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Elastic Docs ›Elastic Security Solution [8.5] ›Detections and alerts ›Prebuilt rule reference
« Conhost Spawned By Suspicious Parent Process Connection to Commonly Abused Web Services »

Connection to Commonly Abused Free SSL Certificate Providersedit

Identifies unusual processes connecting to domains using known free SSL certificates. Adversaries may employ a known encryption algorithm to conceal command and control traffic.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Command and Control

Version: 100 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guideedit












Rule queryedit








network where network.protocol == "dns" and /* Add new free SSL
certificate provider domains here */ dns.question.name :
("*letsencrypt.org", "*.sslforfree.com", "*.zerossl.com",
"*.freessl.org") and /* Native Windows process paths that are
unlikely to have network connections to domains secured using free SSL
certificates */ process.executable :
("C:\\Windows\\System32\\*.exe",
"C:\\Windows\\System\\*.exe",
"C:\\Windows\\SysWOW64\\*.exe",
"C:\\Windows\\Microsoft.NET\\Framework*\\*.exe",
"C:\\Windows\\explorer.exe",
"C:\\Windows\\notepad.exe") and /* Insert noisy false positives
here */ not process.name : ("svchost.exe", "MicrosoftEdge*.exe",
"msedge.exe")











Threat mappingedit




Framework: MITRE ATT&CKTM














Rule version historyedit










Version 100 (8.5.0 release)








    

  • 
Formatting only

    • 









Version 6 (8.4.0 release)








    

  • 

    Updated query, changed from:
    

    

    

    network where network.protocol == "dns" and /* Add new free SSL
certificate provider domains here */ dns.question.name :
("*letsencrypt.org", "*.sslforfree.com", "*.zerossl.com",
"*.freessl.org") and /* Native Windows process paths that are
unlikely to have network connections to domains secured using free SSL
certificates */ process.executable :
("C:\\Windows\\System32\\*.exe",
"C:\\Windows\\System\\*.exe",
"C:\\Windows\\SysWOW64\\*.exe",
"C:\\Windows\\Microsoft.NET\\Framework*\\*.exe",
"C:\\Windows\\explorer.exe",
"C:\\Windows\\notepad.exe") and /* Insert noisy false positives
here */ not process.name : ("svchost.exe", "MicrosoftEdge*.exe",
"msedge.exe")
    

    

    • 









Version 4 (8.2.0 release)








    

  • 
Formatting only

    • 









Version 3 (7.12.0 release)








    

  • 
Formatting only

    • 









Version 2 (7.11.2 release)








    

  • 
Formatting only

    • 


















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