Anomalous Process For a Windows Populationedit

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 signals per execution: 100

References:

Tags:

  • Elastic
  • ML
  • Windows

Version: 1

Added (Elastic Stack release): 7.7.0

Potential false positivesedit

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

Investigation guideedit

Signals 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.