Today we released Security Advisory 2488013 to notify customers of a new publicly-disclosed vulnerability in Internet Explorer (IE). This vulnerability affects all versions of IE. Exploiting this vulnerability could lead to unauthorized remote code execution inside the iexplore.exe process. Proof...

DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization) have proven themselves to be important and effective countermeasures against the types of exploits that we see in the wild today. Of course, any useful mitigation technology will attract scrutiny, and over the past year there...

Today we released Security Advisory 2458511 notifying customers of limited attacks leveraging an Internet Explorer vulnerability. The beta version of Internet Explorer 9 is not affected while Internet Explorer 6, 7, and 8 are affected. So far the attacks we have seen only target Internet Explorer versions...

Yesterday we heard reports of a commercially available exploit that bypasses DEP. This exploit was made available to a limited number of major security vendors (Antivirus, IDS, and IPS vendors) and government CERT agencies. We wanted to use this opportunity to give an overview of current customer risk...

Yesterday, the MSRC released Microsoft Security Advisory 979352 alerting customers to limited, sophisticated attacks targeting Internet Explorer 6 customers. Today, samples of that exploit were made publicly available. Before we get into the details I want to make one thing perfectly clear. The attacks...

This morning we released five security bulletins , all of them having a bulletin maximum severity rating of Critical and two having a bulletin maximum exploitability index rating of "1" (Consistent exploit code likely). We wanted to just say a few words about each bulletin to help you prioritize your...

Over the past few months we have discussed a few different defense in depth mitigations (like GS [ pt 1 , pt2 ], SEHOP , and DEP [ pt 1 , pt 2 ]) which are designed to make it harder for attackers to successfully exploit memory safety vulnerabilities in software. In addition to the mitigations that we...

We have mentioned DEP in several recent blog posts ( 1 , 2 , 3 , and 4 ). This blog post will answer: What is DEP? How can you enable DEP? What are the risks in enabling different modes of DEP? This is the first of a two-part blog series on DEP as a mitigation technology. What is DEP...

In our previous blog post , we explained how DEP works and how to determine if / how a process opted-in to DEP. Now we will demonstrate how DEP can be used to mitigate the risk of a real-world attack. We published a security advisory in February describing an Excel vulnerability in fully-patched Excel...

IE8 behavior notes MS09-019 contains the fix for the IE8 vulnerability responsibly disclosed by Nils at the CanSecWest pwn2own competition (CVE-2009-1532). Nils exploited this vulnerability on an IE8 build that did allow .NET assemblies to load in the Internet Zone. The final, released build of...