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

That looks like a classic (but unsafe) SQL injection payload. It’s designed to tamper with a query by injecting a condition that could evaluate to true, potentially bypassing authentication or altering the query logic.

What the pieces suggest, in general (not a full exploit guide):

• -1' : This is trying to close an existing quoted string in the SQL statement (the trailing quote ends the user-supplied value).
• OR 55=25 : 55=25 is a tautology (true). If the surrounding query is something like WHERE user = 'X' AND password = 'Y', injecting OR 5*5=25 can turn the WHERE clause into something that evaluates to true for all rows.
• or '8g9pTWkb'='' : This is another attempt to keep the syntax valid after breaking out of the string; the exact trailing=' part here is incomplete, but the intent is to produce a valid-looking clause that still yields true in the WHERE condition.

Important safety notes:

• Do not test or use such payloads on systems you don’t own or have explicit permission to test.
• This highlights why raw string concatenation with user input is dangerous.

Defensive practices (how to defend against this in real apps):

• Use parameterized queries / prepared statements. Do not concatenate user input into SQL queries.
  • Example (conceptual): SELECT id FROM users WHERE username = ? AND password_hash = ?
• Use proper password handling: store salted hashes (e.g., bcrypt, Argon2) and compare hashes, not plaintext.
• Validate and constrain input (type, length, allowed characters) but rely on parameterization for correctness and security.
• Use least-privilege database accounts (the app should not own data beyond what it needs).
• Enable robust error handling to avoid leaking SQL error details to users.
• Consider using ORM layers or stored procedures with bound parameters.
• Employ Web Application Firewall (WAF) with input monitoring as a defense-in-depth measure.

If you’d like, I can:

• Provide a short exam-style answer outlining the vulnerability and mitigation.
• Show a safe, concrete example of how to rewrite a insecure query using parameterized statements in a language you’re studying (e.g., Python with psycopg2, Java with PreparedStatement, etc.).