- This vulnerability affects: All current versions of Internet Explorer
- How an attacker exploits it: By enticing one of your users to visit a web page containing malicious content
- Impact: Various, in the worst case an attacker can execute code on your user’s computer, potentially 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 seven new vulnerabilities that affect all current versions of Internet Explorer (IE). Microsoft rates the aggregate severity of these new flaws as Critical.
The seven vulnerabilities differ technically, but the five most serious ones share the same general scope and impact, and involve various memory corruption flaws having to do with how IE handles certain HTML objects. If an attacker can lure one of your users to a web page containing malicious web code, he could exploit any one of these five vulnerabilities to execute code on that user’s computer, inheriting that user’s privileges. Typically, Windows users have local administrative privileges. In that case, the attacker could exploit these flaws to gain complete control of the victim’s computer.
The remaining two vulnerabilities are elevation of privilege flaws that attackers might use in conjunction with other attacks.
Keep in mind, today’s attackers often hijack legitimate web pages and booby-trap them with malicious code. Typically, they do this via hosted web ads or through SQL injection and cross-site scripting (XSS) attacks. Even recognizable and authentic websites could pose a risk to your users if hijacked in this way.
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 memory corruption flaws in IE pose significant risk. You should download and install the IE cumulative patch 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 December 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. Make sure to use our security services, and keep they’re signatures up to date. 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.
Microsoft has released patches to fix these vulnerabilities.
- MS Security Bulletin MS13-097
This alert was researched and written by Corey Nachreiner, CISSP (@SecAdept).
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