BPF filter applied using TC

Elastic Stack Serverless Security

Detects when the tc (transmission control) binary is utilized to set a BPF (Berkeley Packet Filter) on a network interface. Tc is used to configure Traffic Control in the Linux kernel. It can shape, schedule, police and drop traffic. A threat actor can utilize tc to set a bpf filter on an interface for the purpose of manipulating the incoming traffic. This technique is not at all common and should indicate abnormal, suspicious or malicious activity.

Rule type: eql

Rule indices:

• logs-endpoint.events.*
• endgame-*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References:

• https://github.com/h3xduck/TripleCross/blob/master/src/helpers/deployer.sh
• https://man7.org/linux/man-pages/man8/tc.8.html

Tags:

• Elastic
• Host
• Linux
• Threat Detection
• Execution
• TripleCross
• Elastic Endgame

Version: 102

Rule authors:

• Elastic

Rule license: Elastic License v2

process where event.type != "end" and process.executable : "/usr/sbin/tc" and process.args : "filter" and process.args : "add" and process.args : "bpf" and not process.parent.executable: "/usr/sbin/libvirtd"

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Execution
  • ID: TA0002
  • Reference URL: https://attack.mitre.org/tactics/TA0002/

• Technique:

  • Name: Command and Scripting Interpreter
  • ID: T1059
  • Reference URL: https://attack.mitre.org/techniques/T1059/

• Sub-technique:

  • Name: Unix Shell
  • ID: T1059.004
  • Reference URL: https://attack.mitre.org/techniques/T1059/004/