This indicates an attack attempt to exploit a Format String vulnerability in IBM Tivoli Storage Manager FastBack Server.
The vulnerability is caused by an improper validation of user supplied data when the vulnerable application handles a maliciously crafted request. An attacker can exploit this to execute arbitrary code in the context of the vulnerable application via a crafted request.
IBM Tivoli Storage Manager FastBack prior to 6.1.12
System Compromise: Remote attackers can gain control of vulnerable systems
Apply the most recent upgrade or patch from the vendor