Binary String Toolkit
Summary
The Binary String Toolkit or BST for short is a rather simple utility to convert binary strings to various formats suitable for inclusions in source codes, such as those used to develop exploits and Proof of Concepts in the security field.
Features
- Convert and dump binary files to standard output in a binary string format.
- Convert a plain hexadecimal input string to an hex escaped version.
- Generate a sequence of bad characters for detecting bad chars in buffers.
- Limit the width of binary strings for a better readability of your exploit codes.
- Format binary strings in your favorite programming or scripting language's syntax, such as:
- C/C++
- Python
- PowerShell
- Perform automatic variable block indentation ready for copy/paste inclusions.
Dependencies
- POSIX C Library
- C Compiler
- GCC
- LLVM Clang
- GNU Make
- Git
Building
To build and install the 'bstrings' binary on your system, simply do:
$ git clone https://github.com/e3prom/bst
$ cd bst
$ make
# by default, bstrings is installed in /usr/local/bin.
$ sudo make install
Usage
The below example show how an assembled shellcode can be quickly dumped (-D) to standard output in a hexadecimal escaped (-x) binary string of 16 hexadecimal digits width (or 8 bytes), with Python syntax formatting and an indentation level of 4 space characters:
$ bstrings --verbose -x -D lnx-execve-setreuid-x86_64 -w8 -i 4 --syntax=python
[*] Convert hexadecimal input to an escaped binary string.
[+] Binary string width is limited to 8 bytes.
[+] Output binary string using python language syntax.
[+] Indentation level set to 4 space character(s).
shellcode = ""
shellcode += "\x31\xc0\x48\x89\xc7\x48\x89\xc6"
shellcode += "\x48\x89\xc2\xb0\x71\x0f\x05\x31"
shellcode += "\xc0\x50\x48\xbb\x2f\x62\x69\x6e"
shellcode += "\x2f\x2f\x73\x68\x53\x48\x89\xe7"
shellcode += "\x50\x48\x89\xe6\x57\x48\x89\xe2"
shellcode += "\xb0\x3b\x0f\x05"
You can also use bstrings to output an automatically indented bad character sequence, and thus in your favorite programming language:
$ bstrings --verbose -b -w12 -i 4 --syntax=c -n badchar
[*] Generating bad character binary string.
[+] Binary string width is limited to 12 bytes.
unsigned char badchar[] =
"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c"
"\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18"
"\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24"
"\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30"
"\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c"
"\x3d\x3e\x3f\x40\x41\x42\x43\x44\x45\x46\x47\x48"
"\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50\x51\x52\x53\x54"
"\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60"
"\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c"
"\x6d\x6e\x6f\x70\x71\x72\x73\x74\x75\x76\x77\x78"
"\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80\x81\x82\x83\x84"
"\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90"
"\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c"
"\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8"
"\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4"
"\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0"
"\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc"
"\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8"
"\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4"
"\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0"
"\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc"
"\xfd\xfe\xff"
For a list of supported command-line options, simply execute bstrings with the --help switch:
$ bstrings --help
Usage: bstrings [OPTION]...
Convert input to specified binary string format.
At least one of the below options must be given:
-D, --dump-file=FILE Convert and Dump RAW content of file FILE
-x, --hex-escape Escape input hexadecimal string
-b, --gen-badchar Generate a bad character sequence string
The below switches are optional:
-f, --file=FILE Read hex input from file FILE instead of stdin
-w, --width=BYTES Break binary strings to specified length in bytes
-s, --syntax=LANG Output variable using syntax of LANG
-i, --indent=LENGTH Perform indentation for given character length
-n, --var-name=VAR Specify string variable name (verbose mode)
-h, --help Display this help
--interactive Enter interactive mode
--verbose Enable verbose output
--version Print version information
The below languages are supported (case-sensitive):
C C Programming Language
python Python Programming Language
powershell PowerShell Automation and Scripting Language
Contribution
Feel free to contribute to this project by submitting your codes and by reporting issues and bugs
Software License
This software is licensed under the terms of the GNU General Public License.