BackdoorFactory - Patch PE (x86/x64) and ELF (x86/x64 and ARM LE x32) binaries with shellcode

Monday, August 4, 2014

Patch win86/64 PE and linux86/64 binaries with shellcode. The goal of The Backdoor Factory is to patch executable binaries with user desired shellcode and continue normal execution of the binary prepatched state. Under a BSD 3 Clause License.

This is done by either appending a code cave or using existing code caves of the executable. This project includes several customized metasploit shellcodes. Plus a new shellcode loadliba_reverse_tcp: designed to bypass all the protections of EMET 4.1. Also, the user can provide their own shellcode for use.

This update provides the loadliba_reverse_tcp shellcode, stability fixes, and speed improvements.

Usage: backdoor.py [options]

Options:
  -h, --help            show this help message and exit
  -f FILE, --file=FILE  File to backdoor
  -s SHELL, --shell=SHELL
                        Payloads that are available for use.
  -H HOST, --hostip=HOST
                        IP of the C2 for reverse connections
  -P PORT, --port=PORT  The port to either connect back to for reverse shells
                        or to listen on for bind shells
  -J, --cave_jumping    Select this options if you want to use code cave
                        jumping to further hide your shellcode in the binary.
  -a, --add_new_section
                        Mandating that a new section be added to the exe
                        (better success) but less av avoidance
  -U SUPPLIED_SHELLCODE, --user_shellcode=SUPPLIED_SHELLCODE
                        User supplied shellcode, make sure that it matches the
                        architecture that you are targeting.
  -c, --cave            The cave flag will find code caves that can be used
                        for stashing shellcode. This will print to all the
                        code caves of a specific size.The -l flag can be use
                        with this setting.
  -l SHELL_LEN, --shell_length=SHELL_LEN
                        For use with -c to help find code caves of different
                        sizes
  -o OUTPUT, --output-file=OUTPUT
                        The backdoor output file
  -n NSECTION, --section=NSECTION
                        New section name must be less than seven characters
  -d DIR, --directory=DIR
                        This is the location of the files that you want to
                        backdoor. You can make a directory of file backdooring
                        faster by forcing the attaching of a codecave to the
                        exe by using the -a setting.
  -w, --change_access   This flag changes the section that houses the codecave
                        to RWE. Sometimes this is necessary. Enabled by
                        default. If disabled, the backdoor may fail.
  -i, --injector        This command turns the backdoor factory in a hunt and
                        shellcode inject type of mechinism. Edit the target
                        settings in the injector module.
  -u SUFFIX, --suffix=SUFFIX
                        For use with injector, places a suffix on the original
                        file for easy recovery
  -D, --delete_original
                        For use with injector module.  This command deletes
                        the original file.  Not for use in production systems.
                        *Author not responsible for stupid uses.*
  -O DISK_OFFSET, --disk_offset=DISK_OFFSET
                        Starting point on disk offset, in bytes. Some authors
                        want to obfuscate their on disk offset to avoid
                        reverse engineering, if you find one of those files
                        use this flag, after you find the offset.
  -S, --support_check   To determine if the file is supported by BDF prior to
                        backdooring the file. For use by itself or with
                        verbose. This check happens automatically if the
                        backdooring is attempted.
  -M, --cave-miner      Future use, to help determine smallest shellcode
                        possible in a PE file
  -q, --no_banner       Kills the banner.
  -v, --verbose         For debug information output.
  -T IMAGE_TYPE, --image-type=IMAGE_TYPE
                        ALL, x32, or x64 type binaries only. Default=ALL
  -Z, --zero_cert       Allows for the overwriting of the pointer to the PE
                        certificate table effectively removing the certificate
                        from the binary for all intents and purposes.
  -R, --runas_admin     Checks the PE binaries for 'requestedExecutionLevel
                        level="highestAvailable"'. If this string is included
                        in the binary, it must run as system/admin. Doing this
                        slows patching speed significantly.
  -L, --patch_dll       Use this setting if you DON'T want to patch DLLs. 
                        Patches by default.

Features:

PE Files

Can find all codecaves in an EXE/DLL.
By default, clears the pointer to the PE certificate table, thereby unsigning a binary.
Can inject shellcode into code caves or into a new section.
Can find if a PE binary needs to run with elevated privileges.
When selecting code caves, you can use the following commands:
  -Jump (j), for code cave jumping
  -Single (s), for patching all your shellcode into one cave
  -Append (a), for creating a code cave
  -Ignore (i), nevermind, ignore this binary
Can ignore DLLs.

ELF Files

Extends 1000 bytes (in bytes) to the TEXT SEGMENT and injects shellcode into that section of code.

Overall

The user can :
  -Provide custom shellcode.
  -Patch a directory of executables/dlls.
  -Select x32 or x64 binaries to patch only.
  -Include BDF is other python projects see pebin.py and elfbin.py




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