lscan

lscan is a tool which identifies library in statically linked/stripped binaries. The tool is useful for the reverse engineering and computer forensics. It helps recognizing common functions in compiled binaries and determining libraries they are using. lscan uses FLIRT (Fast Library Identification and Recognition Technology) signatures to perform library identification.

Install

If you want to use lscan, you have to install pyelftools and pefile first.

After pyelftools and pefile are installed, lscan can be used as a standalone tool

$python lscan.py [-h] [-f BINFILE] [-s SIGFILE] [-S SIGDIR] [-v]

Usage

$lscan.py

Options:

-h, --help show this help message and exit
-v, --versbose Verbose mode
-s SIGFILE, --sig=SIGFILE
Signature file -S SIGDIR, --sigs=SIGDIR
Signature folder -f BINFILE, --file=BINFILE
ELF file

Example:

$python lscan.py -S i386/sig -f i386/bin/bin-libc-2.23

$python lscan.py -s i386/sig/libpthread-2.23.sig -f i386/bin/bin-libpthread-2.23 -v

$python lscan.py -f i386/win32/bin/bin-libcmt.exe -s i386/win32/sig/msvcmrt.sig

Demo

Reverse Engineer a stripped binary with lscan and IDApro.

A community driven collection of IDA FLIRT signature

• Database 1
• Database 2

Updating sig database

To generate sig files and add them to lscan fig database you need Hex-Rays flair toolkit.

Generate the pat file

$./pelf /usr/lib/libc.a libc.pat

Generate the sig file from the pat file

$./sigmake libc.pat libc.sig

Optionally Use -n parameter to specify the library name.

Collisions may occurs while generating the sig file. In this case a libc.exc file will be created. To resolve the conflicts you must edit the .exc and add '+' at the start of the line to keep a module or '-' if you are not sure about the selection. Do nothing if you want to exclue all the modules. After resolving the conflicts run the above command again. Finnaly copy the libc.sig file to lscan's sig folder.

For coff lib format use pcf instead of pelf

$./pcf libcmt.lib libcmt.pat

Changelog

Version 0.6 (2017-01-19)

• Add support for FLIRT signatures >= v10

Version 0.5 (2016-06-26)

• Added support to PE binaries

Version 0.4 (2016-06-19)

• Bug fix: handling tail bytes, type mismatch in comparison
• Bug fix: Regex, search method replaced by finditer method to iterate through all node pattern matches
• Bug fix: handling tail bytes, iterate through all functions in module having tail bytes
• Handling modules with crc length = 0 and crc = 0 espacially for small functions

Version 0.3 (2016-03-28)

• Support for stripped binary
• Introduced deep match mode
• Better ELF parsing (function offsets)

Version 0.2 (2016-03-23)

• Added support for compressed signtaure files
• Added support to FLIRT functions offset
• Load multiple signature files
• More information output (function offset+names)
• Updated the command line layout and help messages

Version 0.1(2016-03-20)

• First release

Authors

• Marouene Boubakri <[email protected]>