CVE-2023-33176
Vulnérabilité moyenne dans bigbluebutton (bigbluebutton)
Description
BigBlueButton is an open source virtual classroom designed to help teachers teach and learners learn. In affected versions are affected by a Server-Side Request Forgery (SSRF) vulnerability. In an `insertDocument` API request the user is able to supply a URL from which the presentation should be downloaded. This URL was being used without having been successfully validated first. An update to the `followRedirect` method in the `PresentationUrlDownloadService` has been made to validate all URLs to be used for presentation download. Two new properties `presentationDownloadSupportedProtocols` and `presentationDownloadBlockedHosts` have also been added to `bigbluebutton.properties` to allow administrators to define what protocols a URL must use and to explicitly define hosts that a presentation cannot be downloaded from. All URLs passed to `insertDocument` must conform to the requirements of the two previously mentioned properties. Additionally, these URLs must resolve to valid addresses, and these addresses must not be local or loopback addresses. There are no workarounds. Users are advised to upgrade to a patched version of BigBlueButton.
Gravité et risque d'exploitation
CVE-2023-33176 obtient un score CVSS de 4.8/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.47 %, ce qui la place devant 39.5 % des CVE référencées.
Que faire ?
- Vérifiez si bigbluebutton (versions < 2.5.18, >= 2.6.0, < 2.6.9) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.
Références
- https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-3q22-hph2-cff7
- https://github.com/bigbluebutton/bigbluebutton/pull/18045
- https://github.com/bigbluebutton/bigbluebutton/pull/18052
- https://github.com/bigbluebutton/bigbluebutton/commit/43394dade595d0707384e4878357901537352415
- https://github.com/bigbluebutton/bigbluebutton/commit/b18aff32e65a47f1eb2c800e86dcfc7a8fb05e71
