Fortinet Discovers Citrix Receiver DLL Preloading Vulnerability
Fortinet's FortiGuard Labs has discovered a DLL preloading vulnerability in Citrix Receiver.
Citrix Receiver is the client component of XenDesktop or XenApp. Devices with Receiver installed are able to access full desktops via XenDesktop or individual applications via XenApp from a centralized host, such as a server or cloud infrastructure.
Citrix Receiver 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.
Users should apply the solution provided by Citrix Systems.
Fortinet reported the vulnerability to Citrix Systems on June 4, 2017.
Citrix Systems confirmed the vulnerability on July 28, 2017.
Citrix Systems patched the vulnerability on August 18, 2017.