tgstation-server's DreamMaker environment files outside the deployment directory can be compiled and ran by insufficiently permissioned users

Vulnerability Description

tgstation-server is a production scale tool for BYOND server management. Prior to 6.8.0, low permission users using the "Set .dme Path" privilege could potentially set malicious .dme files existing on the host machine to be compiled and executed. These .dme files could be uploaded via tgstation-server (requiring a separate, isolated privilege) or some other means. A server configured to execute in BYOND's trusted security level (requiring a third separate, isolated privilege OR being set by another user) could lead to this escalating into remote code execution via BYOND's shell() proc. The ability to execute this kind of attack is a known side effect of having privileged TGS users, but normally requires multiple privileges with known weaknesses. This vector is not intentional as it does not require control over the where deployment code is sourced from and _may_ not require remote write access to an instance's `Configuration` directory. This problem is fixed in versions 6.8.0 and above.

References

• https://github.com/tgstation/tgstation-server/security/advisories/GHSA-c3h4-9gc2-f7h4
• https://github.com/tgstation/tgstation-server/pull/1835
• https://github.com/tgstation/tgstation-server/commit/374852fe5ae306415eb5aafb2d16b06897d7afe4