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 .

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. 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] [-f fix-format] [-e fix-file]

  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.

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

  -e option： Fix parameter 0 value by custom external file.

• Code pattern differences

  The normal mode shell script has some code visibility issues in most Linux operating systems, and the code after the read command 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 supports human-machine interaction in all scripting languages, while some languages in safe mode do not support it, such as csh,tcsh.

  The safe mode human-machine interaction 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

OS	TOOL	SUPPORTED
AIX 7.1	dbx sdb	YES
SCO UNIX 5.0.6	dbx sdb adb	YES
Red Hat Linux7.8	gdb	YES
CentOS Linux6.4	gdb	YES
debian 12.4.0	gdb	YES
Fedora 39	gdb lldb	YES
FreeBSD 14.0	gdb	YES
openSUSE Leap 15.5	gdb	YES
OracleLinux R9	gdb	YES
ubuntu 22.04.3	gdb lldb	YES
openEuler	gdb	YES
Debian	gdb	YES
NetBSD 10.0	gdb	NO
DragonFly 6.4	gdb	NO
macOS 13	lldb	NO

History

• 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