IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
Connection to Commonly Abused Free SSL Certificate Providers
editConnection to Commonly Abused Free SSL Certificate Providers
editIdentifies 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 guide
editRule query
editnetwork 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/