-4640 Union All Select Null,null,null,null,'qbqvq'||'lbznmmwdachxaypteqetdoupxsqdsedwqcwkldne'||'qqbqq',null,null,null,null-- Exgp -

If this string was found in your server logs or application inputs, it indicates that an was performed against your system. It is a signature of a tool checking if it can "reflect" data back to itself through your database.

: The payload concatenates (using || ) three strings. Canary Strings : qbqvq and qqbqq are "canaries" or markers. If this string was found in your server

Are you seeing this in your or during a security audit ? If this string was found in your server