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CVE-2025-42611 RouterOS Cert Bypass: Detection & IOCs

A certificate from any trusted CA bypasses auth on RouterOS 7.20 and earlier; hunt it with 9 detection rules, 3 IOCs and a free Splunk SPL rule.

Read the full threat intel for CVE-2025-42611 RouterOS Cert Bypass: Detection & IOCs →

Chapters

  1. 0:00The hookOne trusted certificate authority bypasses every service.
  2. 0:04The storyRouterOS uses one certificate store.
  3. 0:10Attack pathReportedly, any trusted certificate bypasses authentication.
  4. 0:29AttributionNo threat actor: this was defensive research.
  5. 0:33Indicators of compromiseNo malicious indicators were published.
  6. 0:39MITRE ATT&CK techniques5 ATT&CK techniques, from initial access to credential access.
  7. 0:43Remediation3 steps now: Upgrade RouterOS to 7.21 or later.
  8. 0:50Detection rules9 detection rules, in SPL, KQL and Sigma.
Transcript

0:00One trusted certificate authority bypasses every service.

0:05RouterOS uses one certificate store.

0:08Every service trusts it equally.

0:10Reportedly, any trusted certificate bypasses authentication.

0:14Attackers join CAPsMAN or connect to OpenVPN.

0:19Upgrade to 7.21 and review certificate trust settings.

0:23Manual trust-scope configuration is still required.

0:29No threat actor: this was defensive research.

0:34No malicious indicators were published.

0:395 ATT&CK techniques, from initial access to credential access.

0:443 steps now: Upgrade RouterOS to 7.21 or later.

0:519 detection rules, in SPL, KQL and Sigma.

0:56Threadlinqs. The unified security engineering platform.