Evasive shellcode loader for bypassing event-based injection detection, without necessarily suppressing event collection (still added direct syscalls, just so I don't have to deal with AV). The project is aiming to highlight limitations of event-driven injection identification, and show the need for more advanced memory scanning and smarter local agent software inventories in EDR.
DripLoader evades common EDRs by:
- using the most risky APIs possible like
- blending in with call arguments to create events that vendors are forced to drop or log&ignore due to volume
- avoiding multi-event correlation by introducing delays
What does DripLoader do
- Identifies a base address suitable for our payload
- Reserves enough
NO_ACCESSmemory segments at the base address
- Loops over those
PageSize(4kB) sized, writable segments
- Writing shellcode
- Reprotecting as
- Overwrites prologue of one
ntdllfunction in the remote process memory space with a
jmpto our base
- Drops a thread on that trampoline
I'll explain some of the thinking here: https://blog.redbluepurple.io/offensive-research/bypassing-injection-detection
- It's able to fully bypass many EDR injection detections, including Defender ATP.
- Bypasses simple thread-centric scanners like
Get-InjectedThread. Persisting within a process is another story, and this is up to the payload author.
- It is
sRDI-compatible, but if your payload creates another local thread you will lose the benefit of thread start address in
To test it out of the box
- XOR your binary shellcode blob file with default key 0x08, name it
- place both files in the same directory
- run it and follow the prompts or ./DripLoader.exe <target_pid> <delay_per_step_ms>
I attached an example
MessageBox blob for your pleasure, be aware though it's size is unrealistically small for a payload.