Only allow the types of characters you expect (e.g., numbers for an ID field).
A system table in Access that contains information about database objects. If successful, the attacker can see if they have access to system metadata [1, 4].
The best way to stop these attacks is to never "glue" user input directly into your database queries. Instead, use: Only allow the types of characters you expect (e
These can often detect and block common patterns like UNION ALL SELECT before they reach your server.
Are you working on or just curious about how these injection patterns work? The best way to stop these attacks is
If you are looking to learn about this for security research or to protect your own applications, here is a quick guide on what’s happening and how to prevent it. What this payload does:
Matches the number of columns in the original table. Attackers use NULL to figure out how many columns they need to match without causing a data type error [2, 3]. If you are looking to learn about this
Comments out the rest of the original query so it doesn't cause a syntax error [1, 5]. How to Prevent It: