Sample

Metadata

SHA256
0ad4f87dfa9b814b78e9db2360a89ea7940fb5ad919637bbaacb1222fb44098d
Difficulty
medium
Platform
Windows
Tags
emulation peunion write unpacker anti-emulation
Likes
0
Views
4
Submitter
struppigel

Analysis

Goal

Write an emulation-based unpacker for this crypter. Use the native 32-bit stub and RunPE shellcode. Ignore .NET.

Description

The referenced file is the packer, not the packed file. Pack calc.exe with it, then try to unpack it with your emulation script. I recommend Mandiant's speakeasy for this task.
PEUnion has an in-depth description on Github: https://github.com/bytecode77/pe-union
It features anti-emulation that you need to defeat when writing the unpacker.

Recommended Tools

speakeasy Ghidra

Image

Sample image

Video

Solution by struppigel: Writing an Unpacker for a 3-Stage Stub with Emulation via Speakeasy

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