΟÖΘOŌƠΟΘŎ0ÒΟƠƠÔŎ00ŌÕÓÒ0ŌŎÒOƠŎÖŐÕÓƠ() go ŎÓÕƠŌOŌΟÖÓ0ÒÓΘΟ0ƠŎÖΟŌŎÕÒÕÓŎÖÕƠÒŎŐƠÒƠ0ÒƠÖÕŎÒŐÓÔÓÒ0ΟÕŌÒŐOŐŌÖOÕƠƠÔŎÖ0ÒÓÒÕOÖÕƠÔÕOÔÖΟΘÕÔ0OÕƠÓOÓOÔÖÒ0ΟÖOÖÔΘŌOŌŎΘΘΘ0ŐŌOÔÒΟƠ0ŐÓÕŐÔŐΟÒŐÒΟ() ΟƠŐΟÔOƠÔΟΟÓΘÖOŐΟÕƠ0ΘŐÓÖÔŎÒ0OÔŐÓΟƠΘΘΘÔOÖŌÕŎÒŎΟÔÕÒŎÓ0OÖƠ0ÖÓOÒŐÓŐÔΘÓŌƠÕŎÕÒΟÖŌÒŎΟ0ÒÔÔÕ0ÕÓÒÓÒÔ0ŎO0Θ0ΘŐÖΟŎÖŌOΘÒΘ0ÕŐÖÓΟOÖÒÒÔÕOƠÒŎΘO0ÔÓÔ() go ÔŐŌŌÒÓ0OΟO0ÖΟŌ0ƠÒ0ÒŌÔOΟΟÖŎÕ0ΘÓΘOOΟΟΘ0Ơ0ΘŐÕ0ΟÔŐ0ŐŌÕ00ŌOΟΟÒÕÒÖŌÓOOÒÔΘÒΘÒÔŌŎΟÒŐŌÕÒÕŎÖÒÖÕΘ00OÖÓŌÓÖÖÓÔƠΘŌ0ÓÕ0ŌÖΘOÖ0ÓŐƠ0ΟÖ00ŌŐŐΘΘÕÒƠÕΟ() go ƠΘÔŐŎŌÒŌÖŌΟŎOΟŐŎŎΘOƠÔ0ŐƠΘÒΟƠŐŌ0ŌΘΟΟÒŎÖÓ0ÒΟŐ0ƠΘŌÒÔÔŌƠŌÖOƠÓÔŌOÓ0OŐÕÒ0ŌÖÓŎÕŎÕÓÓ0ÒΘÖΟΘŎÕÓƠŐΟÕΟŌÔŎŌÓOÒÓ0Ŏ0ΟÕÔÒŌƠΘŌΟŎŐΘƠÔÓŐΘŎÔŌŌO0ƠÒÖÖ() go ÖƠŎŎΘΟÓÓÒÖÒ0ÓΘŎÖΘŌ0ŎOÕÔÓƠÔÔΘŌÔΘ0OÕOΟOÕƠŌÒŎ0O0ŎΘΟÒÕΟΟÓ0ŎΟÒΘÕΟÖŎÕÔOÕOΘΘŐÖŌŐΟÔΟÖΟ0OÔÓ0ΟŐOŌÕŌOŌOÕÒÒΘΟŎƠΟÒŌ0ƠΟÔOÒÓÒΟŐÕÒŌƠÔÖ0ŐÖÖÖÓΟƠŌÕ() go ÒŎÒ0ΘŐŐÔƠΘÒŐŎΘÓÕÕÔŎÖ0ŌÖÖΟÖÓÔÓÒÖÖŌŐΘŌ0ÕÖŎÓΟŌŌÒÖ0ΘÖOΘŎŎÖΘΟÓÒƠΟŐOƠOΘΘÓ0ÕΘŐƠÔÖΟΟ0OΘÖΘŎΟŐÕΘŐΟÓÓƠƠŐÒΟÖΘOŌƠΟΘŎ0ÒΟƠƠÔŎ00ŌÕÓÒ0ŌŎÒOƠŎÖŐÕÓƠ() go ΟƠŐΟÔOƠÔΟΟÓΘÖOŐΟÕƠ0ΘŐÓÖÔŎÒ0OÔŐÓΟƠΘΘΘÔOÖŌÕŎÒŎΟÔÕÒŎÓ0OÖƠ0ÖÓOÒŐÓŐÔΘÓŌƠÕŎÕÒΟÖŌÒŎΟ0ÒÔÔÕ0ÕÓÒÓÒÔ0ŎO0Θ0ΘŐÖΟŎÖŌOΘÒΘ0ÕŐÖÓΟOÖÒÒÔÕOƠÒŎΘO0ÔÓÔ() go ŎÓÕƠŌOŌΟÖÓ0ÒÓΘΟ0ƠŎÖΟŌŎÕÒÕÓŎÖÕƠÒŎŐƠÒƠ0ÒƠÖÕŎÒŐÓÔÓÒ0ΟÕŌÒŐOŐŌÖOÕƠƠÔŎÖ0ÒÓÒÕOÖÕƠÔÕOÔÖΟΘÕÔ0OÕƠÓOÓOÔÖÒ0ΟÖOÖÔΘŌOŌŎΘΘΘ0ŐŌOÔÒΟƠ0ŐÓÕŐÔŐΟÒŐÒΟ() go ÔŌÕŌŐ0ŐÓÖΘŐÖΟŎΟƠŎOÖÖÕÒΘƠŐΟÓΟΘOÒƠΟ0ÒÒÖÖŌŎŌΘƠƠOΟÒƠΟΘOÓÕŌÕÒÕO0ŎOÔŐOÖŎÓÔOO0OÕŌOΘ0ÒƠƠÔŌÔÔÔŐΟ0ΘΘOŌOÒÕÒÕÕOÔÕŐŌΟÒŌÔ00ÖƠÔΟ0ΟÔŐΟƠÖÕΘ0ÖΟŌÖÖ() go ÒŎ0ÖƠÔŌÔÖΟΘƠΟÒƠƠÖ0ŐÓÓΟOÓŎÖΟÔŌOOΟÔÒÓƠÓΟŎŎ0ÕƠŌÕÒÒÖ0OŌÕŐ0ƠÖΟƠÕÔÒÖŎÖÔÕÔŐOƠŌƠÒΘŌŎÖOŎΘÓÔÔΟŐŌΟŐƠÕΟÖŐ0ÔΘƠŌƠƠÒOOŎÔ0ŐΟÕÕŌÕÔÕÒŐÔŐÔÖÓƠÖΟOŌŎƠ() ÒŎ0ÖƠÔŌÔÖΟΘƠΟÒƠƠÖ0ŐÓÓΟOÓŎÖΟÔŌOOΟÔÒÓƠÓΟŎŎ0ÕƠŌÕÒÒÖ0OŌÕŐ0ƠÖΟƠÕÔÒÖŎÖÔÕÔŐOƠŌƠÒΘŌŎÖOŎΘÓÔÔΟŐŌΟŐƠÕΟÖŐ0ÔΘƠŌƠƠÒOOŎÔ0ŐΟÕÕŌÕÔÕÒŐÔŐÔÖÓƠÖΟOŌŎƠ() go ÒŎ0ÖƠÔŌÔÖΟΘƠΟÒƠƠÖ0ŐÓÓΟOÓŎÖΟÔŌOOΟÔÒÓƠÓΟŎŎ0ÕƠŌÕÒÒÖ0OŌÕŐ0ƠÖΟƠÕÔÒÖŎÖÔÕÔŐOƠŌƠÒΘŌŎÖOŎΘÓÔÔΟŐŌΟŐƠÕΟÖŐ0ÔΘƠŌƠƠÒOOŎÔ0ŐΟÕÕŌÕÔÕÒŐÔŐÔÖÓƠÖΟOŌŎƠ() go ÔŌÕŌŐ0ŐÓÖΘŐÖΟŎΟƠŎOÖÖÕÒΘƠŐΟÓΟΘOÒƠΟ0ÒÒÖÖŌŎŌΘƠƠOΟÒƠΟΘOÓÕŌÕÒÕO0ŎOÔŐOÖŎÓÔOO0OÕŌOΘ0ÒƠƠÔŌÔÔÔŐΟ0ΘΘOŌOÒÕÒÕÕOÔÕŐŌΟÒŌÔ00ÖƠÔΟ0ΟÔŐΟƠÖÕΘ0ÖΟŌÖÖ() go ƠΘÔŐŎŌÒŌÖŌΟŎOΟŐŎŎΘOƠÔ0ŐƠΘÒΟƠŐŌ0ŌΘΟΟÒŎÖÓ0ÒΟŐ0ƠΘŌÒÔÔŌƠŌÖOƠÓÔŌOÓ0OŐÕÒ0ŌÖÓŎÕŎÕÓÓ0ÒΘÖΟΘŎÕÓƠŐΟÕΟŌÔŎŌÓOÒÓ0Ŏ0ΟÕÔÒŌƠΘŌΟŎŐΘƠÔÓŐΘŎÔŌŌO0ƠÒÖÖ() go ÒŎÒ0ΘŐŐÔƠΘÒŐŎΘÓÕÕÔŎÖ0ŌÖÖΟÖÓÔÓÒÖÖŌŐΘŌ0ÕÖŎÓΟŌŌÒÖ0ΘÖOΘŎŎÖΘΟÓÒƠΟŐOƠOΘΘÓ0ÕΘŐƠÔÖΟΟ0OΘÖΘŎΟŐÕΘŐΟÓÓƠƠŐÒΟÖΘOŌƠΟΘŎ0ÒΟƠƠÔŎ00ŌÕÓÒ0ŌŎÒOƠŎÖŐÕÓƠ() go ΟƠŐΟÔOƠÔΟΟÓΘÖOŐΟÕƠ0ΘŐÓÖÔŎÒ0OÔŐÓΟƠΘΘΘÔOÖŌÕŎÒŎΟÔÕÒŎÓ0OÖƠ0ÖÓOÒŐÓŐÔΘÓŌƠÕŎÕÒΟÖŌÒŎΟ0ÒÔÔÕ0ÕÓÒÓÒÔ0ŎO0Θ0ΘŐÖΟŎÖŌOΘÒΘ0ÕŐÖÓΟOÖÒÒÔÕOƠÒŎΘO0ÔÓÔ() go ÔŐŌŌÒÓ0OΟO0ÖΟŌ0ƠÒ0ÒŌÔOΟΟÖŎÕ0ΘÓΘOOΟΟΘ0Ơ0ΘŐÕ0ΟÔŐ0ŐŌÕ00ŌOΟΟÒÕÒÖŌÓOOÒÔΘÒΘÒÔŌŎΟÒŐŌÕÒÕŎÖÒÖÕΘ00OÖÓŌÓÖÖÓÔƠΘŌ0ÓÕ0ŌÖΘOÖ0ÓŐƠ0ΟÖ00ŌŐŐΘΘÕÒƠÕΟ() go ŎÓÕƠŌOŌΟÖÓ0ÒÓΘΟ0ƠŎÖΟŌŎÕÒÕÓŎÖÕƠÒŎŐƠÒƠ0ÒƠÖÕŎÒŐÓÔÓÒ0ΟÕŌÒŐOŐŌÖOÕƠƠÔŎÖ0ÒÓÒÕOÖÕƠÔÕOÔÖΟΘÕÔ0OÕƠÓOÓOÔÖÒ0ΟÖOÖÔΘŌOŌŎΘΘΘ0ŐŌOÔÒΟƠ0ŐÓÕŐÔŐΟÒŐÒΟ() go ÖƠŎŎΘΟÓÓÒÖÒ0ÓΘŎÖΘŌ0ŎOÕÔÓƠÔÔΘŌÔΘ0OÕOΟOÕƠŌÒŎ0O0ŎΘΟÒÕΟΟÓ0ŎΟÒΘÕΟÖŎÕÔOÕOΘΘŐÖŌŐΟÔΟÖΟ0OÔÓ0ΟŐOŌÕŌOŌOÕÒÒΘΟŎƠΟÒŌ0ƠΟÔOÒÓÒΟŐÕÒŌƠÔÖ0ŐÖÖÖÓΟƠŌÕ() ..... ``` ### ### Dependency Registration Another form of protection, is the *dependency registration*. The idea behind it is to protect not only elf binaries, but also executable scripts, like python, bash, perl, php or anything with a shebang. A common attack that is possible is a "man in the middle execution", for example, let the payload be a bash script, in the moment of execution `/usr/bin/env bash` is called to execute the content of the script. If in the environment (or really with a symlink on /usr/bin/bash) we put something like: ```bash #!/bin/sh cp $0 /tmp/plaintext /usr/bin/real-bash $@ ``` This will result in a transparent execution but a dumped plaintext in /tmp (credits for the attack idea to [mrnfrancesco (Francesco Marano) · GitHub](https://github.com/mrnfrancesco) ) ### So what can we do to ensure nothing like this happens? We will *register a binary/dependency* that is necessary for the payload to run (for example /usr/bin/bash for a bash script, /usr/bin/python3 for a python script etc etc) and verify that the dependency in the target where we would execute the payload is valid or not. Now there is a problem, how do we verify that it's a valid binary? Using an Hash is too strict , for example /usr/bin/bash on fedora is different from the one on centos 8, but both are valid binaries. Only the presence of it is not enough (like in the example attack before) Some basic checks are made: - the file exists - file size is +/- 15% of the registered one But something more is needed. #### Byte Frequency Distribution Study To address the problem it is possible to recycle a technique mostly used in the data-recovery territory: the byte frequency distribution study. References: - [byte frequency analysis descriptor with spatial information for file fragment classification| Semantic Scholar](https://www.semanticscholar.org/paper/BYTE-FREQUENCY-ANALYSIS-DESCRIPTOR-WITH-SPATIAL-FOR-Xie-Abdullah/c39872eae0c61ecf47603aab3f5c1545ee612ac9) - [A New Approach to Content-based File Type Detection](https://arxiv.org/pdf/1002.3174) The idea is to register the BFD of our dependency, then calculate the correlation index of Bravais-Pearson to see if the two dataset are linearly correlated. > Ref: [Pearson correlation coefficient - Wikipedia](https://en.wikipedia.org/wiki/Pearson_correlation_coefficient) Pearson's correlation coefficient is the [covariance](https://en.wikipedia.org/wiki/Covariance "Covariance") of the two variables divided by the product of their [standard deviations](https://en.wikipedia.org/wiki/Standard_deviations "Standard deviations"). ![pearson](https://wikimedia.org/api/rest_v1/media/math/render/svg/f76ccfa7c2ed7f5b085115086107bbe25d329cec) If the index indicates strong correlation, we know that the two file are of the same type (binary) A second step is to study the combined standard deviation of the two datasets (std deviation of the first and the second) and see if both values, the correlation and the combined std deviation are in certain ranges. This ensures that the dependency we are finding is of *the same type* (a binary) using the Bravais-Pearson index and *similar distribution* from the combined std deviation. Here an example of a valid dependency: /usr/bin/bash on fedora30 vs centos7 ![bfd](./pics/bfd-std.png) Blue and green the two BFD of the binaries, in green the combined std deviation. This method is able to distinguish (and stop) the use of different (but functionally equal) binaries like zsh, dash or busybox ### Decryption The last line of defense is also the encryption of the payload. The decryption key of the payload is the sha512sum of the compiled launcher itself with the random garbage appended to it. For example: With offset 930000 ``` Compiled launcher (800kb) OFFSET1 (130kb) Payload OFFSET2 ( different one, 130kb) ``` The decryption key is `sha512sum(Launcher+OFFSET1)` This protects from file-based NOP attacks to remove some instructions from the launcher, and acts also as binary validation. ![payload](./pics/decryption.png) The payload is structured as above, OFFSET1 **ends on the offset value**, OFFSET2 is calculated as the byte reverse of the offset value. The procedure will: - calculate the offset - take the launcher+OFFSET1, sha512sum