-1' OR 3*2<5 or 'RLFgWRKv'='

It looks like a fragment of an SQL injection attempt. It’s trying to close a string literal and inject extra OR conditions into a SQL statement.

What the pieces do (in short) -3*2<5 evaluates to false, since 6 is not less than 5. -'RLFgWRKv'='' would also be false (a nonempty string is not equal to the empty string).

• -1' at the start is an attempt to break out of a quoted string in a vulnerable query.

If this were inserted into something like ... WHERE username = '$input' it could turn into ... WHERE username = '-1' OR 3*2<5 OR 'RLFgWRKv'='' which effectively becomes ... WHERE username = '-1' OR FALSE OR FALSE so the injected parts don’t actually make the condition true; the overall effect reduces to username = '-1' (assuming the parser handles the injection as shown). The final '=' with nothing after it also makes the payload incomplete and would typically cause a syntax error.

Important defensive note

• This is the kind of payload attackers try to use to bypass login or manipulate queries. It should be treated as a cautionary example of why you must not concatenate user input into SQL.
• Prevent via:
  • Use parameterized queries / prepared statements (e.g., SELECT ... WHERE username = ? or %s with bound parameters).
  • Validate and sanitize inputs, and apply least-privilege database accounts.
  • Consider using an ORM and/or input escaping where appropriate.
  • Implement input/output encoding and consider a web app firewall for defense-in-depth.

If you’re studying for an exam, I can tailor a quick practice question:

• Given a vulnerable query like: SELECT * FROM users WHERE username = '\(input' AND password = '\)password'; a) Why is this vulnerable? b) What would a safe parameterized version look like? c) How would you test for SQL injection safely in a lab environment?

Would you like me to expand on any of these points or provide a short, exam-style problem with solutions?