CVE-2024-35235
Vulnérabilité moyenne dans cups (OpenPrinting)
Description
OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.8 and earlier, when starting the cupsd server with a Listen configuration item pointing to a symbolic link, the cupsd process can be caused to perform an arbitrary chmod of the provided argument, providing world-writable access to the target. Given that cupsd is often running as root, this can result in the change of permission of any user or system files to be world writable. Given the aforementioned Ubuntu AppArmor context, on such systems this vulnerability is limited to those files modifiable by the cupsd process. In that specific case it was found to be possible to turn the configuration of the Listen argument into full control over the cupsd.conf and cups-files.conf configuration files. By later setting the User and Group arguments in cups-files.conf, and printing with a printer configured by PPD with a `FoomaticRIPCommandLine` argument, arbitrary user and group (not root) command execution could be achieved, which can further be used on Ubuntu systems to achieve full root command execution. Commit ff1f8a623e090dee8a8aadf12a6a4b25efac143d contains a patch for the issue.
Gravité et risque d'exploitation
CVE-2024-35235 obtient un score CVSS de 4.4/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 2.42 %, ce qui la place devant 83.9 % des CVE référencées.
Que faire ?
- Vérifiez si cups (versions <= 2.4.8) 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/OpenPrinting/cups/security/advisories/GHSA-vvwp-mv6j-hw6f
- https://github.com/OpenPrinting/cups/commit/ff1f8a623e090dee8a8aadf12a6a4b25efac143d
- https://git.launchpad.net/ubuntu/+source/apparmor/tree/profiles/apparmor.d/abstractions/user-tmp#n21
- https://github.com/OpenPrinting/cups/blob/aba917003c8de55e5bf85010f0ecf1f1ddd1408e/cups/http-addr.c#L229-L240
- http://www.openwall.com/lists/oss-security/2024/06/11/1
- http://www.openwall.com/lists/oss-security/2024/06/12/4
- http://www.openwall.com/lists/oss-security/2024/06/12/5
- https://lists.debian.org/debian-lts-announce/2024/06/msg00001.html