While this appears safe to a novice developer, it neglects a foundational rule of parsing logic: The Character Collision
The application uses the following SQL query to search for users:
A WAF can help detect and block SQL injection attempts, but it should be considered a complementary control, not a replacement for secure coding practices. Sql Injection Challenge 5 Security Shepherd
The system attempts to block single quotes ( ' ) by applying an automated find-and-replace filter.
sqlmap -u "http:// /challengeURL" --cookie="JSESSIONID= " --data="vulnerable_param=1" --dbms=MySQL --level=5 --risk=3 --technique=T --dump Use code with caution. While this appears safe to a novice developer,
When this payload is processed by the flawed sanitization filter, the application alters the structural context of the query string:
Mastering SQL Injection Challenge 5 in OWASP Security Shepherd When this payload is processed by the flawed
This is where the subtlety of the challenge lies. If a user attempts a classic SQL injection attack, such as typing 1' OR 1=1; -- , the single quote will be escaped. The query effectively becomes 1\' OR 1=1; -- , which may not execute as intended or could cause an SQL error, as the escaped quote is treated as a literal character rather than a string delimiter.
The login logic likely follows a pattern (pseudocode):
The resulting string processed by the database engine becomes \\' .
In Challenge 5, the filter blocks SELECT regardless of case. So we need another way to read data.