BSSA-2023-01

Date	2023-07-25
Severity	Medium
Affected	BlueSpice Infrastructure: Ghostscript
Fixed in	Ghostscript 9.53.3 and 10.01.2
CVE	CVE-2023-36664

Problem

A bug in ghostscript can be exploited to run arbitrary code on the host machine using prepared PDF document. In BlueSpice, when a) PDFHandler is enabled and b) a PDF document is uploaded, a preview image is being generated using ghostscript. If an attacker uploads a prepared PDF, they can execute code on the server.

PDFHandler is not enabled by default, but many installations have set it active.

Solution

Upgrade Ghostscript to a fixed version and ensure the updated version is used by adding $wgPdfProcessor = '/usr/bin/gs'; to LocalSettings.php.

If upgrade of Ghostscript is not possible, disable the extension PDFHandler. This, however, removes the ability for BlueSpice to render PDF preview images.

Resources

• For Debian: https://www.debian.org/security/2023/dsa-5446
• For Debian10: Information on source package ghostscript (debian.org)
• For Ubuntu: https://launchpad.net/ubuntu/+source/ghostscript/9.50~dfsg-5ubuntu4.8

Acknowledgements

Found during an internal security audit.