it - remove OFFSET2 random bytes at the end - decrypt payload using the calculated sha512sum So **THE REAL DECRYPTION KEY IS BASED ON THE OFFSET ITSELF**, all the obfuscation/anti-debug is to protect this information that is stored in an obfuscated string (that is not saved but computed at runtime) of random name and content. ### Execution As explained above, we will use a memory file descriptor to execute the binary without passing for the storage. The binary will be executed using the `Command` library of Go, that uses the syscall exec under the hood, so no new shells are instantiated. ### **If stdout management is NOT enabled (default)** The process is launched and disowned. Upon the termination of the launcher process, the `/proc/PID/fd/mem` of the process is deleted, so the only "copy" of the payload is in the process table of the detached process itself **This is the most secure approach** as it deletes all instances of the plaintext payload, leaving it only in a highly private part of the RAM of the process itself, even gaining immunity to /proc dump attacks This way even a script launcher with this approach is not possible to be retrieved: ![stdout](./pics/handle-stdout.png) ### **If stdout management is enabled** Two routines are used to pipe the payload stderr and stdout to the launcher process. Also piping is supported. For IO heavy processes it is possible to insert in the `Scan` of the outputs an `OB_CHECK` like this: ```go // OB_CHECK // async fetch stdout go func() { defer obWaitGroup.Done() for obStdoutScan.Scan() { // OB_CHECK println(obStdoutScan.Text()) } }() // OB_CHECK // async fetch stderr go func() { defer obWaitGroup.Done() for obStderrScan.Scan() { // OB_CHECK println(obStderrScan.Text()) } }() ``` This will make an impact on performance (all check are executed **for each IO on any standard output/error**) but can give a layer of hardness to process hijacking or tracing ***this is the least secure approach*** as while the launcher is running the `/proc/PID/fd/mem` of the process is still accessible and thus containing the plaintext payload ready to be stealed This is particularly discouraged for **srcipts payloads**, as they are even easier to spot as the path is directly in the process ![handle](./pics/handle-stdout-2.png) With binaries the approach is safer (only the binary name is in the process, thus making it hard to spot requiring a complete /proc dump) ## License [![FOSSA Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2F89luca89%2Fpakkero.svg?type=large)](https://app.fossa.com/projects/git%2Bgithub.com%2F89luca89%2Fpakkero?ref=badge_large) ================================================ FILE: data/launcher.go ================================================ // Package main. package main import ( obBufio "bufio" obBytes "bytes" obZlib "compress/zlib" obAES "crypto/aes" obCipher "crypto/cipher" obSHA "crypto/sha512" obBase64 "encoding/base64" obBinary "encoding/binary" obErrors "errors" obUtilio "io/ioutil" obMath "math" obOS "os" obExec "os/exec" obSignal "os/signal" obStrconv "strconv" obStrings "strings" obSync "sync" obSyscall "syscall" obTime "time" obUnsafe "unsafe" ) type obDependency struct { obDepSize string obDepName string obDepBFD []float64 } // Stdout variable will be overwritten during compilation. var Stdout string = "ENABLESTDOUT" const ( obErr = 1 obCorrelationLevel = 0.4 obStdLevel = 1 obFileSizeLevel = 15 ) func obExit() { println("https://shorturl.at/crzEZ") obOS.Exit(obErr) } // Breakpoint on linux are 0xCC and will be interpreted as a // SIGTRAP, we will intercept them. func obSigTrap(obInput chan obOS.Signal) { obMySignal := <-obInput switch obMySignal { case obSyscall.SIGILL: obExit() case obSyscall.SIGTRAP: obExit() default: return } } // attach to PTRACE, register if successful // attach A G A I N , register if unsuccessful // this protects against custom ptrace (always returning 0) // against NOP attacks and LD_PRELOAD attacks. // // keep attached to avoid late attaching. func obPtraceDetect(pid int, father bool) { obOffset := 0 obProc, _ := obOS.FindProcess(pid) obErr := obSyscall.PtraceAttach(obProc.Pid) if obErr == nil { obOffset = 5 } // continuously check for ptrace on passed pid for { obErr = obSyscall.PtraceAttach(obProc.Pid) if obErr != nil { obOffset *= 3 } obErr = obProc.Signal(obSyscall.SIGCONT) if obErr != nil { // we cannot send sigcont to out pid // we should exit. if father { obExit() } else { obErr = obProc.Signal(obSyscall.SIGTRAP) if obErr != nil { obExit() } } } if obOffset != (3 * 5) { if father { obExit() } else { obErr = obProc.Signal(obSyscall.SIGTRAP) if obErr != nil { obExit() } } } obTime.Sleep(250 * obTime.Millisecond) obOffset /= 3 } } // Check the process cmdline to spot if a debugger is inline. func obParentCmdLineDetect() { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/cmdline" obStatParent, _ := obUtilio.ReadFile(obNameFile) if obStrings.Contains(string(obStatParent), "gdb") || obStrings.Contains(string(obStatParent), "dlv") || obStrings.Contains(string(obStatParent), "edb") || obStrings.Contains(string(obStatParent), "frida") || obStrings.Contains(string(obStatParent), "ghidra") || obStrings.Contains(string(obStatParent), "godebug") || obStrings.Contains(string(obStatParent), "ida") || obStrings.Contains(string(obStatParent), "lldb") || obStrings.Contains(string(obStatParent), "ltrace") || obStrings.Contains(string(obStatParent), "strace") || obStrings.Contains(string(obStatParent), "valgrind") { obExit() } } // Check the process status to spot if a debugger is active using the TracePid key. func obParentTracerDetect() { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/status" obStatParent, _ := obUtilio.ReadFile(obNameFile) obStatLines := obStrings.Split(string(obStatParent), "\n") for _, obValue := range obStatLines { if obStrings.Contains(obValue, "TracerPid") { obSplitArray := obStrings.Split(obValue, ":") obSplitValue := obStrings.Replace(obSplitArray[1], "\t", "", -1) if obSplitValue != "0" { obExit() } } } } // Check the process cmdline to spot if a debugger is the PPID of our process. func obParentDetect() { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/stat" obStatParent, _ := obUtilio.ReadFile(obNameFile) if obStrings.Contains(string(obStatParent), "gdb") || obStrings.Contains(string(obStatParent), "dlv") || obStrings.Contains(string(obStatParent), "edb") || obStrings.Contains(string(obStatParent), "frida") || obStrings.Contains(string(obStatParent), "ghidra") || obStrings.Contains(string(obStatParent), "godebug") || obStrings.Contains(string(obStatParent), "ida") || obStrings.Contains(string(obStatParent), "lldb") || obStrings.Contains(string(obStatParent), "ltrace") || obStrings.Contains(string(obStatParent), "strace") || obStrings.Contains(string(obStatParent), "valgrind") { obExit() } } // Check