CHR(100)||CHR(85)||CHR(102)||CHR(83) translates to the string "dUfS" .The code asks the database: "Does dUfS equal dUfS?" Since this is always true, the database will process the request without an error.
This is a final "always true" statement used to ensure the rest of the original, legitimate SQL query doesn't break the injection. What is the Goal? The reference to SYSIBM
The reference to SYSIBM.SYSDUMMY1 is a dead giveaway that the target is an IBM DB2 database. This is a special "one-row, one-column" table used to perform calculations or retrieve system values. Anatomy of the Payload If the page loads,
This string is a classic example of a payload, specifically designed to test for vulnerabilities in a database—in this case, IBM DB2 . Anatomy of the Payload IBM DB2 .
If the page loads, the answer is "Yes." If it fails, the answer is "No." By repeating this, they can extract entire databases character by character. How to Prevent This