S0519: SYNful Knock
SYNful Knock 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.[1][2]
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SYNful Knock
SYNful Knock 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.[1][2]
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
Techniques used
This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.
| Domain | ID | Name | Relationship / procedure |
|---|---|---|---|
| Enterprise | T1601.001 | Patch System ImageSub-technique | SYNful Knock is malware that is inserted into a network device by patching the operating system image.[1][2] |
| Enterprise | T1205 | Traffic Signaling | SYNful Knock can be sent instructions via special packets to change its functionality. Code for new functionality can be included in these messages.[1] |
| Enterprise | T1556.004 | Network Device AuthenticationSub-technique | SYNful Knock has the capability to add its own custom backdoor password when it modifies the operating system of the affected network device.[1] |
All related ATT&CK context
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates.
Imported snapshots across ATT&CK releases(3)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 20.0 | 1.1 | Current bundle | 3510599abaf5… | ||
| 19.2 | 1.1 | Older bundle | 3510599abaf5… | ||
| 19.1 | 1.1 | Older bundle | 3510599abaf5… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
- [1]Mandiant - Synful Knock
Bill Hau, Tony Lee, Josh Homan. (2015, September 15). SYNful Knock - A Cisco router implant - Part I. Retrieved November 17, 2024.
Open source URL - [2]Cisco Synful Knock Evolution
Graham Holmes. (2015, October 8). Evolution of attacks on Cisco IOS devices. Retrieved October 19, 2020.
Open source URL - [3]mitre-attackS0519Open source URL
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