Risk
High

Date Discovered
6/9/2009 12:00:00 AM

Description
Microsoft Internet Explorer is prone to a remote code-execution vulnerability.Attackers can exploit this issue to execute arbitrary code in the context of the user running the browser. Successful exploits will compromise the browser and possibly the computer. Failed attacks may cause denial-of-service conditions.

Technologies Affected
Microsoft Internet Explorer 6.0
Microsoft Internet Explorer 6.0 SP1
Microsoft Internet Explorer 7.0

Recommendations
Run all software as a nonprivileged user with minimal access rights.
To reduce the impact of latent vulnerabilities, always run nonadministrative software as an unprivileged user with minimal access rights.
Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to requests that include NOP sleds and unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.
Do not follow links provided by unknown or untrusted sources.
Web users should be cautious about following links to sites that are provided by unfamiliar or suspicious sources.
Filtering HTML from emails may help remove a possible vector for transmitting malicious links to users.
Set web browser security to disable the execution of script code or active content.
Since a successful exploit of this issue requires malicious code to execute in web clients, consider disabling support for script code and active content within the client browser. Note that this mitigation tactic might adversely affect legitimate websites that rely on the execution of browser-based script code.
Implement multiple redundant layers of security.
Memory-protection schemes (such as nonexecutable stack and heap configurations and randomly mapped memory segments) will complicate exploits of memory-corruption vulnerabilities.

The vendor has released an advisory along with fixes. Please see the references for details.

References
Source: Microsoft Security Bulletin MS09-019
URL: http://www.microsoft.com/technet/security/Bulletin/MS09-019.mspx

Source: Microsoft Internet Explorer Homepage
URL: http://www.microsoft.com/ie/

Credits
Tippingpoint and the Zero Day Initiative