- This vulnerability affects: All current versions of Internet Explorer, running on all current versions of Windows
- How an attacker exploits it: By enticing one of your users to visit a malicious web page
- Impact: 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
In a security bulletin released today as part of Patch Day, Microsoft describes six new vulnerabilities in Internet Explorer (IE) 8.0 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 for normal versions of Windows, and Moderate for Server versions of Windows.
The six vulnerabilities differ technically, but four of them share the same general scope and impact. These four issues involve various memory corruption flaws having to do with how IE handles various HTML elements and 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 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 two remaining vulnerabilities consist of Cross-Site or Cross-Domain Scripting (XSS) vulnerabilities. Among other things, an attacker might leverage this type of vulnerability to view information (such as cookies) from another domain or site, which he shouldn’t have access to; or to execute scripts with another domain or sites privileges.
Keep in mind, today’s attackers commonly hijack legitimate web pages and booby-trap them with malicious code. They do this via hosted web ads or through SQL injection 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.
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.
- Internet Explorer 5.01
- Internet Explorer 6.0
- Internet Explorer 7.0
- Internet Explorer 8.0
* 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.
Microsoft has released patches to fix these vulnerabilities.
This alert was researched and written by Corey Nachreiner, CISSP.