Non-Standard Port T1571
Tactic: Command & Control
Adversaries may communicate using a protocol and port pairing that are typically not associated. For example, HTTPS over port 8088 or port 587 as opposed to the traditional port 443. Adversaries may make changes to the standard port used by a protocol to bypass filtering or muddle analysis/parsing of network data.
Events covered
11 catalog events are tagged with this technique by at least one rule.
Authoring guide
These 26 rules share fields, values, and exclusions.
Fields filtered most (41 distinct)
These fields appear most often in rule filters.
Top indicator values (195 distinct)
These values appear most often in rule predicates.
Exclusions (133 distinct)
These values appear most often in top-level exclusions.
Rules under this technique
These vendors publish rules tagged with this technique.
Sigma 5 rules
- Communication To Uncommon Destination Ports
- Potentially Suspicious Malware Callback Communication
- Potentially Suspicious Malware Callback Communication - Linux
- Suspicious DNS Z Flag Bit Set
- Testing Usage of Uncommonly Used Port
Elastic 6 rules
- Potential Data Exfiltration Activity to an Unusual Destination Port
- Script Interpreter Connection to Non-Standard Port
- SMTP to the Internet on Port 26/TCP
- Suricata and Elastic Defend Network Correlation
- Suspicious Outbound Network Connection via Unsigned Binary
- Unusual Linux Network Port Activity
Splunk 4 rules
- Cisco NVM - Outbound Connection to Suspicious Port
- Cisco Secure Firewall - Communication Over Suspicious Ports
- Cisco Secure Firewall - File Download Over Uncommon Port
- Ollama Abnormal Network Connectivity
Kusto 9 rules
- Abnormal Port to Protocol
- Fortinet - Beacon pattern detected
- GSA - Detect Abnormal Deny Rate for Source to Destination IP
- GSA - Detect Protocol Changes for Destination Ports
- Palo Alto - potential beaconing detected
- Palo Alto - potential beaconing detected
- Potential beaconing activity (ASIM Network Session schema)
- Ubiquiti - Connection to known malicious IP or C2
- Ubiquiti - Possible connection to cryptominning pool