E9Patch - A Powerful Static Binary Rewriter

E9Patch is a powerful static binary rewriting tool for x86_64 Linux ELF binaries. E9Patch is:

• Scalable: E9Patch can reliably rewrite large/complex binaries including web browsers (>100MB in size).
• Compatible: The rewritten binary is a drop-in replacement of the original, with no additional dependencies.
• Fast: E9Patch can rewrite most binaries in a few seconds.
• Low Overheads: Both performance and memory.
• Programmable: E9Patch is designed so that it can be easily integrated into other projects. See the E9Tool User's Guide and the E9Patch Programmer's Guide for more information.

Static binary rewriting takes an input binary (ELF executable or shared object) and generates an output binary with some patch/modification applied to it. The patched binary can be used as a drop-in replacement of the original.

For more information, please see our PLDI'2020 paper:

• Gregory J. Duck, Xiang Gao, Abhik Roychoudhury, Binary Rewriting without Control Flow Recovery, Programming Language Design and Implementation (PLDI), 2020. PLDI'2020 Presentation

Release

Pre-built E9Patch binaries can be downloaded here:

• https://github.com/GJDuck/e9patch/releases

Build

Building E9Patch is very easy: simply run the build.sh script.

This will automatically build two tools:

1. e9patch: the binary rewriter backend; and
2. e9tool: a linear disassembly frontend for E9Patch.

Example Usage

E9Patch is usable via the E9Tool frontend.

For example, to add instruction printing instrumentation to all xor instructions in xterm, we can use the following command:

    $ ./e9tool -M 'asm=/xor.*/' -P print xterm

This will generate a modified version of xterm written to the a.out file.

The modified xterm can be run as normal, but will print the assembly string of each executed xor instruction to stderr:

    $ ./a.out
    xorl %ebp, %ebp
    xorl %ebx, %ebx
    xorl %eax, %eax
    xorl %edx, %edx
    xorl %edi, %edi
    ...

For a full list of supported options and modes, see:

    $ ./e9tool --help

More Examples

Patch all jump instructions with "empty" instrumentation:

    $ ./e9tool -M 'asm=/j.*/' -P empty xterm
    $ ./a.out

Print all jump instructions with "print" instrumentation:

    $ ./e9tool -M 'asm=/j.*/' -P print xterm
    $ ./a.out

Same as above, but use "Intel" syntax:

    $ ./e9tool -M 'asm=/j.*/' -P print xterm --syntax=intel
    $ ./a.out

Patch all jump instructions with a call to an empty function:

    $ ./e9compile.sh examples/nop.c
    $ ./e9tool -M 'asm=/j.*/' -P 'entry()@nop' xterm
    $ ./a.out

Patch all jump instructions with instruction count instrumentation:

    $ ./e9compile.sh examples/counter.c
    $ ./e9tool -M 'asm=/j.*/' -P 'entry()@counter' xterm
    $ FREQ=10000 ./a.out

Patch all jump instructions with pretty print instrumentation:

    $ ./e9compile.sh examples/print.c
    $ ./e9tool -M 'asm=/j.*/' -P 'entry(addr,instr,size,asm)@print' xterm
    $ ./a.out

Patch all jump instructions with "delay" instrumentation to slow the program down:

    $ ./e9compile.sh examples/delay.c
    $ ./e9tool -M 'asm=/j.*/' -P 'entry()@delay' xterm
    $ DELAY=100000 ./a.out

Notes:

• Tested for XTerm(322)

Projects

Some other projects that use E9Patch include:

• RedFat: A binary hardening system based on low-fat pointers.
• E9AFL: Automatically insert AFL instrumentation into binaries.
• E9Syscall: System call interception using static binary rewriting of libc.so.
• Hopper: Automatic fuzzing test cases generation for libraries.

Documentation

E9Patch is a low-level tool that is designed to be integrable into other projects. To find out more, please see the following documentation:

• E9Patch Programmer's Guide
• E9Tool User's Guide

Bugs

Bugs can be reported here:

• https://github.com/GJDuck/e9patch/issues

Versions

The current version of E9Patch is significantly improved compared to the original prototype evaluated in the PLDI'2020 paper. Specifically:

• The current version implements several new optimizations and can generate significantly faster binaries, sometimes by a factor of 2x. To enable the new optimizations, pass the -O2 option to E9Tool.
• The implementation of the Physical Page Grouping space optimization has also been improved.
• The patching coverage has also been slightly improved.
• Many new features have been implemented (see the documentation).

License

This software has been released under the GNU Public License (GPL) Version 3.

Some specific files are released under the MIT license (check the file preamble).

Acknowledgements

This work was partially supported by the National Satellite of Excellence in Trustworthy Software Systems, funded by National Research Foundation (NRF) Singapore under the National Cybersecurity R&D (NCR) programme.