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Cumulative IE Update Corrects a Pile of Memory Corruption Flaws

Corey Nachreiner

Severity: High

Summary:

Exposure:

As part of today’s Patch Day, Microsoft released a security bulletin describing 17 new security vulnerabilities affecting Internet Explorer (IE). Microsoft describes all but one of these flaws as “memory corruption” vulnerabilities, but they don’t specify the exact type of memory corruption flaw. Regardless of which type of memory corruption flaws these are, they all share the same scope and impact. If an attacker can lure one of your users to a web page containing maliciously crafted HTML, he could exploit any of these vulnerabilities to execute code on that user’s computer, inheriting that user’s privileges. Typically, Windows users have local administrative privileges, in which case the attacker can exploit these flaws to gain complete control of the victim’s computer.

If you’d like more technical detail about these flaws, see the “Vulnerability Information” section of Microsoft’s bulletin. Technicalities aside, all of these remote code execution flaws pose significant risk to IE users, and allow attackers to launch drive-by download attacks. Attackers often hijack legitimate web sites and force them to serve malicious web code in something the industry calls a “watering hole” attack. So these types of flaws may affect you even when visiting legitimate, trusted web sites.

If you use IE, you should download and install Microsoft’s cumulative update immediately.

Solution Path:

You should download, test, and deploy the appropriate IE updates immediately, or let Windows Automatic Update do it for you. You can find links to the various IE updates in the “Affected and Non-Affected Software” section of Microsoft’s July IE security bulletin.

For All WatchGuard Users:

WatchGuard’s Gateway Antivirus and Intrusion Prevention services can often prevent these sorts of attacks, or the malware they try to distribute. For instance, our IPS signature team has developed signatures that can detect and block many of the memory corruption vulnerabilities described in Microsoft’s alert:

Your XTM appliance should get this new IPS update shortly.

Furthermore, our Reputation Enabled Defense (RED) and WebBlocker services can often prevent your users from accidentally visiting malicious (or legitimate but booby-trapped) web sites that contain these sorts of attacks. Nonetheless, we still recommend you install Microsoft’s updates to completely protect yourself from all of these flaws.

Status:

Microsoft has released patches to fix these vulnerabilities.

References:

This alert was researched and written by Corey Nachreiner, CISSP (@SecAdept).

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