SYNful Knock can be sent instructions via special packets to change its functionality. Code for new functionality can be included in these messages.3
tool
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]
3
TechniquesBottom 12%
5
Tactics41st pct
0
Threat groupsNone recorded
0
CampaignsNone recorded
Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.
MITRE reference S0519
SYNful Knock has the capability to add its own custom backdoor password when it modifies the operating system of the affected network device.4
SYNful Knock is malware that is inserted into a network device by patching the operating system image.56
Standing S0519
Reach is how much of ATT&CK this tool 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 / technique0med
Detection coverage S0519
3 distinct rules cover the 3 techniques recorded for this tool. 2 Splunk · 1 Sigma.
2 covered by at least one rule1 with no coverage3 distinct rules in total
tf
Loading...Drag headers to reorder | Drag edges to resize
tf
Loading detections...
| Select | Title | Description | Category | Status | Event | Product | MITRE ATT&CK | CVEs | Severity | Author | Created | Updated | ID | Refs |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
© 2026 The MITRE Corporation. ATT&CK® and D3FEND™ data reproduced with permission. SigmaHQ detection rules licensed under DRL 1.1. attack.mitre.org · d3fend.mitre.org · CAR analytics licensed under Apache 2.0 · car.mitre.org