Zscaler’s ThreatLabz research team has uncovered a significant security concern within Microsoft 365, involving SketchUp (SKP) files, leading to Microsoft temporarily disabling their support.
These vulnerabilities emerged following Microsoft’s introduction of SKP file format support in June 2022 to enhance the 3D capabilities of the Office suite. Zscaler discovered 117 unique vulnerabilities when analyzing how Microsoft 365 parsed SKP files. These vulnerabilities included issues like heap buffer overflow, integer overflow, and use-after-free problems, rendering the system vulnerable to remote code execution attacks.
Furthermore, an examination of SKP files embedded with images revealed that FreeImage, a third-party library last updated in 2018, was employed to parse these images. Subsequently, Zscaler identified 97 unique vulnerabilities in FreeImage, many of which were successfully reproduced within Microsoft 365. These vulnerabilities could only be exploited if an attacker tricked a user into opening a specifically crafted SketchUp file.
Microsoft took action by issuing three CVEs and providing patches in April, May, and June, marking them as remote code execution (RCE) bugs. However, Zscaler was able to bypass these patches, resulting in Microsoft temporarily disabling support for the SketchUp file format.
This revelation underscores the ongoing challenge of maintaining the security of complex file format integrations in widely used software like Microsoft 365 and the need for constant vigilance and updates to protect against emerging threats.