This indicates an attack attempt against a Stack Buffer Overflow vulnerability in D-Link DIR-645.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling a crafted HTTP request. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted request to the vulnerable service.
D-Link DIR-645 1.03B08 and prior version
System Compromise: Remote attackers can execute arbitrary code in the context of the affected application.
Apply the most recent upgrade or patch from the vendor.