Rule Category

SERVER-OTHER -- Snort has detected traffic exploiting vulnerabilities in a server in the network.

Alert Message

SERVER-OTHER OpenSSL alternative chains certificate forgery attempt

Rule Explanation

The X509_verify_cert function in crypto/x509/x509_vfy.c in OpenSSL 1.0.1n, 1.0.1o, 1.0.2b, and 1.0.2c does not properly process X.509 Basic Constraints cA values during identification of alternative certificate chains, which allows remote attackers to spoof a Certification Authority role and trigger unintended certificate verifications via a valid leaf certificate. Impact: CVSS base score 6.5 CVSS impact score 2.5 CVSS exploitability score 3.9 confidentialityImpact LOW integrityImpact LOW availabilityImpact LOW Details: Ease of Attack:

What To Look For

Known Usage

No public information

False Positives

No known false positives

Contributors

Talos research team. This document was generated from data supplied by the national vulnerability database, a product of the national institute of standards and technology. For more information see [nvd].

MITRE ATT&CK Framework

Tactic:

Technique:

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

CVE

Additional Links

CVE Additional Information

CVE-2015-1793
The X509_verify_cert function in crypto/x509/x509_vfy.c in OpenSSL 1.0.1n, 1.0.1o, 1.0.2b, and 1.0.2c does not properly process X.509 Basic Constraints cA values during identification of alternative certificate chains, which allows remote attackers to spoof a Certification Authority role and trigger unintended certificate verifications via a valid leaf certificate.
Details
Severity Base Score6.5
Impact Score2.5 Exploit Score3.9
Confidentiality ImpactLOW Integrity ImpactLOW
Availability ImpactNONE Access Vector
Authentication Ease of Access