-1' OR 5*5=25 --

Short answer: it looks like a classic SQL injection payload.

What it does (high level):

• -1' tries to terminate a string literal in a SQL query.
• OR introduces an alternate condition.
• 5*5=25 is a tautology (true), so that condition evaluates to true.
• -- starts a comment, so the rest of the original query is ignored.

In a vulnerable login query like: SELECT * FROM users WHERE username = '\(username' AND password = '\)password'; If $username is -1' OR 55=25 --, the query becomes effectively: SELECT * FROM users WHERE username = '-1' OR 55=25 --' AND password = '$password'; The WHERE clause becomes true, potentially bypassing checks.

Defensive measures (how to prevent this in code):

• Use parameterized queries / prepared statements (do not interpolate user input directly).
  • Example patterns:
    • Python (sqlite3/psycopg2): cur.execute("SELECT * FROM users WHERE username = ? AND password = ?", (username, password))
    • Java (JDBC): PreparedStatement ps = conn.prepareStatement("SELECT * FROM users WHERE username = ? AND password = ?"); ps.setString(1, username); ps.setString(2, password);
    • Node.js (mysql2): connection.execute("SELECT * FROM users WHERE username = ? AND password = ?", [username, password])
• Validate and sanitize inputs where appropriate, but rely on parameterization for security.
• Use least-privilege database accounts and avoid “admin” rights for application DB users.
• Disable multiple statements in the DB connection (where possible) and use input validation and escaping as a supplementary defense.
• Consider a Web Application Firewall (WAF) and logging/monitoring for anomalous input patterns.

If you want, I can tailor a short, exam-ready note or show concrete code snippets in your preferred language. Which language would you like?