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Elastic Docs ›Elastic Security Solution [8.6] ›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

Rule indices: None

Severity: low

Risk score: 21

Runs every: 15m

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

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Endpoint
  • OS: Linux
  • Use Case: Threat Detection
  • Rule Type: ML
  • Rule Type: Machine Learning

Version: 102

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Unusual Network Activity
Detection 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? Note: 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 only manifested recently, it might be part of a new software package. If it has a consistent cadence (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.
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