Detecting Use After Free

Use-After-Free Detection

Detection Workflow

1. Identify free operations: Find all free(), realloc(), delete calls and note the pointer being freed
2. Trace pointer usage: Use xrefs_to to find all dereferences of the pointer
3. Check control flow: Analyze paths through code to identify usage after free
4. Assess exploitability: Can attacker control freed memory? Is there a useful use-after-free? Can memory be reallocated?

Key Patterns

• Pointer dereference after free()
• Double free vulnerabilities
• Invalid pointer access after realloc()
• Reference counting issues

Output Format

Report with: id, type, subtype, severity, confidence, location, freed pointer, free operation, use operation, use-after-free status, distance, exploitability, attack scenario, impact, mitigation.

Severity Guidelines

• CRITICAL: Use-after-free with code execution
• HIGH: Use-after-free with data corruption
• MEDIUM: Use-after-free causing crashes
• LOW: Use-after-free with limited impact

See Also

• patterns.md - Detailed detection patterns and exploitation scenarios
• examples.md - Example analysis cases and code samples
• references.md - CWE references and mitigation strategies