the process cmdline to spot if a debugger is launcher // "_" and Args[0] should match otherwise. func obEnvArgsDetect() { obLines, _ := obOS.LookupEnv("_") if obLines != obOS.Args[0] { obExit() } } // Check the process cmdline to spot if a debugger is inline // "_" should not contain the name of any debugger. func obEnvParentDetect() { obLines, _ := obOS.LookupEnv("_") if obStrings.Contains(obLines, "gdb") || obStrings.Contains(obLines, "dlv") || obStrings.Contains(obLines, "edb") || obStrings.Contains(obLines, "frida") || obStrings.Contains(obLines, "ghidra") || obStrings.Contains(obLines, "godebug") || obStrings.Contains(obLines, "ida") || obStrings.Contains(obLines, "lldb") || obStrings.Contains(obLines, "ltrace") || obStrings.Contains(obLines, "strace") || obStrings.Contains(obLines, "valgrind") { obExit() } } // Check the process cmdline to spot if a debugger is active // most debuggers (like GDB) will set LINE,COLUMNS or LD_PRELOAD // to function, we try to spot this. func obEnvDetect() { _, obLines := obOS.LookupEnv("LINES") _, obColumns := obOS.LookupEnv("COLUMNS") _, obLineLdPreload := obOS.LookupEnv("LD_PRELOAD") if obLines || obColumns || obLineLdPreload { obExit() } } // Check the process is launcher with a LD_PRELOAD set. // This can be an injection attack (like on frida) to try and circumvent // various restrictions (like ptrace checks). func obLdPreloadDetect() { obKey := obStrconv.FormatInt(obTime.Now().UnixNano(), 10) obValue := obStrconv.FormatInt(obTime.Now().UnixNano(), 10) obErr := obOS.Setenv(obKey, obValue) if obErr != nil { obExit() } obLineLdPreload, _ := obOS.LookupEnv(obKey) if obLineLdPreload == obValue { obErr := obOS.Unsetenv(obKey) if obErr != nil { obExit() } } else { obExit() } } // calculate BFD (byte frequency distribution) for the input dependency. func obUtilBFDCalc(obInput string) []float64 { obFile, _ := obUtilio.ReadFile(obInput) obBfd := make([]float64, 256) for _, obValue := range obFile { obBfd[obValue]++ } return obBfd } // Abs returns the absolute value of obInput. func obUtilAbsCalc(obInput float64) float64 { if obInput < 0 { return -obInput } return obInput } // calculate the covariance of two input slices. func obUtilCovarianceCalc(obDepInput []float64, obTargetInput []float64) float64 { obMeanDepInput := 0.0 obMeanTargetInput := 0.0 for obIndex := 0; obIndex < 256; obIndex++ { obMeanDepInput += obDepInput[obIndex] obMeanTargetInput += obTargetInput[obIndex] } obMeanDepInput /= 256 obMeanTargetInput /= 256 obCovariance := 0.0 for obIndex := 0; obIndex < 256; obIndex++ { obCovariance += (obDepInput[obIndex] - obMeanDepInput) * (obTargetInput[obIndex] - obMeanTargetInput) } obCovariance /= 255 return obCovariance } // calculate the standard deviation of the values in a slice. func obUtilStandardDeviationCalc(obInput []float64) float64 { obSums := 0.0 // calculate the array of rations between the values for obIndex := 0; obIndex < 256; obIndex++ { // increase obInstanceDep to calculate mean value of registered distribution obSums += obInput[obIndex] } // calculate the mean obMeanSums := obSums / float64(len(obInput)) obStdDev := 0.0 // calculate the standard deviation for obIndex := 0; obIndex < 256; obIndex++ { obStdDev += obMath.Pow(obInput[obIndex]-obMeanSums, 2) } obStdDev = (obMath.Sqrt(obStdDev / float64(len(obInput)))) return obStdDev } // calculate the standard deviation of the values of reference over // retrieved values. func obUtilCombinedStandardDeviationCalc(obDepBFD []float64, obTargetBFD []float64) float64 { obDiffs := [256]float64{} obSums := 0.0 obDepSums := 0.0 // calculate the array of rations between the values for obIndex := 0; obIndex < 256; obIndex++ { // add 1 to both to work aroung division by zero obDiffs[obIndex] = obUtilAbsCalc(obDepBFD[obIndex] - obTargetBFD[obIndex]) obSums += obDiffs[obIndex] // increase obInstanceDep to calculate mean value of registered distribution obDepSums += obDepBFD[obIndex] } // calculate the mean obDepSums /= float64(len(obDepBFD)) // calculate the mean obMeanSums := obSums / float64(len(obDepBFD)) obStdDev := 0.0 // calculate the standard deviation for obIndex := 0; obIndex < 256; obIndex++ { obStdDev += obMath.Pow(obDiffs[obIndex]-obMeanSums, 2) } obStdDev = (obMath.Sqrt(obStdDev / float64(len(obDepBFD)))) / obDepSums return obStdDev } func obDependencyCheck() { obStrControl1 := "_DEP" obStrControl2 := "_NAME" obStrControl3 := "_SIZE" obInstanceDep := obDependency{ obDepName: "DEPNAME1", obDepSize: "DEPSIZE2", obDepBFD: []float64{1, 2, 3, 4}, } // control that we effectively want to control the dependencies if (obInstanceDep.obDepName != obStrControl1[1:]+obStrControl2[1:]+"1") && (obInstanceDep.obDepSize != obStrControl1[1:]+obStrControl3[1:]+"2") { // check if the file is a symbolic link obLTargetStats, _ := obOS.Lstat(obInstanceDep.obDepName) if (obLTargetStats.Mode() & obOS.ModeSymlink) != 0 { obExit() } // open dependency in current environment and check it's size obFile, obErr := obOS.Open(obInstanceDep.obDepName) if obErr != nil { obExit() } defer obFile.Close() obStatsFile, _ := obFile.Stat() obTargetDepSize, _ := obStrconv.ParseInt(obInstanceDep.obDepSize, 10, 64) obTargetTreshold := (obTargetDepSize / 100) * obFileSizeLevel // first check if file size is +/- 15% of registered size if (obStatsFile.Size()-obTargetDepSize) < (-1*(obTargetTreshold)) || (obStatsFile.Size()-obTargetDepSize) > obTargetTreshold { obExit() } // Calculate BFD (byte frequency distribution) of target file // and calculate standard deviation from registered fingerprint. obTargetBFD := obUtilBFDCalc(obInstanceDep.obDepName) // Calculate covariance of the 2 dataset obCovariance := obUtilCovarianceCalc(obInstanceDep.obDepBFD, obTargetBFD) // calculate the correlation index of Bravais-Pearson to see if the // two dataset are linearly correlated obDepStdDev := obUtilStandardDeviationCalc(obInstanceDep.obDepBFD) obTargetStdDev := obUtilStandardDeviationCalc(obTargetBFD) obCorrelation := obCovariance / (obDepStdDev * obTargetStdDev) if obCorrelation < obCorrelationLevel { // not correlated, different nature obExit() } obCombinedStdDev := obUtilCombinedStandardDeviationCalc( obInstanceDep.obDepBFD, obTargetBFD) // standard deviation should not be greater than 1 if obCombinedStdDev > obStdLevel { obExit() } } } // Reverse a slice of bytes. func obReverseByteArray(obInput []byte) []byte { obResult := []byte{} for i := range obInput { n := obInput[len(obInput)-1-i] obResult = append(obResult, n) } return obResult } // Change byte endianess. func obByteReverse(obBar byte) byte { var obFoo byte for obStart := 0; obStart < 8; obStart++ { obFoo <<= 1 obFoo |= obBar & 1 obBar >>= 1 } return obFoo } const ( obCloexec uint = 1 // allow seal operations to be performed. obAllowSealing uint = 2 // memfd is now