If you are a developer, seeing this in your logs means someone is scanning your site for holes. You can stop these attacks by using (Prepared Statements). This ensures the database treats input as "just text" rather than executable code, rendering the single quotes and CHR commands harmless.
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. If you are a developer, seeing this in
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. The reference to SYSIBM
If the website loads normally, the attacker knows the database processed the "True" statement ( dUfS = dUfS ) successfully. If the website loads normally, the attacker knows
This specific payload is likely a test.
The payload uses AND statements. For the database to return a result, the conditions following the AND must be true.