Cyber security

Titan – VMProtect Devirtualizer

I’m releasing my VMProtect devirtualizer for others to research, learn, and improve. This project started in 2018 as a hobby project and was rewritten at least 4 times.

During my research, I’ve met with awesome people, made friends, and learned a lot. The tool is for educational purposes only, it works for vmprotect < 3.8 but produces less than ideal output.

How Does It Work?

The tool uses Triton for emulation, symbolic execution, and lifting. The easiest way to match VM handlers is to match them on the Triton AST level.

The tool symbolizes vip and vsp registers and propagates memory loads and stores. Almost every handler ends with the store (to the stack, vm register or memory). We take Triton AST of the value that is being stored and match against known patterns:

// Match [vsp] + [vsp].
//
static bool match_add(const triton::ast::SharedAbstractNode& ast)
{
    if (ast->getType() == triton::ast::EXTRACT_NODE)
    {
        return match_add(ast->getChildren()[2]->getChildren()[1]);
    }
    return ast->getType() == triton::ast::BVADD_NODE
        && is_variable(ast->getChildren()[1], variable::vsp_fetch);
}

No matter how obfuscated handlers are, it is possible to match them with a single x86 instruction! Once the handler is identified, it is lifted into a basic block.

Once the basic block is terminated, the partial control-flow graph is computed and the RIP register is sliced, giving the address of the next basic block.

The process repeats until no new basic blocks are found. Every basic block is lifted into separate LLVM function. The process of building control-flow graph comes down chaining calls to basic block functions in the right order.

The tool has few custom LLVM passes like no-alias and memory coalescing passes. The only pass that is left to implement is flag synthesis pass which will give the cleanest LLVM bitcode.

Usage

The tool requires 3 arguments:

  • Path to vmprotect intrinsics file
  • Path to virtualized binary
  • Virtual address of vm entry point
./build/titan
titan: for the -i option: must be specified at least once!
titan: for the -b option: must be specified at least once!
titan: for the -e option: must be specified at least once!
./build/titan -i intrinsics/vmprotect64.ll -b samples/loop_hash.0x140103FF4.exe -e 0x140103FF4

Varshini

Varshini is a Cyber Security expert in Threat Analysis, Vulnerability Assessment, and Research. Passionate about staying ahead of emerging Threats and Technologies.

Recent Posts

Pystinger : Bypass Firewall For Traffic Forwarding Using Webshell

Pystinger is a Python-based tool that enables SOCKS4 proxying and port mapping through webshells. It…

4 days ago

CVE-Search : A Tool To Perform Local Searches For Known Vulnerabilities

Introduction When it comes to cybersecurity, speed and privacy are critical. Public vulnerability databases like…

4 days ago

CVE-Search : A Tool To Perform Local Searches For Known Vulnerabilities

Introduction When it comes to cybersecurity, speed and privacy are critical. Public vulnerability databases like…

4 days ago

How to Bash Append to File: A Simple Guide for Beginners

If you are working with Linux or writing bash scripts, one of the most common…

4 days ago

Mastering the Bash Case Statement with Simple Examples

What is a bash case statement? A bash case statement is a way to control…

4 days ago

How to Check if a File Exists in Bash – Simply Explained

Why Do We Check Files in Bash? When writing a Bash script, you often work…

6 days ago