- This vulnerability affects: All current versions of Internet Explorer, running on all current versions of Windows
- How an attacker exploits it: Typically, by enticing one of your users to visit a malicious web page
- Impact: Various, in the worst case an attacker can execute code on your user’s computer, gaining complete control of it
- What to do: Deploy the appropriate Internet Explorer patches immediately, or let Windows Automatic Update do it for you
In a security bulletin released today as part of Patch Day, Microsoft describes 13 new vulnerabilities in Internet Explorer (IE) 9.0 and earlier, running on all current versions of Windows. Microsoft rates the aggregate severity of these new flaws as Critical.
The 13 vulnerabilities differ technically, but many of them share the same general scope and impact. More than half the flaws are remote code execution vulnerabilities having to do with how IE handles various HTML objects, elements, and properties. If an attacker can lure one of your users to a web page containing malicious code, he could exploit any one 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.
The remaining issues include less severe cross-site scripting (XSS) flaws and information disclosure vulnerabilities.
If you’d like to know more about the technical differences between these flaws, see the “Vulnerability Information” section of Microsoft’s bulletin. Technical differences aside, the remote code execution flaws pose significant risk to IE users, and allow attackers to launch drive-by download attacks. Furthermore, attackers often hijack legitimate web sites and force them to serve this kind of malicious web code. So these types of flaws can affect you no matter what types of web sites you frequent on the Internet. If you use IE, you should download and install the cumulative update immediately.
These updates fix serious issues. You should download, test, and deploy the appropriate IE patches 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 IE security bulletin.
For All WatchGuard Users:
These attacks travel as normal-looking HTTP traffic, which you must allow if your network users need to access the World Wide Web. Therefore, the patches above are your best solution.
That said, WatchGuard’s Gateway Antivirus and Intrusion Prevention Service can often prevent these sorts of attacks, or the malware they try to distribute. We highly recommend you enable our security services on your WatchGuard XTM and XCS appliances.
Microsoft has released patches to fix these vulnerabilities.
This alert was researched and written by Corey Nachreiner, CISSP.