Cumulative Patch Corrects Drive-by Download Flaws in IE9

Severity: High

9 August, 2011

Summary:

  • This vulnerability affects: All current versions of Internet Explorer, including IE9
  • How an attacker exploits it: In most cases, 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

Exposure:

In a security bulletin released today as part of Patch Day, Microsoft describes seven new vulnerabilities in Internet Explorer (IE) 9.0 and earlier versions, running on all current versions of Windows (including Windows 7 and Windows Server 2008). Microsoft rates the aggregate severity of these new flaws as Critical.

The seven vulnerabilities differ technically, but the three worst share the same general scope and impact. These three issues involve remote code execution flaws having to do with how IE handles various HTML objects and URIs. If an attacker can lure one of your users to a web page containing malicious web 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 that case, the attacker could exploit these flaws to gain complete control of the victim’s computer.

The remaining vulnerability consists mostly of Information Disclosure flaws.

Keep in mind, today’s attackers commonly hijack legitimate web pages and booby-trap them with malicious code. Typically, they do this via hosted web ads or through SQL injection and 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 remote code execution flaws in IE pose significant risk and allow attackers to launch drive-by download attacks. You should download and install the IE cumulative patch immediately.

Solution Path:

These patches fix serious issues. You should download, test, and deploy the appropriate IE patches immediately, or let Windows Automatic Update do it for you.

* Note: These flaws do not affect Windows Server 2008 administrators who installed using the Server Core installation option.

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.

Status:

Microsoft has released patches to fix these vulnerabilities.

References:

This alert was researched and written by Corey Nachreiner, CISSP.

About Corey Nachreiner

Corey Nachreiner has been with WatchGuard since 1999 and has since written more than a thousand concise security alerts and easily-understood educational articles for WatchGuard users. His security training videos have generated hundreds of letters of praise from thankful customers and accumulated more than 100,000 views on YouTube and Google Video. A Certified Information Systems Security Professional (CISSP), Corey speaks internationally and is often quoted by other online sources, including C|NET, eWeek, and Slashdot. Corey enjoys "modding" any technical gizmo he can get his hands on, and considers himself a hacker in the old sense of the word.

Trackbacks/Pingbacks

  1. Cumulative Patch Corrects Drive-by Download Flaws in IE9 | microreksa - August 10, 2011

    [...] Cumulative Patch Corrects Drive-by Download Flaws in IE9 [...]

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