- These vulnerabilities affect: Internet Explorer 9 (IE 9) and earlier
- How an attacker exploits them: By enticing one of your users to visit a malicious web page
- Impact: An attacker can execute code on your user’s computer, often gaining complete control of it
- What to do: Install Microsoft’s Internet Explorer updates immediately, or let Windows Automatic Update do it for you
As part of today’s Patch Day, Microsoft released a security bulletin describing four new security vulnerabilities that affect 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 four vulnerabilities differ technically, but share the same general scope and impact. In short, they are all “remote code execution” vulnerabilities having to do with how IE handles various specially crafted HTML objects. If an attacker can lure one of your users to a web page containing maliciously crafted 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.
If you’d like to know more about the technical differences between these flaws, see the “Vulnerability Information” section of Microsoft’s bulletin. Details 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 this kind of malicious web code. 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.
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 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 these attacks 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.