This indicates an attack attempt to exploit a Command Injection vulnerability in D-Link DIR series router.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling a crafted HTTP request. An unauthenticated remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted HTTP request.
D-Link DIR-859 with Firmware version 1.06b01 Beta01 and prior
System Compromise: Remote attackers can execute arbitrary code on vulnerable systems.
Apply the most recent upgrade or patch from the vendor.