Zero-Day Advisory

Fortinet Discovers Steganos Online VPN Shield DLL PreLoading Vulnerability


Fortinet's FortiGuard Labs has discovered a DLL preloading vulnerability in Steganos Online VPN Shield for Windows.

Steganos Online VPN Shield for Windows is a Virtual Private Network product to protect a user's identity and personal privacy using their anonymous VPN and proxy services. It allows users to anonymize all their online activities.

Steganos Online VPN Shield 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 Steganos.


Fortinet reported the vulnerability to Stegnos on May 21, 2018.

Steganos confirmed the vulnerability on July 13, 2018.

Steganos released patch for it on September 28, 2018.


This vulnerability was discovered by Kushal Arvind Shah of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.