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https://github.com/DavidBuchanan314/dlinject
Inject a shared library (i.e. arbitrary code) into a live linux process, without ptrace
https://github.com/DavidBuchanan314/dlinject
assembly ld-preload linux procfs ptrace python3 shellcode shellcode-injection x86-64
Last synced: about 1 month ago
JSON representation
Inject a shared library (i.e. arbitrary code) into a live linux process, without ptrace
- Host: GitHub
- URL: https://github.com/DavidBuchanan314/dlinject
- Owner: DavidBuchanan314
- License: mit
- Created: 2019-12-30T04:08:11.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2022-06-10T02:54:26.000Z (over 2 years ago)
- Last Synced: 2024-10-30T06:58:44.473Z (about 1 month ago)
- Topics: assembly, ld-preload, linux, procfs, ptrace, python3, shellcode, shellcode-injection, x86-64
- Language: Python
- Size: 45.9 KB
- Stars: 773
- Watchers: 23
- Forks: 75
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# dlinject.py
Inject a shared library (i.e. arbitrary code) into a live linux process, without ptrace. Inspired by [Cexigua](https://github.com/AonCyberLabs/Cexigua) and [linux-inject](https://github.com/gaffe23/linux-inject), among other things.
[](https://asciinema.org/a/290906)
# Usage
```
.___.__ .__ __ __
__| _/| | |__| ____ |__| ____ _____/ |_ ______ ___.__.
/ __ | | | | |/ \ | |/ __ \_/ ___\ __\ \____ < | |
/ /_/ | | |_| | | \ | \ ___/\ \___| | | |_> >___ |
\____ | |____/__|___| /\__| |\___ >\___ >__| /\| __// ____|
\/ \/\______| \/ \/ \/|__| \/
source: https://github.com/DavidBuchanan314/dlinject
usage: dlinject.py [-h] [--stopmethod {sigstop,cgroup_freeze,none}]
pid /path/to/lib.so
Inject a shared library into a live process.
positional arguments:
pid The pid of the target process
/path/to/lib.so Path of the shared library to load (note: must be
relative to the target process's cwd, or absolute)
optional arguments:
-h, --help show this help message and exit
--stopmethod {sigstop,cgroup_freeze,none}
How to stop the target process prior to shellcode
injection. SIGSTOP (default) can have side-effects.
cgroup freeze requires root. 'none' is likely to cause
race conditions.
```
# Why?
- Because I can.
- There are various [anti-ptrace techniques](https://www.aldeid.com/wiki/Ptrace-anti-debugging), which this evades by simply not using ptrace.
- I don't like ptrace.
- Using `LD_PRELOAD` can sometimes be fiddly or impossible, if the process you want to inject into is spawned by another process with a clean environment.
# How it Works
- Send the stop signal to the target process. (optional)
- Locate the `_dl_open()` symbol.
- Retreive `RIP` and `RSP` via `/proc/[pid]/syscall`.
- Make a backup of part of the stack, and the code we're about to overwrite with our shellcode, by reading from `/proc/[pid]/mem`.
- Generate primary and secondary shellcode buffers.
- Insert primary shellcode at `RIP`, by writing to `/proc/[pid]/mem`.
- The primary shellcode:
- Pushes common registers to the stack.
- Loads the secondary shellcode via `mmap()`.
- Jumps to the secondary shellcode.
- The secondary shellcode:
- Restores the stack and program code to their original states.
- Pivots the stack (so we don't touch the original one at all).
- Calls `_dl_open()` to load the user-specified library. Any constructors will be executed on load, as usual.
- Restores register state, un-pivots the stack, and jumps back to where it was at the time of the original `SIGSTOP`.
# Limitations:
- Sending `SIGSTOP` may cause unwanted side-effects, for example if another thread is waiting on `waitpid()`. The `--stopmethod=cgroup_freeze` option avoids this, but requires root (on most distros, at least).
- I'm not entirely sure how this will interact with complex multi-threaded applications. There's certainly potential for breakage.
- `x86-64` Linux only (for now - 32-bit support could potentially be added).
- Requires root, or relaxed YAMA configuration (`echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope` is useful when testing).
- If the target process is sandboxed (e.g. seccomp filters), it might not have permission to `mmap()` the second stage shellcode, or to `dlopen()` the library.