Zero-Day Advisory

Fortinet Discovers Mozilla Firefox Vulnerability


Fortinet's FortiGuard Labs has discovered a vulnerability in the way that Mozilla Firefox loads DLL files.


Users should apply the solution provided by Mozilla.

FortiGuard Labs has posted a document that recommends further mitigation strategy for this vulnerability.

Additional Information

Firefox loads a certain library ("dwmapi.dll") as part of its startup routine. If an attacker can successfully plant a malicious DLL with this filename on the victim's system, Firefox can mistakenly load the malicious DLL from its current working directory instead of the intended library. For this to occur, the system must not have a valid "dwmapi.dll" file in the search path (ie: Windows XP). This DLL is only loaded at startup so a successful attack requires that Firefox is not currently running when it is asked to open an HTML file and accompanying DLL from the current working directory.


Haifei Li 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.