immutable. obSealAll = 0x0001 | 0x0002 | 0x0004 | 0x0008 // amd64 specific. obSysFCNTL = obSyscall.SYS_FCNTL obSysMEMFDCreate = 319 ) func obGetFDPath(obPid int, obFD int, obPayload []byte) string { // check if we are pakkering a script, if it's a script // use specific pid path. if string(obPayload[0:2]) == "#!" { return "/proc/" + obStrconv.Itoa(obPid) + "/fd/" + obStrconv.Itoa(obFD) } // else use self for elf files return "/proc/self/fd/" + obStrconv.Itoa(obFD) } func obLauncher() { // OB_CHECK obNameFile, _ := obOS.Executable() obFile, _ := obOS.Open(obNameFile) defer obFile.Close() // OB_CHECK obOffset, _ := obStrconv.ParseInt("9999999", 10, 64) obStatsFile, _ := obFile.Stat() // calculate final padding obArrayFinalPadding := make([]byte, obBinary.MaxVarintLen64) obByteFinalPadding := obArrayFinalPadding[:obBinary.PutVarint(obArrayFinalPadding, obOffset)] for obIndex := range obByteFinalPadding { obByteFinalPadding[obIndex] = obByteReverse(obByteFinalPadding[obIndex]) } obFinalPadding, _ := obBinary.Varint(obByteFinalPadding) // make it positive! if obFinalPadding < 0 { obFinalPadding *= -1 } // read the complete executable obKey := make([]byte, obOffset) _, obErr := obFile.Read(obKey) if obErr != nil { obExit() } // OB_CHECK obSizeFile := obStatsFile.Size() - obOffset // OB_CHECK _, obErr = obFile.Seek(obOffset, 0) if obErr != nil { obExit() } obCiphertext := make([]byte, obSizeFile) // OB_CHECK _, obErr = obFile.Read(obCiphertext) if obErr != nil { obExit() } obCiphertext = obCiphertext[:int64(len(obCiphertext))-obFinalPadding] // OB_CHECK // the payload was reversed! obCiphertext = obReverseByteArray(obCiphertext) // OB_CHECK // restore endianess for obIndex := range obCiphertext { obCiphertext[obIndex] = obByteReverse(obCiphertext[obIndex]) } // OB_CHECK // the aes-256 psk is the sha512_256 sum of the whole executable // this is also useful to protect against NOP attacks to the anti-debug // features in the binary. // This doubles also as anti-tamper measure. obPassword := obSHA.Sum512_256(obKey) // OB_CHECK obCipherBlock, _ := obAES.NewCipher(obPassword[:]) // OB_CHECK obGCM, _ := obCipher.NewGCM(obCipherBlock) // OB_CHECK obSizeNonce := obGCM.NonceSize() // OB_CHECK // decrypt!!! obNonce, obCiphertext := obCiphertext[:obSizeNonce], obCiphertext[obSizeNonce:] obCompressedPlaintext, _ := obGCM.Open(nil, obNonce, obCiphertext, nil) // OB_CHECK // the payload was compressed! obBufferPlaintext := obBytes.NewReader(obCompressedPlaintext) // OB_CHECK obZlibReader, obErr := obZlib.NewReader(obBufferPlaintext) if obErr != nil { obExit() } // OB_CHECK obPlaintext, _ := obUtilio.ReadAll(obZlibReader) obZlibReader.Close() // OB_CHECK // payload was in b64 obPayload, _ := obBase64.StdEncoding.DecodeString(string(obPlaintext)) // OB_CHECK obFDName := "" obFileDescriptor, _, _ := obSyscall.Syscall(obSysMEMFDCreate, uintptr(obUnsafe.Pointer(&obFDName)), uintptr(obCloexec|obAllowSealing), 0) // OB_CHECK // write payload to FD _, obErr = obSyscall.Write(int(obFileDescriptor), obPayload) if obErr != nil { obExit() } // OB_CHECK // make it immutable _, _, obErr = obSyscall.Syscall(obSysFCNTL, obFileDescriptor, uintptr(1024+9), uintptr(obSealAll)) if !obErrors.Is(obErr, obSyscall.Errno(0)) { obExit() } // OB_CHECK obFDPath := obGetFDPath(obOS.Getpid(), int(obFileDescriptor), obPayload) // OB_CHECK obCommand := obExec.Command(obFDPath) // OB_CHECK obCommand.Args = obOS.Args obCommand.Stdin = obOS.Stdin // OB_CHECK obStdoutIn, _ := obCommand.StdoutPipe() defer obStdoutIn.Close() obStderrIn, _ := obCommand.StderrPipe() defer obStderrIn.Close() obStdout, obErr := obStrconv.ParseBool(Stdout) if obErr != nil { obExit() } if obStdout { // OB_CHECK // launch and remain attached obErr = obCommand.Start() if obErr != nil { obExit() } var obWaitGroup obSync.WaitGroup obWaitGroup.Add(2) obStdoutScan := obBufio.NewScanner(obStdoutIn) obStderrScan := obBufio.NewScanner(obStderrIn) // OB_CHECK // async fetch stdout go func() { defer obWaitGroup.Done() for obStdoutScan.Scan() { println(obStdoutScan.Text()) } }() // OB_CHECK // async fetch stderr go func() { defer obWaitGroup.Done() for obStderrScan.Scan() { println(obStderrScan.Text()) } }() // OB_CHECK obWaitGroup.Wait() } else { // launch and forget obCommand.SysProcAttr = &obSyscall.SysProcAttr{Setpgid: true, Noctty: true} // OB_CHECK obErr = obCommand.Start() if obErr != nil { obExit() } obTime.Sleep(2 * obTime.Second) } } // obIsForked returns wether we are a forked process of ourself, or a new spawn. func obIsForked() bool { obPidParent := obOS.Getppid() obNameFile := "/proc/" + obStrconv.FormatInt(int64(obPidParent), 10) + "/cmdline" obStatParent, _ := obUtilio.ReadFile(obNameFile) return obStrings.Contains(string(obStatParent), obOS.Args[0]) } func main() { // Prepare to intercept SIGTRAP obChannel := make(chan obOS.Signal, 1) obSignal.Notify(obChannel, obSyscall.SIGTRAP, obSyscall.SIGILL) go obSigTrap(obChannel) // OB_CHECK obDependencyCheck() // OB_CHECK obEnvArgsDetect() // OB_CHECK obParentTracerDetect() // OB_CHECK obParentCmdLineDetect() // OB_CHECK obEnvDetect() // OB_CHECK obEnvParentDetect() // OB_CHECK obLdPreloadDetect() // OB_CHECK obParentDetect() // check if we are a forked process, if not, fork // and ptrace ourself, else exit gracefully and continue // with normal execution. // // this workaround is because go does not support traditional fork() // and calling ptrace in the main thread of execution will neuter // any possibility of calling "exec" afterwards. if obIsForked() { // we are a child process, let's ptrace obPtraceDetect(obOS.Getppid(), false) } else { // simulate for self, launch ourself in another // process to ptrace ourself obCommand := obExec.Command(obOS.Args[0], obOS.Args[1:]...) obErr := obCommand.Start() if obErr != nil { println(obErr.Error()) obExit() } go obPtraceDetect(obCommand.Process.Pid, true) // Ok we are set to go! Let's execute the payload // OB_CHECK obLauncher() } } ================================================ FILE: go.mod ================================================ module github.com/89luca89/pakkero go 1.16 require github.com/alegrey91/go-upx v0.2.0 // indirect ================================================ FILE: go.sum ================================================ github.com/alegrey91/go-upx v0.2.0 h1:EFhbmAbFET2mqHRLunHFOVo3+mxdnR2/EQMfv0OOR0k= github.com/alegrey91/go-upx v0.2.0/go.mod h1:qrYpv/uZT6Qs1mrNz3wxrL/u7kbbTWkbVJnHyzsiJmU= ================================================ FILE: internal/pakkero/encryption.go ================================================ /* Package pakkero will pack, compress and encrypt any type of executable. Encryption library */ package pakkero import ( "crypto/aes" "crypto/cipher" "crypto/rand" "crypto/sha512" "fmt" "io" "io/ioutil" ) /* EncryptAESReversed Wrapper around AESGCM