shellc

Tool for converting scripts into C code

Install

cc shellc.c -O2 -o shellc

Compile shell scripts and generate executable programs

shellc sh example.sh
cc example.sh.c -O2 -o example

The generated C code is example.sh.c, which is the original file name followed by .c. For programs used in production environments, it is recommended to add the parameter -s or use the strip command after compilation to remove the symbol table in the executable program, increasing the difficulty of disassembly and reverse engineering.

I have tried the tools shc, which can compile shell scripts into executable programs. The main problems are:

The shc command actually calls the sh -c command. The source code can be seen through the ps -ef command. The length of the shell script cannot exceed ARG_MAX. Obtaining script source code through methods such as forging interpreters or memory dumps (currently, all tools for converting scripts to C code on GITHUB have this vulnerability).

Shellc not only solves the problems that exist in shc, shellc also adds code obfuscation, randomly generating effective character position calculation functions, random character encryption, and debugging to increase the complexity of disassembly and reverse engineering.If further difficulty is required, professional tools such as obfuscator-llvm can be used to further obfuscate the generated C code.

Version 1.0 or above not only support shell, but also other scripting languages, which can completely replace shc. Version 1.6 adds the function of obtaining script source code through anti-counterfeiting interpreter or memory dump. The anti-counterfeiting interpreter needs to enable the -a or -i option. At present, the program has practical applications in AIX, UNIX, Linux environments. It is recommended to conduct comprehensive testing on the compiled program to prevent production failures.

User manual

• Generate C code command

  shellc command inputfile [-t] [-s] [-a] [-f fix-format] [-e fix-file] [-p parameter] [-b 8|16|32|64] [-i interpreter]

  command： Execute script commands, such sh,perl,python,node,ruby,Rscript,php, etc.

  inputfile： Script file name

  -t option： For systems that do not support anti debugging functionality, this option is required for generated code.

  -s option： Generate C code mode, the -s option uses safe mode, and defaults to normal mode.

  -a option: Anti forgery interpreter requires the MD5 value of the interpreter in the runtime environment to be the same as that of the interpreter in the compilation environment.

  -f option： Fix parameter 0 value or safe mode external parameter.

  -e option： Fix parameter 0 value by custom external file, The definition of safe mode alias needs to be written in an external file.

  -p option： Command parameter, such as busybox shell using by shellc busybox example.sh -p sh.

  -b option： Operating system bits setting.

  -i option: Built in interpreter, interpreter is the file name corresponding to the runtime environment, such as /usr/bin/sh, or a custom file name can be used, such as /tmp/myshell. If there is no corresponding interpreter in the runtime environment, the interpreter file will be automatically generated at runtime. Built in interpreter with anti-counterfeiting function.

• Code pattern differences

  The normal mode shell script has code visibility issues, can be obtained through /proc/[pid]/fd/[pipe]. The safe mode does not have this issue.

  The normal mode supports semaphore processing in scripts, while the safe mode does not support it.

  The normal mode requires that the script length cannot exceed the pipeline buffer value, which is generally 64K for 64 bit systems. Safe mode does not have this issue.

  The normal mode supports human-machine interaction in all scripting languages, while some languages in safe mode do not support it, such as csh,tcsh.

  Version 1.7 of the safe mode human-machine interaction SHELL does not require code modification, while versions 1.6 and below needs to be modified to read from the device /dev/tty. such as shell script read input needs to be changed to read input</dev/tty, For other languages, refer to the test/test_input.*. The normal mode does not require code modification.

  The safe mode and normal mode support different script language types, which can be checked by running test/run.sh.

• Fix arguments

  Fix arguments 0 supports BASH, FISH, ZSH, PERL, PYTHON, JAVASCRIPT, LUA, RUBY.

  In addition to built-in fix format, external file can also be used to fix arguments 0. File format：?Indicates parameter 0 value, line breaks must be explicitly used\n, Double quotes require an escape character \.Reference test/fix.txt.

  Safe mode non definable function shell language external parameter call, requires specifying fix format, such as FISH, PERL,PYTHON, JAVASCRIPT,LUA, RUBY, CSH, TCLSH, PHP,RC.

Untraceable

Version 0.3 or above has added untraceable and tested the following tools for untraceable

History

• v1.7 2024-09-18

  Fix Issue # 18

  Safe mode SHELL human-machine interaction support does not modify the source script program

  Add support for safe mode aliases

• v1.6.2 2024-09-01

  Fix memory overflow

• v1.6.1 2024-09-01

  Fix the array length to be empty

• v1.6 2024-09-01

  Add built-in interpreter

  Add anti-counterfeiting interpreter

  Add anti memory dump

• v1.5 2024-08-25

  Fix the incorrect exit status issue in safe mode

• v1.4 2024-08-17

  Fix memory leak

• v1.3 2024-06-28

  Add command parameter

• v1.2 2024-06-22

  Add operating system bits setting

• v1.1 2024-06-12

  Expand functions in safe mode

• v1.02 2024-06-06

  Removing macro definitions from generated code makes it easier for professional tools to generate more complex and confusing code

• v1.01 2024-06-02

  Remove special handling of FreeBSD

• v1.0 2024-06-01

  Add support for non SHELL scripting languages

  Add fix parameter 0

  Remove BSD and LINUX variant system thread requirements

• v0.3 2023-12-25

  Add untraceable

  Fix compilation warnings in some systems

• v0.21 2023-12-13

  Fix program bugs in the zsh environment

• v0.2 2023-12-12

  Changing the data structure from a structured structure to a string array reduces compilation time for large files

  Add code character encryption function

• v0.1 2023-12-01

  Initial version