This indicates an attack attempt against a buffer-overflow vulnerability in Free Download Manager.
The vulnerability is caused by a boundary error when the vulnerable software handles a malicious ".torrent" file. It allows a remote attacker to execute arbitrary code.
Free Download Manager (FDM) 2.5 Build 758 and 3.0 Build 844
System Compromise: Remote attackers can gain control of vulnerable systems.
Upgrade to the latest version 3.0 build 848.