-1" OR 5*5=25 or "vyHjdoKB"="

What you posted looks like a classic SQL injection payload fragment. It tries to manipulate a query so that the WHERE clause evaluates to true regardless of the actual input.

Key idea:

• The part -1" seems to terminate a previous string literal in the SQL query.
• OR 5*5=25 is a tautology (always true). If this gets inserted into a WHERE clause, it can make the entire condition true, potentially bypassing authentication or returning more rows than intended.
• The rest ("vyHjdoKB"=") is another fragment that might be intended to extend the condition, but on its own it’s incomplete. The important bit is the OR 5*5=25 making the condition true.

In exam terms, this demonstrates:

• Why unsafely concatenating user input into SQL is dangerous.
• How boolean expressions can be used to bypass checks.

Safe defenses (how to fix in practice):

• Use parameterized queries/prepared statements rather than string concatenation.
  • Vulnerable (conceptual): SELECT * FROM users WHERE username = 'USER_INPUT' AND password = 'PASSWORD';
  • Secure: SELECT * FROM users WHERE username = ? AND password = ?; with parameters bound safely.
• Validate and constrain all input (allowlists, length checks).
• Use least-privilege database accounts (no rights to write/drop tables if not needed).
• Disable detailed error messages that reveal query structure.
• Consider using ORM or stored procedures with bound parameters.
• Regularly test for injection with safe, legal security testing in a controlled lab.

If you want, I can show a concise side-by-side example (vulnerable vs. secure) in a language you’re studying (e.g., Python with psycopg2, Java with JDBC, etc.).