: In many SQL dialects like MySQL, the hash symbol indicates the start of a comment, which "comments out" the rest of the original, legitimate query so it doesn't cause a syntax error. Security Implications
: Ensure the database user account has the bare minimum permissions necessary to function.
: This likely represents a dummy or non-existent ID. By using an ID that doesn't exist, the attacker ensures the first part of the query returns no results, making the "injected" results from the second part more visible. -9718 UNION ALL SELECT 34,34,34,34,34,34,34,34,34,34#
This pattern is often the "reconnaissance" phase of an attack. Once an attacker knows how many columns a table has and which ones are displayed on the screen, they can replace the dummy numbers with commands to extract sensitive data, such as usernames, passwords, or system configurations. How to Prevent These Attacks To protect your applications, developers should:
: This ensures the database treats the input as literal data rather than executable code. : In many SQL dialects like MySQL, the
: This SQL operator combines the result sets of two or more SELECT statements into a single result.
: Filter and sanitize all user-provided data to block unexpected characters like UNION , SELECT , or # . By using an ID that doesn't exist, the
The phrase you provided, -9718 UNION ALL SELECT 34,34,34,34,34,34,34,34,34,34# , is a classic example of , a technique used to probe a database for vulnerabilities. Understanding the Syntax