Remote Code Execution within Collabora Online jail with Macros Enabled

Vulnerability Description

Collabora Online is a collaborative online office suite based on LibreOffice. Macro support is disabled by default in Collabora Online, but can be enabled by an administrator. Collabora Online typically hosts each document instance within a jail and is allowed to download content from locations controlled by the net.lok_allow configuration option, which by default include the private IP ranges to enable access to the local network. If enabled, macros were allowed run executable binaries. By combining an ability to host executables, typically in the local network, in an allowed accessible location, with a macro enabled Collabora Online, it was then possible to install arbitrary binaries within the jail and execute them. These executables are restricted to the same jail file system and user as the document instance but can be used to bypass the additional limits on what network hosts are accessible and provide more flexibility as a platform for further attempts. This is issue is fixed in 24.04.12.4, 23.05.19, 22.05.25 and later macros.

References

• https://github.com/CollaboraOnline/online/security/advisories/GHSA-4jjq-vgqp-qw45