IE Update Fixes Remote Code Execution and Certificate Issues

Summary:

• This vulnerability affects: All current versions of Internet Explorer
• How an attacker exploits it: Mostly 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

Exposure:

In a security bulletin released as part of Patch Day, Microsoft describes an update that fixes a 23 new vulnerabilities that affect all current versions of Internet Explorer (IE). Microsoft rates the aggregate severity of these new flaws as Critical.

Most of the vulnerabilities described in this alert (22 of the 23) are memory corruption vulnerabilities, which share the same general scope and impact. If an attacker can lure you to a web page containing malicious web code, he can exploit these memory corruption vulnerabilities to execute code on your computer, inheriting your privileges. If you have local administrative privileges, which most Windows users do, the attack could potentially gain full control of your computer

The update also fixes a publicly reported certificate handling issue having to do with how IE handles extended validation (EV) certificates and wildcards. Attackers could leverage this flaw to help make their phishing sites look more legitimate. Though this issue is pretty bad, the memory corruption flaws pose even more risk. They alone should convince you to update IE as soon as you can.

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, and the vulnerabilities described in today’s bulletin are perfect for use in drive-by download attacks.

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 April IE security bulletin.

For All WatchGuard Users:

Good News! 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 some of the memory corruption vulnerabilities described in Microsoft’s alert:

• WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-1765)
• WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-2787)
• WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-2795)
• WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-2797)
• WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-2801)
• WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-2804)

Your XTM appliance should get this new IPS signature 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:

• MS Security Bulletin MS14-037

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

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