Zero-Day Advisory

Fortinet Discovers Cisco Immunet Installer DLL Preloading Vulnerability

Summary

Fortinet's FortiGuard Labs has discovered a DLL preloading vulnerability in Cisco Immunet installer.

Cisco Immunet is a free, cloud-based, community-driven antivirus application, using the ClamAV and its own engine. The software is complementary with existing antivirus software. The application claims to be fast and to provide up-to-date protection against threats. Virus signature files are stored in the cloud, not on individual computers, so update downloads are not required. Once a virus is detected and blocked for one user, all other Immunet users receive the same protection almost instantly.

Cisco Immunet installer 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 Cisco.

Additional Information

Fortinet reported the vulnerability to Cisco on June 30, 2017.

Cisco confirmed the vulnerability on July 19, 2017.

Cisco patched the vulnerability on November 15, 2017.

Acknowledgement

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.