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Anomalous Process For a Windows Population

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Anomalous Process For a Windows Population

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Searches for rare processes running on multiple hosts in an entire fleet or network. This reduces the detection of false positives since automated maintenance processes usually only run occasionally on a single machine but are common to all or many hosts in a fleet.

Rule type: machine_learning

Machine learning job: windows_anomalous_process_all_hosts_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
  • Windows
  • 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

Potential false positives

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A newly installed program or one that runs rarely as part of a monthly or quarterly workflow could trigger this alert.

Investigation guide

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Alerts from this rule indicate the presence of a Windows process that is rare and unusual for all of the Windows hosts for which Winlogbeat data is available. Here are some possible avenues of investigation:

  • Consider the user as identified by the username field. Is this program part of an expected workflow for the user who ran this program on this host?
  • 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 process.
  • Examine the process metadata like the values of the Company, Description and Product fields, which may indicate whether the program is associated with an expected software vendor or package.
  • Examine arguments and working directory. These may provide indications as to the source of the program or the nature of the tasks it is performing.
  • Consider the same for the parent process. If the parent process is a legitimate system utility or service, this could be related to software updates or system management. If the parent process is something user-facing like an Office application, this process could be more suspicious.
  • If you have file hash values in the event data, and you suspect malware, you can optionally run a search for the file hash to see if the file is identified as malware by anti-malware tools.

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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