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: 5m
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References: None
Tags:
- 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 */
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")
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
-
Technique:
- Name: Encrypted Channel
- ID: T1573
- Reference URL: https://attack.mitre.org/techniques/T1573/