: A function used to query XML data. If given an invalid path (which this payload provides), it throws a database error.
What is SQL Injection? Tutorial & Examples | Web Security Academy
: Calculates the MD5 hash of a specific number. In security testing, this is used as a "canary"—if the database error message displays the calculated hash, the tester knows the injection was successful. : A function used to query XML data
: char(126) is the tilde character ( ~ ). The payload attaches this to the start of the data so that the resulting error message clearly displays the extracted value.
The string you've provided is an example of a used in automated vulnerability scanning or attacks. It is not a legitimate "proper feature" of a software application; rather, it is designed to exploit security flaws in a database's error-handling mechanism. Breakdown of the Payload Tutorial & Examples | Web Security Academy :
This specific payload uses an technique targeting MySQL or MariaDB databases.
: Appends a logical condition. The /**/ is a comment used to bypass simple security filters that block spaces. extractvalue(1, concat(char(126), md5(1002059835))) : The payload attaches this to the start of
: Attempts to balance the trailing single quote of the original query to prevent a syntax error that might stop the script from running. Context of Use