Fortinet Discovers Yandex Disk DLL Preloading Vulnerability
Summary
Fortinet's FortiGuard Labs has discovered a DLL preloading vulnerability in Yandex Disk.
Yandex Disk is a cloud service by Yandex that lets users store files on "cloud" servers and share them with others online. The service is based on syncing data between different devices. The Yandex Disk for Windows tool can be used to sync data between the device endpoint and Yandex Cloud account.
Yandex Disk for Windows is susceptible to a DLL preloading vulnerability. The issue occurs when the application looks to load a DLL for execution and an attacker provides a malicious DLL to use instead. 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 running under the context of the application.
Solutions
Users should apply the solution provided by Yandex.
Timeline
Fortinet reported the vulnerability to Yandex on June 15, 2017.
Yandex confirmed the vulnerability on June 29, 2017.
Yandex patched the vulnerability on June 29, 2017.