H3XAOperational intelligence
Live analytical pictureEvidence before assessment
Threat intelligence / Malware

SYNful Knock

[SYNful Knock](https://attack.mitre.org/software/S0519) is a stealthy modification of the operating system of network devices that can be used to maintain persistence within a victim's network and provide new capabilities to the adversary.(Citation: Mandiant - Synful Knock)(Citation: Cisco Synful Knock Evolution)

Malware
TypeMalware
External ID—
First seen2026-08-14
Last seen2026-08-14

Confidence

—

[SYNful Knock](https://attack.mitre.org/software/S0519) is a stealthy modification of the operating system of network devices that can be used to maintain persistence within a victim's network and provide new capabilities to the adversary.(Citation: Mandiant - Synful Knock)(Citation: Cisco Synful Knock Evolution)

Labels

malware
3 recorded

Relationships

uses
to Network Device Authentication
Technique
uses
to Patch System Image
Technique
uses
to Traffic Signaling
Technique
3 external

References

mitre-attack
S0519
open
Mandiant - Synful Knock
https://cloud.google.com/blog/topics/threat-intelligence/synful-knock-acis/
open
Cisco Synful Knock Evolution
https://blogs.cisco.com/security/evolution-of-attacks-on-cisco-ios-devices
open
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