reverse-engineer

SKILL.md

Common RE scripting environments

IDAPython (IDA Pro scripting)

Ghidra scripting (Java/Python via Jython)

r2pipe (radare2 Python API)

pwntools (CTF/exploitation toolkit)

capstone (disassembly framework)

keystone (assembly framework)

unicorn (CPU emulator framework)

angr (symbolic execution)

Triton (dynamic binary analysis)

## Use this skill when

- Working on common re scripting environments tasks or workflows
- Needing guidance, best practices, or checklists for common re scripting environments

## Do not use this skill when

The task is unrelated to common re scripting environments

You need a different domain or tool outside this scope

Instructions

Clarify goals, constraints, and required inputs.

Apply relevant best practices and validate outcomes.

Provide actionable steps and verification.

If detailed examples are required, open resources/implementation-playbook.md.

Analysis Methodology

Phase 1: Reconnaissance

File identification: Determine file type, architecture, compiler

Metadata extraction: Strings, imports, exports, resources

Packer detection: Identify packers, protectors, obfuscators

Initial triage: Assess complexity, identify interesting regions

Phase 2: Static Analysis

Load into disassembler: Configure analysis options appropriately

Identify entry points: Main function, exported functions, callbacks

Map program structure: Functions, basic blocks, control flow

Annotate code: Rename functions, define structures, add comments

Cross-reference analysis: Track data and code references

Phase 3: Dynamic Analysis

Environment setup: Isolated VM, network monitoring, API hooks

Breakpoint strategy: Entry points, API calls, interesting addresses

Trace execution: Record program behavior, API calls, memory access

Input manipulation: Test different inputs, observe behavior changes

Phase 4: Documentation

Function documentation: Purpose, parameters, return values

Data structure documentation: Layouts, field meanings

Algorithm documentation: Pseudocode, flowcharts

Findings summary: Key discoveries, vulnerabilities, behaviors

Response Approach

When assisting with reverse engineering tasks:

Clarify scope: Ensure the analysis is for authorized purposes

Understand objectives: What specific information is needed?

Recommend tools: Suggest appropriate tools for the task

Provide methodology: Step-by-step analysis approach

Explain findings: Clear explanations with supporting evidence

Document patterns: Note interesting code patterns, techniques

Code Pattern Recognition

Common Patterns

// String obfuscation (XOR)
for (int i = 0; i < len; i++)
    str[i] ^= key;

// Anti-debugging (IsDebuggerPresent)
if (IsDebuggerPresent())
    exit(1);

// API hashing (common in malware)
hash = 0;
while (*name)
    hash = ror(hash, 13) + *name++;

// Stack string construction
char s[8];
*(DWORD*)s = 0x6C6C6548;  // "Hell"
*(DWORD*)(s+4) = 0x6F;     // "o\0"

Calling Conventions

x86 cdecl: Args on stack, caller cleans

x86 stdcall: Args on stack, callee cleans

x64 Windows: RCX, RDX, R8, R9, then stack

x64 System V: RDI, RSI, RDX, RCX, R8, R9, then stack

ARM: R0-R3, then stack

Security & Ethics

Authorized Use Only

Security research with proper authorization

CTF competitions and educational challenges

Malware analysis for defensive purposes

Vulnerability disclosure through responsible channels

Understanding software for interoperability

Never Assist With

Unauthorized access to systems

Creating malware for malicious purposes

Bypassing software licensing illegitimately

Intellectual property theft

Any illegal activities

Example Interactions

CTF Binary Challenge

User: "I have a CTF binary that asks for a password. How do I approach this?"

Response: Let me guide you through the analysis:

1. First, identify the binary type:
   $ file challenge
   $ checksec --file=challenge

2. Load in Ghidra/IDA and find main()

3. Look for:
   - String comparisons (strcmp, memcmp)
   - Crypto functions (xor loops, constants like 0x5A827999)
   - Input validation logic

4. Set breakpoints on comparison functions in GDB:
   $ gdb ./challenge
   (gdb) break strcmp
   (gdb) run

5. Examine memory at comparison point to see expected value

Library Analysis

User: "I need to understand how this closed-source DLL handles authentication"

Response: For authorized analysis of the DLL:

1. Static analysis:
   - List exports: dumpbin /exports library.dll
   - Find auth-related functions by name patterns
   - Load in IDA/Ghidra, analyze exported functions

2. Dynamic analysis:
   - Hook API calls with Frida
   - Monitor network traffic
   - Trace function parameters

3. Documentation:
   - Document function signatures
   - Map data structures
   - Note any security considerations

Limitations

Use this skill only when the task clearly matches the scope described above.

Do not treat the output as a substitute for environment-specific validation, testing, or expert review.

Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.