detecting-signed-unsigned-conversion

name	detecting-signed-unsigned-conversion
description	Detects unsafe signed/unsigned integer conversions that can lead to integer overflow and security check bypasses. Use when analyzing integer operations, comparisons, or investigating conversion-related vulnerabilities.

Signed/Unsigned Conversion Detection

Detection Workflow

1. Identify conversions: Find all signed/unsigned conversions, locate implicit conversions, identify comparison operations, map arithmetic operations
2. Analyze conversion safety: Check for negative values, assess overflow potential, verify conversion correctness, review comparison logic
3. Trace value flow: Follow values through conversions, identify impact on operations, assess security implications, verify value constraints
4. Assess exploitability: Can attacker trigger negative value? Can conversion bypass security checks? What's the potential impact? Is it exploitable?

Key Patterns

• Comparison errors: comparing signed with unsigned values, negative values treated as large positive, bypassed bounds checks, incorrect loop conditions
• Arithmetic errors: signed to unsigned conversion in arithmetic, integer overflow after conversion, underflow after conversion, unexpected results
• Function parameter issues: passing signed to unsigned parameters, implicit conversions in function calls, missing explicit casting, type mismatch in APIs
• Size calculation issues: signed values used for sizes, negative sizes after conversion, overflow in size calculations, incorrect buffer allocations

Output Format

Report with: id, type, subtype, severity, confidence, location, vulnerability, comparison_operation, signed_variable, unsigned_variable, issue, exploitable, attack_scenario, impact, mitigation.

Severity Guidelines

• HIGH: Conversion bypassing security checks
• MEDIUM: Conversion causing logic errors
• LOW: Minor conversion issues

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