defection.io

malware

SYNful Knock S0519

Type: malware
Platform: Network Devices
Created: 19 October 2020
Last modified: 15 April 2025

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]

TechniquesBottom 12%

Tactics41st pct

Threat groupsNone recorded

CampaignsNone recorded

Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.

defection.io

malware

SYNful Knock S0519

Type: malware
Platform: Network Devices
Created: 19 October 2020
Last modified: 15 April 2025

TechniquesBottom 12%

Tactics41st pct

Threat groupsNone recorded

CampaignsNone recorded

Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.

SYNful Knock MITRE reference S0519

Traffic Signaling T1205 ↗

SYNful Knock can be sent instructions via special packets to change its functionality. Code for new functionality can be included in these messages.3

Persistence · Stealth · Command and Controlno detection rules

Network Device Authentication T1556.004 ↗

SYNful Knock has the capability to add its own custom backdoor password when it modifies the operating system of the affected network device.4

Persistence · Defense Impairment · Credential Access2 detection rules

Patch System Image T1601.001 ↗

SYNful Knock is malware that is inserted into a network device by patching the operating system image.5 6

Defense Impairment1 detection rules

Standing S0519

Reach is how much of ATT&CK this malware touches. Coverage is how well defended each thing it does is, as a median per technique rather than a total — a total would just restate the reach. Each figure is ranked against all 825 ATT&CK software entries only where that population actually spreads. Where most of the population shares one value, a percentile would rank the tie instead of the entity, so the raw value is shown and no rank is claimed.

Reach

Techniques3Bottom 12%

12th percentile · 88% of 825 ATT&CK software entries have more Enterprise techniques.

Tactics541st pct

41st percentile · 59% of 825 ATT&CK software entries have more tactics spanned.

Threat groups061% tie · 22 values

61% of the population shares a single value across only 22 distinct values, so a percentile here would rank the tie, not the entity.

Campaigns085% tie · 8 values

85% of the population shares a single value across only 8 distinct values, so a percentile here would rank the tie, not the entity.

Coverage

Rules / technique1medBottom 1%

1st percentile · 99% of 825 ATT&CK software entries have more detection rules per technique.

Tests / technique0medBottom 2%

2nd percentile · 98% of 825 ATT&CK software entries have more atomic tests per technique.

Data comps / technique3med54% tie · 11 values

54% of the population shares a single value across only 11 distinct values, so a percentile here would rank the tie, not the entity.

Mitigations / technique2medTop 9%

91st percentile · 91% of 825 ATT&CK software entries have this many mitigations per technique or fewer.

5 of 8 axes carry an honest rank on this page. Coverage medians are taken across this malware’s 3 Enterprise techniques.

Range

Technique Campaign use over its cumulative rule count.

Campaigns · 0Sigma rules (cumulative) · 1Splunk ESCU (cumulative) · 2