Microsoft Security Advisory (2794220)

ronjor · Dec 29, 2012

Vulnerability in Internet Explorer Could Allow Remote Code Execution

Published: Saturday, December 29, 2012

Version: 1.0
General Information
Executive Summary

Microsoft is investigating public reports of a vulnerability in Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8. Internet Explorer 9 and Internet Explorer 10 are not affected by the vulnerability. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability through Internet Explorer 8.

The vulnerability is a remote code execution vulnerability that exists in the way that Internet Explorer accesses an object in memory that has been deleted or has not been properly allocated. The vulnerability may corrupt memory in a way that could allow an attacker to execute arbitrary code in the context of the current user within Internet Explorer. An attacker could host a specially crafted website that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the website.

On completion of this investigation, Microsoft will take the appropriate action to protect our customers, which may include providing a solution through our monthly security update release process, or an out-of-cycle security update, depending on customer needs.

We are actively working with partners in our Microsoft Active Protections Program (MAPP) to provide information that they can use to provide broader protections to customers. In addition, we are actively working with partners to monitor the threat landscape and take action against malicious sites that attempt to exploit this vulnerability.

Microsoft continues to encourage customers to follow the guidance in the Microsoft Safety & Security Center of enabling a firewall, applying all software updates and installing anti-virus and anti-spyware software.

Mitigating Factors:

By default, Internet Explorer on Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2 runs in a restricted mode that is known as Enhanced Security Configuration. This mode mitigates this vulnerability.
By default, all supported versions of Microsoft Outlook, Microsoft Outlook Express, and Windows Mail open HTML email messages in the Restricted sites zone. The Restricted sites zone, which disables script and ActiveX controls, helps reduce the risk of an attacker being able to use this vulnerability to execute malicious code. If a user clicks a link in an email message, the user could still be vulnerable to exploitation of this vulnerability through the web-based attack scenario.
An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
In a web-based attack scenario, an attacker could host a website that contains a webpage that is used to exploit this vulnerability. In addition, compromised websites and websites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker's website.

Recommendation. Please see the Suggested Actions section of this advisory for more information.
Click to expand...

http://technet.microsoft.com/en-us/security/advisory/2794220

ronjor · Dec 29, 2012

swiat
29 Dec 2012 2:52 PM

Today, the MSRC released Security Advisory 2794220 alerting customers to limited, targeted attacks affecting customers using Internet Explorer 6, 7, and 8. Internet Explorer 9 and Internet Explorer 10 users are safe.

More information about the vulnerability and exploit

In this particular vulnerability, IE attempts to reference and use an object that had previously been freed. The components of an exploit for such a vulnerability are typically the following:

Javascript to trigger the Internet Explorer vulnerability
Heap spray or similar memory preparation to ensure the memory being accessed after it has been freed is useful
A way around the ASLR platform-level mitigation
A way around the DEP platform-level mitigation

We’ve analyzed four exploits, all the targeted attacks we have seen. They are all very similar:
Click to expand...

https://blogs.technet.com/b/srd/arc...nternet-explorer-8-users.aspx?Redirected=true

siljaline · Dec 29, 2012

Thanks for this, Ron.

Dogbiscuit · Dec 31, 2012

The flaw has reportedly been used to exploit Windows PC users who visited the Web site for the Council on Foreign Relations, a nonpartisan think tank specializing in U.S. foreign policy and international affairs. The site has been hosting the malicious code since at least December 21, Darien Kindlund, senior staff scientist at security advisor FireEye, wrote in a blog Friday.

"We can also confirm that the malicious content hosted on the website does appear to use Adobe Flash to generate a heap spray attack against Internet Explorer version 8.0 (fully patched), which was the source of the zero-day vulnerability," Kindlund wrote.
Click to expand...

http://news.cnet.com/8301-1009_3-57561277-83/ie-flaw-may-allow-windows-pcs-to-be-hijacked-microsoft-warns/

Baserk · Jan 5, 2013

ISC Diary post, EMET 3.5: The Value of Looking Through an Attacker's Eyes. link

Using MetaSploit on an XP SP3 host, it is shown how EMET 3.5 will simply resist heap spray and ROP attacks from this exploit.

'...Repeating the exploit with EMET 3.5 running, we see an interesting notification before Internet Explorer gracefully terminates. EMET detects the heap-spray and terminates.
Ok. But what if the exploit didn’t include a heap-spray? We disable heap-spray detection and repeat the exploit again. This time, we choose to mitigate ROP attacks by looking for a technique known as a StackPivot. (you may remember from the exploit source code). The exploit still fails as EMET detects the StackPivot.
Maybe, it doesn’t use a stack pivot. Maybe it uses some unheard of technique that bypass DEP by making a call to one of the several Win32 API calls that can turn off DEP such as VirtualProtect(). Nope! Again, EMET detects the call and notices it has been called from a userland process and not the kernel. It terminates Internet Explorer and notifies the user.'

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