"SYNful Knock" is a form of malware that specifically targets Cisco devices running the Cisco IOS. First identified in 2015, it functions by installing an implant within the targeted device, creating a persistent access point that is challenging to detect. This malware represents one of seven known incidents over the past four years where Cisco IOS devices have been the focus of malicious attacks. The stealthy nature of SYNful Knock involves modifying the router's firmware image, a tactic used to maintain persistence within the victim's network.
The operation of SYNful Knock is characterized by static modifications to the Cisco IOS binary, mirroring tactics seen in previous incidents. Despite its sophisticated design, SYNful Knock, like malware instances #0, #1, #2, and #3, cannot withstand the installation of a verified good Cisco IOS binary image sourced from a trusted entity. Ensuring the correct hash values can effectively neutralize the threat posed by this malware.
In response to the emergence and subsequent detection of SYNful Knock, practical methods and tools for identifying a compromise have been developed and shared publicly. Notably, SNORT and Yara signatures have been released to aid in detecting the presence of this specific malware. These proactive measures aim to bolster defenses against SYNful Knock, helping to secure Cisco IOS devices from further exploitation.
Description last updated: 2024-05-04T23:29:17.020Z