Labs / Regex Bypass to SQLi
- Challenge
- Released 27 Oct 2025
🎯 One character. One flag. Can you exploit the regex?
A corporate directory validates user input with a regex pattern and Python's re.MULTILINE flag. The developers are confident their ^[a-z0-9 ]+$ pattern blocks all SQL injection attempts. They don't realize that MULTILINE changes how ^ and $ anchors behave. Security researchers know that a single control character can split validation logic across lines, bypassing even careful regex checks. Exploit this documented vulnerability and demonstrate why regex patterns cannot secure SQL queries.
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Web Security: Regex Bypass Leading to SQL Injection
This challenge demonstrates how flawed regex-based input validation fails to prevent SQL injection attacks. Developers often use regex patterns to block dangerous keywords, but case sensitivity and incomplete validation allow bypasses.
What You'll Learn
- Bypassing regex-based SQLi filters
- Case-sensitive keyword filtering flaws
- UNION-based SQL injection techniques
- SQLite injection exploitation
Challenge Overview
A corporate user directory implements regex filtering to prevent SQL injection. The filter blocks semicolons and backslashes, plus uppercase SQL keywords, but can be bypassed using lowercase syntax to extract the flag from the database.