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Protocol or Port Mismatch

The following analytic identifies network traffic where the higher layer protocol does not match the expected port, such as non-HTTP traffic on TCP port 80. It leverages data from network traffic inspection…

Description

The following analytic identifies network traffic where the higher layer protocol does not match the expected port, such as non-HTTP traffic on TCP port 80. It leverages data from network traffic inspection technologies like Bro or Palo Alto Networks firewalls. This activity is significant because it may indicate attempts to bypass firewall restrictions or conceal malicious communications. If confirmed malicious, this behavior could allow attackers to evade detection, maintain persistence, or exfiltrate data through commonly allowed ports, posing a significant threat to network security.

Detection logic

Detection requirements

Platform
ESXiLinuxmacOSNetwork DevicesWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

  • Some false positive could occur with some applications that change their default communication port for an added layer of obscurity.

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