Elastic Security Detection Rules

SMTP on Port 26/TCP

Last updated a year ago on 2025-01-15
Created 6 years ago on 2020-02-18

About

This rule detects events that may indicate use of SMTP on TCP port 26. This port is commonly used by several popular mail transfer agents to deconflict with the default SMTP port 25. This port has also been used by a malware family called BadPatch for command and control of Windows systems.
Tags
Tactic: Command and ControlDomain: EndpointUse Case: Threat DetectionData Source: PAN-OSLanguage: kuery
Severity
low
Risk Score
21
MITRE ATT&CK™

Command and Control (TA0011)(external, opens in a new tab or window)

Exfiltration (TA0010)(external, opens in a new tab or window)

↳ Exfiltration Over Alternative Protocol (T1048)(external, opens in a new tab or window)

False Positive Examples
Servers that process email traffic may cause false positives and should be excluded from this rule as this is expected behavior.
License
Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type
Query (Kibana Query Language)
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
packetbeat-*auditbeat-*filebeat-*logs-network_traffic.*logs-panw.panos*
Related Integrations

network_traffic(external, opens in a new tab or window)

panw(external, opens in a new tab or window)

Query
text code block:
(event.dataset: (network_traffic.flow or zeek.smtp) or event.category:(network or network_traffic)) and network.transport:tcp and destination.port:26

Install detection rules in Elastic Security

Detect SMTP on Port 26/TCP in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).