encryption this will not only encrypt the payload but: - generate a password using the randomized UPX Binary's sha512_256 sum - cipher the payload with AESGCM using the generated password - swap endianess on all the encrypted bytes - reverse the complete payload. */ func EncryptAESReversed(plaintext []byte, outfile string) (string, error) { // generate a password using the randomized UPX Binary's sha512_256 sum /* the aes-256 psk is the sha512_256 sum of the whole executable this is also useful to protect against NOP attacks to the anti-debug features in the binary. This doubles also as anti-tamper measure. */ b, err := ioutil.ReadFile(outfile) if err != nil { return "", fmt.Errorf("failed to read input file: %w", err) } // use SHA512 (32byte) of the passphrase as key key := sha512.Sum512_256(b) // generate new cipher c, err := aes.NewCipher(key[:]) if err != nil { println(err) } gcm, err := cipher.NewGCM(c) if err != nil { println(err) } nonce := make([]byte, gcm.NonceSize()) if _, err = io.ReadFull(rand.Reader, nonce); err != nil { println(err) } // cipher the payload with AESGCM using the generated password bCiphertext := gcm.Seal(nonce, nonce, plaintext, nil) // swap endianess on all the encrypted bytes for i := range bCiphertext { bCiphertext[i] = ReverseByte(bCiphertext[i]) } ciphertext := string(bCiphertext) // reverse the complete payload ciphertext = string(ReverseByteArray([]byte(ciphertext))) return ciphertext, nil } ================================================ FILE: internal/pakkero/obfuscation.go ================================================ /* Package pakkero will pack, compress and encrypt any type of executable. Obfuscation library */ package pakkero import ( "crypto/rand" "encoding/hex" "fmt" "io/ioutil" "regexp" "strings" ) // Secrets are the group of strings that we want to obfuscate. var Secrets = map[string][]string{} // LauncherStub Stub of the Launcher.go, put here during compilation time. var LauncherStub = "unset" var extras = []string{ // ELF Headers ".gopclntab", ".go.buildinfo", ".noptrdata", ".noptrbss", ".data", ".rodata", ".text", ".itablink", ".shstrtab", ".data", ".dynamic", ".dynstr", ".dynsym", ".gnu.version_r", ".gopclntab", ".got.plt", ".init_array", ".interp", ".itablink", ".rela.dyn", ".rela.plt", ".tbss", ".plt", ".init", // internal golang "name", "runtime", "command", "cmd", "ptr", "process", "unicode", "main", "path", "get", "reflect", "context", "debug", "fmt", "sync", "sort", "size", "heap", "fatal", "call", "fixed", "slice", "bit", "file", "read", "write", "buffer", "encrypt", "decrypt", "hash", "state", "external", "internal", "float", // anti debug traces "env", "trace", "pid", } /* StripUPXHeaders will ensure no trace of UPX headers are left so that reversing will be more challenging and break simple attempts like "upx -d" in case of compression. */ func StripUPXHeaders(infile string) bool { // Bit sequence of UPX copyright and header infos header := []string{ `\x49\x6e\x66\x6f\x3a\x20\x54\x68\x69\x73`, `\x20\x66\x69\x6c\x65\x20\x69\x73\x20\x70`, `\x61\x63\x6b\x65\x64\x20\x77\x69\x74\x68`, `\x20\x74\x68\x65\x20\x55\x50\x58\x20\x65`, `\x78\x65\x63\x75\x74\x61\x62\x6c\x65\x20`, `\x70\x61\x63\x6b\x65\x72\x20\x68\x74\x74`, `\x70\x3a\x2f\x2f\x75\x70\x78\x2e\x73\x66`, `\x2e\x6e\x65\x74\x20\x24\x0a\x00\x24\x49`, `\x64\x3a\x20\x55\x50\x58\x20\x33\x2e\x39`, `\x36\x20\x43\x6f\x70\x79\x72\x69\x67\x68`, `\x74\x20\x28\x43\x29\x20\x31\x39\x39\x36`, `\x2d\x32\x30\x32\x30\x20\x74\x68\x65\x20`, `\x55\x50\x58\x20\x54\x65\x61\x6d\x2e\x20`, `\x41\x6c\x6c\x20\x52\x69\x67\x68\x74\x73`, `\x20\x52\x65\x73\x65\x72\x76\x65\x64\x2e`, `\x55\x50\x58\x21`, } result := true for _, v := range header { sedString := "" // generate random byte sequence replace := make([]byte, 1) for len(sedString) < len(v) { _, err := rand.Read(replace) if err != nil { return false } sedString += `\x` + hex.EncodeToString(replace) } // replace UPX sequence with random garbage result = ExecCommand("sed", []string{"-i", `s/` + v + `/` + sedString + `/g`, infile}) if !result { return result } } return result } /* StripFile will strip out all unneeded headers from and ELF file in input. */ func StripFile(infile string, launcherFile string) bool { // strip symbols and headers if !ExecCommand("strip", []string{ "-sxX", "--remove-section=.bss", "--remove-section=.comment", "--remove-section=.eh_frame", "--remove-section=.eh_frame_hdr", "--remove-section=.fini", "--remove-section=.fini_array", "--remove-section=.gnu.build.attributes", "--remove-section=.gnu.hash", "--remove-section=.gnu.version", "--remove-section=.gosymtab", "--remove-section=.got", "--remove-section=.note.ABI-tag", "--remove-section=.note.gnu.build-id", "--remove-section=.shstrtab", "--remove-section=.typelink", infile, }) { return false } // ------------------------------------------------------------------------ // proceede with manual // stripping of golang builtins and keyWords strings removeStrings := []string{} removeStrings = append(removeStrings, extras...) // anonymize the launcherFile string to hide the original launcher file name removeStrings = append(removeStrings, launcherFile) // deduplicate removeStrings = Unique(removeStrings) // read file to string byteContent, err := ioutil.ReadFile(infile) if err != nil { return false } input := string(byteContent) for _, remove := range removeStrings { // generate new random string to place instead newName := GenerateNullString(len(remove)) input = strings.ReplaceAll(input, remove, newName) input = strings.ReplaceAll(input, strings.Title(remove), newName) } // save. err = ioutil.WriteFile(infile, []byte(input), 0600) // ------------------------------------------------------------------------ return err == nil } /* GenerateTyposquatName is a typosquat name generator based on a length (128 default) this will create a random uniqe string composed only of letters and zeroes that are lookalike. */ func GenerateTyposquatName(length int) string { // We divide between an alphabet with number // and one without, because function/variable names // must not start with a number. letterRunes := []rune("OÓÕÔÒÖŌŎŐƠΘΟ") mixedRunes := []rune("0OÓÕÔÒÖŌŎŐƠΘΟ") b := make([]rune, length) // ensure we do not start with a number or we will break code. b[0] = letterRunes[Random(0, int64(len(mixedRunes)-1))] for i := range b { if i != 0 { b[i] = mixedRunes[Random(0, int64(len(mixedRunes)-1))] } } return string(b) } /* ObfuscateFuncVars will: - extract all obfuscation-enabled func and var names: - those start with "ob*" and will be listed - for each matching string generate a typosquatted random string and replace all string with that */ func ObfuscateFuncVars(input string) string { // obfuscate functions and variables names regex := regexp.MustCompile(`\bob[a-zA-Z0-9_]+`) words := regex.FindAllString(input, -1) words = ReverseStringArray(words) words = Unique(words) for _, w := range words { // generate random name for each matching string input = strings.ReplaceAll(input, w, GenerateTyposquatName(128)) } return input } /* GenerateStringFunc will hide a string creating a function that returns that value as a string encoded with a series of length calculation of randomic string arrays generated. */ func GenerateStringFunc(txt string, function string) string { resString := "{" for _, b := range []byte(txt) { resString += "\"" + GenerateTyposquatName(int(b)) + "\"" + "," } // remove last comma resString = strings.TrimSuffix(resString, ",") // close array resString += "}" result := fmt.Sprintf("func " + function + "() string {\nobRegistered := []string" + resString + "\nvar obResult []byte\nfor _,obValue := range obRegistered " + "{\nobResult = append(obResult, byte(len([]rune(obValue))))\n}\nreturn string(obResult)\n}") return result } /* ObfuscateStrings will extract all plaintext strings denotet with backticks and obfuscate them using byteshift wise operations. */ func ObfuscateStrings(input string) string { // parse the launcher file to create the list of imports in it imports := strings.Index(input, "import (") endimports := strings.Index(input[imports:], ")") // import section importSection := input[:imports+endimports+1] // the rest of the program body := input[imports+endimports+1:] // various types of string delimiter tickTypes := []string{"`", `'`, `"`} // for each ticktype, try to get all the strings and // obfuscate them using functions for _, v := range tickTypes { regex := regexp.MustCompile(v + ".*?" + v) words := regex.FindAllString(body, -1) words = Unique(words) for _, w := range words { // string not void, accounting for quotes if len(w) > 2 && !strings.Contains(w, `\`) { // add string to the secrets! if not present _, present := Secrets[w] if !present { secret := w[1 : len(w)-1] Secrets[w] = []string{secret, GenerateTyposquatName(128)} } } } } // create function call funcString := "" // replace all secrects with the respective obfuscated string for k, w := range Secrets { // in case we manually added some secrets that we want to leave if !strings.Contains(w[1], "leave") { funcString = funcString + GenerateStringFunc(w[0], w[1]) + "\n" body = strings.ReplaceAll(body, k, w[1]+"()") } else { body = strings.ReplaceAll(body, k, w[0]) } } // reconstruct the program correctly and // insert all the functions before the main body = body + "\n" + funcString // join back with the import section return importSection + body } /* GenerateRandomAntiDebug will Insert random order of anti-debug check together with inline compilation to induce big number of instructions in random order. */ func GenerateRandomAntiDebug(input string) string { lines := strings.Split(input, "\n") randomChecks := []string{ `obDependencyCheck()`, `obEnvArgsDetect()`, `obParentTracerDetect()`, `obParentCmdLineDetect()`, `obEnvDetect()`, `obEnvParentDetect() `, `obLdPreloadDetect()`, `obParentDetect()`, } var obfile []string // find OB_CHECK and put the checks there. for _, v := range lines { if strings.Contains(v, "//") { if strings.Contains(v, "// OB_CHECK") { threadString := "" checkString := "" // randomize order of check to replace for j, v := range ShuffleSlice(randomChecks) { threadString = threadString + "go " + v + ";" checkString += v if j != (len(randomChecks) - 1) { checkString += `||` } } // add action in case of failed check obfile = append(obfile, threadString) continue } else { // remove comment, this is more to scramble the line numbers // and make error reporting less accurate continue } } obfile = append(obfile, v) } // back to single string return strings.Join(obfile, "\n") } /* ObfuscateLauncher the go code of the runner before compiling it. Basic techniques are applied: - GenerateRandomAntiDebug - ObfuscateStrings - ObfuscateFuncVars. */ func ObfuscateLauncher(infile string) error { byteContent, err := ioutil.ReadFile(infile) if err != nil { return fmt.Errorf("failed to read input file: %w", err) } content := string(byteContent) // ------------------------------------------------------------------------ // --- Start anti-debug checks content = GenerateRandomAntiDebug(content) // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // --- Start string obfuscation content = ObfuscateStrings(content) // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // --- Start function name obfuscation content = ObfuscateFuncVars(content) // ------------------------------------------------------------------------ // save. err = ioutil.WriteFile(infile, []byte(content), 0600) if err != nil { return fmt.Errorf("failed to save output file: %w", err) } return nil } ================================================ FILE: internal/pakkero/pakkero.go ================================================ /* Package pakkero will pack, compress and encrypt any type of executable. */ package pakkero import ( "encoding/base64" "encoding/binary" "fmt" "io/ioutil" "os" "os/signal" "strconv" "syscall" "github.com/alegrey91/go-upx" ) const ( offsetPlaceholder = `"9999999"` stdoutEnabledPlaceholder = `"ENABLESTDOUT"` depNamePlaceholder = `"DEPNAME1"` depSizePlaceholder = `"DEPSIZE2"` depBFDPlaceholder = "[]float64{1, 2, 3, 4}" ) var launcherFile = os.TempDir() + "/launcher.go" func cleanup() { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") fmt.Print(" → Cleaning up...") // remove unused file ExecCommand("rm", []string{"-f", launcherFile}) fmt.Printf(SuccessColor, "\t\t\t[ OK ]\n") } func trap() { // Prepare to intercept SIGTERM c := make(chan os.Signal) signal.Notify(c, os.Interrupt, syscall.SIGTERM) go func() { <-c cleanup() os.Exit(ERR) }() } // Pakkero will Encrypt and pack the payload for a secure execution. func Pakkero(infile string, offset int64, outfile string, dependency string, compress bool, stdout bool) { trap() fmt.Print(" → Randomizing offset...") // declare outfile as original filename + .enc if len(outfile) == 0 { outfile = infile + ".enc" } // ------------------------------------------------------------------------ // offset Hysteresis, this will prevent easy key retrieving offset += Random(128, 4094) fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Register Dependency to try and bypass any tampering on dependent // packages fmt.Print(" → Registering Dependencies...") Secrets[stdoutEnabledPlaceholder] = []string{"\"unset\"", "leaveunset"} // ------------------------------------------------------------------------ // Register eventual dependency passed by cli // If a dependency check is present, register it. if dependency != "" { RegisterDependency(dependency) } else { // in case of missing dependency add an empty variable for BFD Secrets[depBFDPlaceholder] = []string{"[]float64{}", "leaveBFD"} } fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Create