-1' OR 5*5=25 or '8g9pTWkb'='

What you’ve written is a classic-looking SQL injection payload.

Overview

• The snippet tries to close a string literal in a SQL query and then inject an always-true condition.
• 5*5=25 is a tautology (always true). Using OR with a true condition can make the WHERE clause evaluate to true, potentially bypassing checks like authentication.
• The part around '8g9pTWkb'=' is another attempt to create a condition, though as written it’s incomplete. The general idea is to chain OR conditions so the query returns results regardless of the actual input.

Why this works (in a typical vulnerable setup)

• If a query is built by concatenating user input, e.g.: SELECT * FROM users WHERE username = '' AND password = '';
• An attacker can supply something like -1' OR 5*5=25 OR 'a'=' to turn the WHERE clause into something that’s always true (the exact syntax may vary by DB and how the input is embedded).
• Result: a login bypass or retrieval of data the attacker shouldn’t have access to.

Defensive measures (how to prevent this)

• Use parameterized queries / prepared statements. Never embed user input directly into SQL strings.
  • Example (conceptual):
    • SELECT * FROM users WHERE username = ? AND password = ?
    • Bind username and password as separate parameters.
• Use proper input handling and validation, but don’t rely on escaping alone. Escaping can be error-prone.
• Apply least privilege on the database account used by the application (e.g., no DROP/ALTER rights from the app user; only read/write as needed).
• Use modern ORMs or database access layers that automatically parameterize queries.
• Disable detailed error messages that reveal SQL syntax or structure to end users.
• Implement input whitelisting for fields (e.g., restrict username to allowed characters/length, enforce password policies on the client/server).
• Consider a Web Application Firewall (WAF) and regular security testing (code reviews, static analysis, and controlled penetration testing).

If you’re studying for an exam, you can mention:

• This is a demonstration of why dynamic SQL with user input is dangerous.
• The recommended fix is parameterized queries and proper access controls.
• You can also contrast with safe alternatives like using stored procedures with bound parameters or ORM-provided query builders.

If you want, I can show a safe, concrete example in a language you’re studying (Python + sqlite/postgres, or Java with JDBC) to illustrate how parameter binding prevents this kind of injection.