Authentication Bypass Patterns
Overview
Authentication bypasses exploit logical flaws:
- PHP type juggling:
"0e1234..." == "0e5678..."(magic hash) - SQL truncation: Long username overflows DB field to match existing user
- NULL password bypass: Some DBs accept NULL as matching any hash
- Mass assignment bypass: Posting
isAdmin: truewith registration data
Remediation
- Use strict comparison (
===not==in PHP/JS) - Validate input length against database field limits
- Use parameterized queries everywhere
- Never trust user-submitted role or privilege fields