the launcher program starting from our stub fmt.Print(" → Creating Launcher Stub...") // add offset to the secrets! Secrets[offsetPlaceholder] = []string{ fmt.Sprintf("%d", offset), GenerateTyposquatName(128), } // copy the stub from where to start. launcherStub, _ := base64.StdEncoding.DecodeString(LauncherStub) err := ioutil.WriteFile(launcherFile, launcherStub, 0600) if err != nil { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println(fmt.Sprintf("failed writing to file: %s", err)) cleanup() os.Exit(ERR) } fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Obfuscate the launcher fmt.Print(" → Obfuscating Launcher Stub...") err = ObfuscateLauncher(launcherFile) if err != nil { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println(fmt.Sprintf("failed obfuscating file file: %s", err)) cleanup() os.Exit(ERR) } fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // compile the launcher binary fmt.Print(" → Compiling Launcher...") var flags []string os.Setenv("CGO_ENABLED", "0") flags = []string{ "build", "-a", "-trimpath", "-gcflags", "-N -l -nolocalimports", "-ldflags=" + "-X main.Stdout=" + strconv.FormatBool(stdout) + " -s -w -extldflags -static\"", } flags = append(flags, "-o") flags = append(flags, outfile) flags = append(flags, launcherFile) if ExecCommand("go", flags) { fmt.Printf(SuccessColor, "\t\t[ OK ]\n") } else { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") ExecCommand("rm", []string{"-f", outfile}) cleanup() os.Exit(ERR) } // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Strip File of excess headers fmt.Print(" → Stripping Launcher...") if StripFile(outfile, launcherFile) { fmt.Printf(SuccessColor, "\t\t[ OK ]\n") } else { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") ExecCommand("rm", []string{"-f", outfile}) cleanup() os.Exit(ERR) } // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Compress File of occupy less space // Then remove UPX headers from file. fmt.Print(" → Compressing Launcher...") if compress { options := goupx.Options{ Output: "", Force: false, Verbose: false, } upx := goupx.NewUPX() compression, err := upx.Compress(outfile, 8, options) if err != nil { fmt.Println(err) } if compression && StripUPXHeaders(outfile) { fmt.Printf(SuccessColor, "\t\t[ OK ]\n") } else { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") ExecCommand("rm", []string{"-f", outfile}) cleanup() os.Exit(ERR) } } else { fmt.Printf(WarningColor, "\t\t[ SKIPPING ]\n") } // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Remove unused file fmt.Print(" → Cleaning up...") if ExecCommand("rm", []string{"-f", launcherFile}) { fmt.Printf(SuccessColor, "\t\t\t[ OK ]\n") } else { fmt.Printf(ErrorColor, "\t\t\t[ ERR ]\n") ExecCommand("rm", []string{"-f", outfile}) os.Exit(ERR) } // ------------------------------------------------------------------------ // read compiled file encFile, err := os.OpenFile(outfile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644) if err != nil { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println(fmt.Sprintf("failed writing to file: %s", err)) os.Exit(ERR) } defer encFile.Close() encFileStat, _ := encFile.Stat() encFileSize := encFileStat.Size() // ------------------------------------------------------------------------ // Input validation fmt.Print(" → Verifying input offset...") // Ensure input offset is valid comared to compiled file size! if offset <= encFileSize { ExecCommand("rm", []string{"-f", outfile}) fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println("ERROR! Calculated offset is lower than launcher size: " + fmt.Sprintf("offset=%d, filesize=%d", offset, encFileSize)) os.Exit(ERR) } fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Pre-Payload Garbage // calculate where to put garbage and where to put the payload fmt.Print(" → Adding garbage...") blockCount := offset - encFileSize // append randomness to the runner itself _, err = encFile.WriteString(GenerateRandomGarbage(blockCount)) if err != nil { fmt.Printf(ErrorColor, "\t\t\t[ ERR ]\n") println(fmt.Sprintf("failed writing to file: %s", err)) os.Exit(ERR) } fmt.Printf(SuccessColor, "\t\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Encryption and compression of the payload // get file to encrypt argument fmt.Print(" → Reading payload...") byteContent, err := ioutil.ReadFile(infile) // just pass the file name if err != nil { fmt.Printf(ErrorColor, "\t\t\t[ ERR ]\n") println(fmt.Sprintf("failed reading file: %s", err)) os.Exit(ERR) } content := string(byteContent) // plaintext content plaintext := []byte(base64.StdEncoding.EncodeToString([]byte(content))) fmt.Printf(SuccessColor, "\t\t\t[ OK ]\n") // ------------------------------------------------------------------------ fmt.Print(" → Compressing payload...") // GZIP before encrypt plaintext = GzipContent(plaintext) fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ fmt.Print(" → Encrypting payload...") // encrypt aes256-gcm ciphertext, err := EncryptAESReversed(plaintext, outfile) if err != nil { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println(fmt.Sprintf("failed encrypting file: %s", err)) os.Exit(ERR) } // append payload to the runner itself _, err = encFile.WriteString(ciphertext) if err != nil { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println(fmt.Sprintf("failed writing to file: %s", err)) os.Exit(ERR) } fmt.Printf(SuccessColor, "\t\t[ OK ]\n") // ------------------------------------------------------------------------ // ------------------------------------------------------------------------ // Post-Payload Garbage // calculate final padding fmt.Print(" → Adding garbage to payload...") finalPaddingArray := make([]byte, binary.MaxVarintLen64) n := binary.PutVarint(finalPaddingArray, offset) finalPaddingB := finalPaddingArray[:n] // change endianess to every byte composing // the offset for i := range finalPaddingB { finalPaddingB[i] = ReverseByte(finalPaddingB[i]) } finalPadding, _ := binary.Varint(finalPaddingB) // and ensure it is positive! if finalPadding < 0 { finalPadding *= -1 } // append random garbage equal to bit-reverse of the offset // at the end of the payload _, err = encFile.WriteString(GenerateRandomGarbage(finalPadding)) if err != nil { fmt.Printf(ErrorColor, "\t\t[ ERR ]\n") println(fmt.Sprintf("failed writing to file: %s", err)) os.Exit(ERR) } // ------------------------------------------------------------------------ fmt.Printf(SuccessColor, "\t\t[ OK ]\n") } ================================================ FILE: internal/pakkero/utilities.go ================================================ /* Package pakkero will pack, compress and encrypt any type of executable. Utilities library */ package pakkero import ( "bytes" "compress/zlib" "crypto/rand" "fmt" "io/ioutil" "math/big" "os" "os/exec" ) // Colors