-1" OR 5*5=26 --

This looks like a classic SQL injection payload. Here’s a quick breakdown and what it means in exam-style terms:

• -1"

  • Tries to terminate a string literal that an application might have inserted into a SQL statement. The idea is to break out of the string context.

• OR 5*5=26

  • Adds a new condition to the WHERE clause. Since 55 equals 25, the expression 55=26 is false. The intent is to alter the logic of the query.

• Starts a SQL comment. Everything after -- is ignored by the SQL parser, which helps hide the rest of the original query.

Overall purpose (in a typical vulnerable app): to alter the SQL logic so that the query returns more data or bypasses parts of the intended checks (e.g., a login check). In practice, whether this actually works depends on how the app builds and executes SQL.

Important notes:

• In modern apps that use parameterized queries or prepared statements, such injections are much less likely to succeed because user input is treated strictly as data, not as part of the SQL code.
• The exact effect can vary by database system and by how the input is embedded into the query.

How to defend (exam/real-world guidance):

• Use parameterized queries (prepared statements) for all user input.
• Avoid constructing SQL by concatenating strings with user input.
• Apply input validation and escaping only as a supplementary defense, not as the primary guard.
• Use least-privilege database accounts (no rights to execute arbitrary statements).
• Disable multi-statement execution if your DB driver supports it.
• Consider using ORM or stored procedures with strict parameters.

If you want, I can show a simple before/after example of a vulnerable pattern and how to fix it with prepared statements, or discuss how this pattern would be treated in SQL dialects you’re studying. Do you want a quick walkthrough with a concrete example?