The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server with a computer. The Nextcloud Desktop Client invokes its uninstaller script when being installed to make sure there are no remnants of previous installations. In versions 3.0.3 through 3.2.4, the Client searches the Uninstall.exe file in a folder that can be written by regular users. This could lead to a case where a malicious user creates a malicious Uninstall.exe, which would be executed with administrative privileges on the Nextcloud Desktop Client installation. This issue is fixed in Nextcloud Desktop Client version 3.3.0. As a workaround, do not allow untrusted users to create content in the C: system folder and verify that there is no malicious C:Uninstall.exe file on the system.
The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product’s direct control.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Desktop | Nextcloud | 3.0.3 (including) | 3.3.0 (excluding) |
| Nextcloud-desktop | Ubuntu | trusty | * |
| Nextcloud-desktop | Ubuntu | xenial | * |
This might allow attackers to execute their own programs, access unauthorized data files, or modify configuration in unexpected ways. If the product uses a search path to locate critical resources such as programs, then an attacker could modify that search path to point to a malicious program, which the targeted product would then execute. The problem extends to any type of critical resource that the product trusts. Some of the most common variants of untrusted search path are: