Fortinet Discovers Synology Cloud Station Drive DLL Preloading Vulnerability
Fortinet's FortiGuard Labs has discovered a DLL preloading vulnerability in Synology Cloud Station Drive.
Synology's Cloud Station Drive is an application designed to synchronize files between your Synology NAS and PCs via the Internet, ensuring that your data is always up-to-date and enabling you to easily access your files. Even when the Internet connection is not available, you can still view and edit your files offline, and all the changes made will be automatically synced to your Synology NAS and PCs once the Internet connection is restored.
Synology Cloud Station Drive before 4.2.5-4396 is susceptible to multiple DLL preloading vulnerabilities. The issue occurs when the application looks to load a DLL for execution and loads an attacker provided malicious DLL instead of the legitimate DLL. The application generally follows a specific search path to locate the DLL. The vulnerability can be exploited by a simple file write (or potentially an over-write) which results in a foreign DLL (located in the current working directory) running under the context of the application.
Users should apply the solution provided by Synology.
Fortinet reported the vulnerability to Synology on July 7, 2017.
Synology released patch for it on August 30, 2017.
This vulnerability was discovered by Kushal Arvind Shah of Fortinet's FortiGuard Labs.