Quantum Secular Labs / Blog / Advisories

CVE-2017-17672: Vbulletin: Insecure deserialization

CVE-2017-17672 is rated critical with a CVSS v3.0 base score of 9.8 and affects Vbulletin. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

In vBulletin through 5.3.x, there is an unauthenticated deserialization vulnerability that leads to arbitrary file deletion and, under certain circumstances, code execution, because of unsafe usage of PHP's unserialize() in vB_Library_Template's cacheTemplates() function, which is a publicly exposed API. This is exploited with the templateidlist parameter to ajax/api/template/cacheTemplates.

Severity breakdown

CVSS v3.0 9.8: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-502: Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Affected products

  • Vbulletin: from 5.0.1 up to and including 5.3.3; 5.0.0 beta_11; 5.0.0 beta_28

References