/mixedbooleanarithmeticspayload

Primary LanguageC++

Proof of concept reverse shell with mixed boolean arithmetics

All I did was execute ordinal-loading using the MAKEINTRESOURCE macro. I took the ordinal, and added 4096 1's to it, and then subtracted 4096 1's to deobfuscate it.

5/69 detections Sun Mar 19 07:03:18 PM PDT 2023

https://www.virustotal.com/gui/file/ec9506794c9b622afdcc74e2c70b49020c0b2cebb4819d08d0ec6ceb5573339e/behavior New Payload https://www.virustotal.com/gui/file/e37a602ba7320e5b62ae97db75285eef4fb51dbff7dfa4a863718a1c163a449d?nocache=1

Resources used

  1. PE-Bear
  2. Any IDE is fine
  3. learn.microsoft.com

Compile

x86_64-w64-mingw32-g++ -lwsock32 -lws2_32 revshell.cpp

Why cant you compile it?

I don't want it flagged as malware on Github. Use this as a learning tool.

Notes

This is not real "mixed boolean arithmetics". It's just arithmetics actually. (Fixed with newest update, very simple XOR + Arithmetics)

  1. I did not use bitwise operators to further obfuscate my ordinals (I just did, check new VirusTotal link)
  2. I did not use more convoluted tricks like shifting the bits or rotating them
  3. I kept it simple to demonstrate how to easily bypass antivirus
  4. Part of the reason why it can evade AV despite it's malicious behavior is, outside of hiding the IAT Table and using Ordinal Loading via Mixed Boolean Arithmetics, is it's LOW ENTROPY (0.3x average). Factors like encryption (for sRDI or shellcode reflective DLL injection), obfuscation, can add to entropy, which must be "flattened" by appending useless Windows DLLs with the type command to flatten the entropy score. The metric is vague, but... anything over 0.7 of entropy is considered suspicious and may require a closer look by AV/EDR/XDR Solutions.
  5. In other words, a considerable greater effort must be invested in full blown implants in obfuscating them. Either by appending useless binaries, or by creating unreachable code sections like control-flow flattened loops that can never be reached due to a opaque predicate.
  6. HeavensGate + HellsGate/HalosGate was not used.

Applying simple mixed boolean arithmetics to a example implant (ThreadContext Injection)

Combination of IAT-hiding and ordinal load via mixed boolean arithmetics

Use multiples of 0x1000 to ordinal load these and XOR it back

  1. XOR out the value to a multiple of 0x1000
  2. Compute the value of that multiple in a for-loop
  3. The final ordinal is resolved as the ordinals listed below
  4. Remember these are functions from kernel32.dll

(WriteProcessMemory) Remember that 99 is decimal, not hex, so #define XORKEY 99

0x637 + 0x2000 = 0x2637^99 = 0x2654

(VirtualAllocEx)

0x5e3 + 0x2000 = 0x25e3^99 = 0x2580

SetThreadContext

0x56f p/x (0x2000+0x56f)^99 = 0x250c

SuspendThread

0x5a1 p/x (0x2000+0x5a1)^99 = 0x25c2

GetThreadContext

0x30d p/x (0x2000+0x30d)^99 = 0x236e

SetThreadContext

0x56f p/x (0x2000+0x56f)^99 = 0x250c

CreateToolhelp32Snapshot

0x108 p/x (0x2000+0x108)^99 = 0x216b

Example deobfuscator before MAKEINTRESOURCE macro is used.

#define XORKEY 99

int deobfuscate(int x) {
    x ^= XORKEY;
    for (int i = 0; i < 0x2000; i++) {
        x -= 0x1;
    }
    return x;
}

Added my IS330 Class Papers as PDF files

So this was my IS330 project, which the instructor never asked me to create a producible application (or malware), but I did do it anyways. The whole point of the class was about "innovation", which is a word that I dislike, but I had to "run with it" to get a passing grade.

Anyways, I am working on integrating the following capabilities into my payload (I have already moved on from simple reverse shells to modular shellcode runners with PPID-Spoofing, EDR/XDR Unhooks, Module-Stomps, Virtual-Machine Obfuscation, Global-Hooks, Automated Rootkit Drops, Analyst Punishing Techniques, Self-Instrumentation of payloads to evade analysis, etc.)

If you saw my YouTube Channel (the links are in the bottom of my paper), you know that I am actively working on integrating all of these. I currently have a 32-bit Stack Machine working on *nix operating systems, and will be making adaptions to ensure that it can reliably run on Windows operating systems as a 64-bit process (which requires adaptions to the amd64 calling conventions)

Please refer to pages 12 to 14, as that was where I actually put in effort in implementation. Currently working on...

  1. Self-Instrumenting Stack Machine Obfuscation
  2. Analyst-Punishing
  3. A "emitter" to patch payloads with rogue-byte interweaves to break static analysis tools like IDA and GHIDRA (GHIDRA has proven to be incredibly resilient, even against movfuscated code) https://github.com/xoreaxeaxeax/movfuscator by Christopher Domas