SYNful Knock

December 21, 2023 ยท View on GitHub

ID X0020
Type Backdoor
Aliases None
Platforms Cisco
Year 2015
Associated ATT&CK Software None

SYNful Knock

SYNful Knock is a modification of the router's firmware images used to maintain persistence. [1]

Enhanced ATT&CK Techniques

NameUse
Persistence::Component Firmware::Router Firmware (F0009.001)SYNful Knock is a stealthy modification of the router's firmware image that can be used to maintain persistence within a victim's network. [1]
Defense Evasion::Hijack Execution Flow (F0015)SYNful Knock hooks iOS functions to call and initialize the malware. [1]

MBC Behaviors

NameUse
Memory::Change Memory Protection (C0008)SYNful Knock modifies the translation lookaside buffer (TLB) Read/Write attributes. [1]
Communication::Socket Communication::Send TCP Data (C0001.014)To initiate communication with the C2 server, a uniquely crafted TCP SYN packet is sent to port 80 of the "implanted" router. [1]
Defense Evasion::Alternative Installation Location::Fileless Malware (B0027.001)100 memory-resident modules can be installed. [1]

References

[1] https://www.mandiant.com/resources/synful-knock-acis