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Elastic Docs ›Elastic Security Solution [7.11] ›Detections and Alerts ›Prebuilt rule reference

Unusual Linux Network Activity

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Unusual Linux Network Activity

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Identifies Linux processes that do not usually use the network but have unexpected network activity, which can indicate command-and-control, lateral movement, persistence, or data exfiltration activity. A process with unusual network activity can denote process exploitation or injection, where the process is used to run persistence mechanisms that allow a malicious actor remote access or control of the host, data exfiltration, and execution of unauthorized network applications.

Rule type: machine_learning

Machine learning job: linux_anomalous_network_activity_ecs

Machine learning anomaly threshold: 50

Severity: low

Risk score: 21

Runs every: 15 minutes

Searches indices from: now-45m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Linux
  • Threat Detection
  • ML

Version: 3 (version history)

Added (Elastic Stack release): 7.7.0

Last modified (Elastic Stack release): 7.10.0

Rule authors: Elastic

Rule license: Elastic License

Investigation guide

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Alerts from this rule indicate the presence of network activity from a Linux process for which network activity is rare and unusual. Here are some possible avenues of investigation:

  • Consider the IP addresses and ports. Are these used by normal but infrequent network workflows? Are they expected or unexpected?

  • If the destination IP address is remote or external, does it associate with an expected domain, organization or geography?

    Avoid interacting directly with suspected malicious IP addresses.

  • Consider the user as identified by the username field. Is this network activity part of an expected workflow for the user who ran the program?
  • Examine the history of execution. If this process manifested only very recently, it might be part of a new software package. If it has a consistent schedule - for example if it runs monthly or quarterly - it might be part of a monthly or quarterly business or maintenance process.
  • Examine the process arguments, title and working directory. These may provide indications as to the source of the program or the nature of the tasks it is performing.

Rule version history

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Version 3 (7.10.0 release)
  • Formatting only
Version 2 (7.9.0 release)
  • Formatting only
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