Finding specific libc function offsets can be a challenging task for developers and security enthusiasts. Whether you’re participating in a CTF competition or debugging an application, knowing the libc version and the function’s actual address is crucial. Traditional methods involve comparing the leaked address with various libc.so versions, which can be time-consuming and inefficient. Fortunately, there’s a new tool that simplifies this process: LibcSearcher.

What is LibcSearcher?

LibcSearcher is a compact and efficient tool developed specifically for CTF competitions. It eliminates the need for manual comparison by automating the search for libc function offsets. Leveraging the powerful libc-database, LibcSearcher provides a comprehensive database of libc versions, making it easier to find the exact offset you need.

Installation and Setup

Getting started with LibcSearcher is straightforward. Follow these simple steps to install it:

1. Clone the repository: git clone https://github.com/lieanu/LibcSearcher.git
2. Move into the cloned directory: cd LibcSearcher
3. Install LibcSearcher: python setup.py develop

Once installed, you’re ready to integrate LibcSearcher into your workflow.

How to Use LibcSearcher

Using LibcSearcher is incredibly intuitive. With just a few lines of code, you can find the offsets for specific libc functions. Here’s an example:

“`python
from LibcSearcher import *

Specify the leaked function and its address (either actual or last 12 bits)

obj = LibcSearcher(“fgets”, 0X7ff39014bd90)

Dump the offset for the desired functions

obj.dump(“system”) # Offset for ‘system’ function
obj.dump(“str_bin_sh”) # Offset for ‘/bin/sh’ string
obj.dump(“__libc_start_main_ret”) # Offset for ‘__libc_start_main_ret’ function
“`

If you encounter multiple libc versions returned, you can use the add_condition(leaked_func, leaked_address) method to add constraints or manually select a libc version if you’re certain about it.

Contributing and Feedback

LibcSearcher welcomes contributions and feedback from the community. If you encounter any bugs or have suggestions for improvement, feel free to share your thoughts. As an open-source project, LibcSearcher thrives on collaboration and strives to serve the needs of developers and security enthusiasts worldwide.

In conclusion, LibcSearcher offers a streamlined approach for finding libc function offsets, saving valuable time and effort. Its support for CTF competitions and easy integration make it an indispensable tool for developers and security professionals alike. By leveraging the power of open source and automation, LibcSearcher empowers users to focus on what matters most – building secure and robust applications.