Today we released Security Advisory 2458511 to address a new vulnerability that could impact Internet Explorer users if they visit a website hosting malicious code. As of now, the impact of this vulnerability is extremely limited and we are not aware of any affected customers. The exploit code was discovered on a single website which is no longer hosting the malicious code. When a website is discovered to host malicious software, we work through legal channels to take the site down. These kinds of attempts to exploit systems and the people using technology are the activity of criminals. Microsoft takes this very seriously and where possible, we will take legal action against those responsible.
Internet Explorer 9 Beta users are not affected by this issue and any customers who wish to upgrade their browser to this version can do so freely at www.microsoft.com/ie. Impacted versions include Internet Explorer 6, 7 and 8, although our ongoing investigation confirms that default installations of Internet Explorer 8 are unlikely to be exploited by this issue. This is due to the defense in depth protections offered from Data Execution Prevention (DEP), which is enabled by default in Internet Explorer 8 on all supported Windows platforms. For supported versions of Windows running earlier versions of Internet Explorer, please review this blog post from our Security Research & Defense team describing how to enable DEP.
The Security Advisory also details a workaround that customers can apply that will protect all affected versions of IE from this issue. We are working to put have a Microsoft Fix it in place for easy implementation of the workaround. Our Security Research & Defense team has also provided a detailed write up on how the workaround protects against the vulnerability.
We have initiated our Software Security Incident Response Process (SSIRP) to manage this issue and are sharing detailed information through the Microsoft Active Protections Program (MAPP). Our 70 global MAPP partners, including leading providers of anti-virus and anti-malware products, provide protections for an estimated one billion customers worldwide. If your protection provider is in our MAPP program, you can contact them concerning the status of providing protections for this issue as it is likely that updated malware signatures in these products will offer further protection. For customers of Microsoft Security Essentials and our Forefront security products, new signatures will be published today offering additional protection. Internet Explorer 8 also includes SmartScreen technology which helps provide protection against many types of socially engineered malware and phishing attacks, and which earlier this year reached the milestone of blocking over 1 billion attempts to download malware. In certain circumstances, SmartScreen may also help to protect customers in this case.
We are working to develop a security update to address this attack against our customers. The issue does not meet the criteria for an out-of-band release. However, we are monitoring the threat landscape very closely and if the situation changes, we will post updates here on the MSRC blog.
As always, we encourage Internet users to follow the "Protect Your Computer" guidance of enabling a firewall, applying all software updates and installing anti-virus and anti-spyware software. Additional information can be found at: www.microsoft.com/protect.
Group Manager, Response Communications
Trustworthy Computing Group
Edited to add: The Fix it is available now from the Knowledge Base article for this Advisory.