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Elastic Docs ›SIEM Guide [7.8] ›Detections (beta) ›Prebuilt rule reference

Unusual DNS Activity

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Unusual DNS Activity

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A machine learning job detected a rare and unusual DNS query that indicates network activity with unusual DNS domains. This can be due to initial access, persistence, command-and-control, or exfiltration activity. For example, when a user clicks on a link in a phishing email or opens a malicious document, a request may be sent to download and run a payload from an uncommon domain. When malware is already running, it may send requests to an uncommon DNS domain the malware uses for command-and-control communication.

Rule type: machine_learning

Machine learning job: packetbeat_rare_dns_question

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
  • Packetbeat

Version: 1

Added (Elastic Stack release): 7.7.0

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 signal. Network activity that occurs rarely, in small quantities, can trigger this signal. Possible examples are browsing technical support or vendor networks sparsely. A user who visits a new or unique web destination may trigger this signal.

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