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.sysmon_operational-*
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
- Data Source: Sysmon
Version: 106
Rule authors:
- Elastic
Rule license: Elastic License v2
Setup
editSetup
If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2,
events will not define event.ingested
and default fallback for EQL rules was not added until version 8.2.
Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
event.ingested
to @timestamp.
For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
Rule 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/