for strings. const ( SuccessColor = "\033[1;32m%s\033[0m" WarningColor = "\033[1;33m%s\033[0m" ErrorColor = "\033[1;31m%s\033[0m" ) // ERR Is the exit Code 1. const ERR = 1 // OK Is the exit Code 0. const OK = 0 /* RandomInt64 will return a random number in a range. */ func RandomInt64(max int64) int64 { bg := big.NewInt(max) n, err := rand.Int(rand.Reader, bg) if err != nil { panic(err) } return n.Int64() } /* Random will return a random number in a range. */ func Random(min, max int64) int64 { bg := big.NewInt(max - min) n, err := rand.Int(rand.Reader, bg) if err != nil { panic(err) } // add n to min to support the passed in range return n.Int64() + min } /* Unique will deduplicate a given slice. */ func Unique(slice []string) []string { keys := make(map[string]bool) list := []string{} for _, entry := range slice { if _, value := keys[entry]; !value { keys[entry] = true list = append(list, entry) } } return list } /* ReverseByteArray will reverse a slice of bytes. */ func ReverseByteArray(input []byte) []byte { reversed := []byte{} for i := range input { n := input[len(input)-1-i] reversed = append(reversed, n) } return reversed } /* ReverseByte will change a byte endianess. */ func ReverseByte(b byte) byte { var d byte for i := 0; i < 8; i++ { d <<= 1 d |= b & 1 b >>= 1 } return d } /* ReverseStringArray reverse a slice of strings. */ func ReverseStringArray(ss []string) []string { last := len(ss) - 1 for i := 0; i < len(ss)/2; i++ { ss[i], ss[last-i] = ss[last-i], ss[i] } return ss } /* ReverseString reverse a string. */ func ReverseString(input string) string { var result string for _, value := range input { result = string(value) + result } return result } /* ShuffleSlice will shuffle a slice. */ func ShuffleSlice(in []string) []string { for i := len(in) - 1; i > 0; i-- { j := RandomInt64(int64(i) + 1) in[i], in[j] = in[j], in[i] } return in } /* ExecCommand is a wrapper arount exec.Command to execute a command and ensure it's result is not err. */ func ExecCommand(name string, args []string) bool { cmd := exec.Command(name, args...) errString, err := cmd.CombinedOutput() if err != nil { println(fmt.Sprintf("failed to execute command %s: %s", cmd, err)) println(string(errString)) return false } return true } /* GenerateRandomGarbage creates random garbage to rise entropy. */ func GenerateRandomGarbage(size int64) string { randomGarbage := make([]byte, size) _, err := rand.Read(randomGarbage) if err != nil { panic(err) } return string(randomGarbage) } /* GzipContent an input byte slice and return it compressed. */ func GzipContent(input []byte) []byte { // GZIP before encrypt var zlibPlaintext bytes.Buffer zlibWriter := zlib.NewWriter(&zlibPlaintext) _, err := zlibWriter.Write(input) zlibWriter.Close() if err != nil { panic(err) } return zlibPlaintext.Bytes() } /* GenerateNullString will return a string with only void chars. */ func GenerateNullString(n int) string { result := "" for len(result) < n { result += string(0) } return result } /* RegisterDependency will take a file in input and register the Byte Frequency Distribution (BFD) and some other data to let the launcher do statystical analysis of the found files. */ func RegisterDependency(dependency string) { dependencyFile, _ := os.Open(dependency) defer dependencyFile.Close() dependencyStats, _ := dependencyFile.Stat() depenencyLinkStats, _ := os.Lstat(dependency) if (depenencyLinkStats.Mode() & os.ModeSymlink) != 0 { cleanup() fmt.Printf("Invalid path: %s is a symlink, use absolute paths.\n", dependency) os.Exit(1) } // calculate BFD (byte frequency distribution) for the input dependency bytes, _ := ioutil.ReadFile(dependency) bfd := make([]float64, 256) for _, b := range bytes { bfd[b]++ } // make a string out of it bfdString := "[]float64{" for _, v := range bfd { bfdString += fmt.Sprintf("%f", v) + "," } bfdString += "}" // add Dependency data to the secrets // register BFD Secrets[depBFDPlaceholder] = []string{bfdString, "leaveBFD"} // register name Secrets[depNamePlaceholder] = []string{dependency, GenerateTyposquatName(128)} // register size Secrets[depSizePlaceholder] = []string{ fmt.Sprintf("%d", dependencyStats.Size()), GenerateTyposquatName(128), } } ================================================ FILE: main.go ================================================ /* Package main, calls all the libraries needed and handles cli flags. */ package main import ( "flag" "os" "github.com/89luca89/pakkero/internal/pakkero" ) const ( programName = "pakkero" version = "0.7.0" minArgsLen = 2 ) const ( minOffsetCompressed = 750000 maxOffsetCompressed = 800000 minOffset = 1910000 maxOffset = 2100000 ) var ( dependencies = []string{"ls", "sed", "go", "strip"} dependenciesComplete = []string{"upx", "ls", "sed", "go", "strip"} ) /* TestDependencies if all dependencies are present in the system. */ func testDependencies(deps []string) { for _, v := range deps { if !pakkero.ExecCommand("which", []string{v}) { println("Missing Dependency: " + v) os.Exit(pakkero.ERR) } } } /* Print version. */ func printVersion() { println(programName + " v" + version) os.Exit(pakkero.OK) } /* Print Help. */ func help() { println("Usage: " + programName + " -file /path/to/file -offset OFFSET (-o /path/to/output) (-c) (-register-dep /path/to/file)") println(" -file Target file to Pack") println(" -o place the output into (default is .enc, optional)") println(" -offset Offset where to start the payload (Number of Bytes, optional)") println(" -register-dep Target file to analyze and use as fingerprint (absolute path, optional)") println(" -c compress the output to occupy less space (uses UPX, optional)") println(" -enable-stdout Whether to wait and handle the process stdout/sterr or not (false by default, optional)") println(" -v Check " + programName + " version") } func main() { if len(os.Args) < minArgsLen { help() os.Exit(pakkero.ERR) } flag.Usage = func() { help() } file := flag.String("file", "", "") dependency := flag.String("register-dep", "", "") output := flag.String("o", "", "") offset := flag.Int64("offset", 0, "") compress := flag.Bool("c", false, "") stdout := flag.Bool("enable-stdout", false, "") flag.Bool("v", false, "") flag.Parse() switch os.Args[1] { case "-v": printVersion() default: // fist test if all dependencies are present if *compress { // compression needs additional upx dependency testDependencies(dependenciesComplete) } else { testDependencies(dependencies) } // set a default offset if not specified if *offset == 0 { if *compress { *offset = pakkero.Random(minOffsetCompressed, maxOffsetCompressed) } else { *offset = pakkero.Random(minOffset, maxOffset) } } if *file != "" { pakkero.Pakkero(*file, *offset, *output, *dependency, *compress, *stdout) } else { println("Missing arguments or invalid arguments!") help() os.Exit(pakkero.ERR) } } }