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-windows.*

Severity: low

Risk score: 21

Runs every: 5m

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

Maximum alerts per execution: 100

References: None


  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Command and Control
  • Data Source: Elastic Defend

Version: 104

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guideedit

Rule queryedit

network where host.os.type == "windows" and network.protocol == "dns" and
  /* Add new free SSL certificate provider domains here */ : ("*", "*", "*", "*") 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\\notepad.exe") and

  /* Insert noisy false positives here */
  not : ("svchost.exe", "MicrosoftEdge*.exe", "msedge.exe")