US-CERT Technical Cyber Security Alert TA06-270A
Systems Affected;
* Microsoft Windows
* Microsoft Internet Explorer
Overview
The Microsoft Windows WebViewFolderIcon ActiveX control contains an integer overflow vulnerability that could allow a remote attacker to execute arbitrary code.
I. Description
The Microsoft Windows WebViewFolderIcon ActiveX control contains an integer overflow vulnerability. An attacker could exploit this vulnerability through Microsoft Internet Explorer (IE) or any other application that hosts the WebViewFolderIcon control. More information is available in Vulnerability Note VU#753044.
Exploit code for this vulnerability is publicly available.
II. Impact
By convincing a user to open a specially crafted HTML document, such as a web page or HTML email message, a remote attacker could execute arbitrary code with the privileges of the user who is running the program that hosts the WebViewFolderIcon control.
III. Solution
Microsoft has not released an update for this vulnerability. Consider the following workarounds and best practices:
A. Disable the WebViewFolderIcon ActiveX control
To protect against this specific vulnerability, disable the WebViewFolderIcon control by setting the kill bit for the following: {844F4806-E8A8-11d2-9652-00C04FC30871}
Typically, you will have to manually create this registry key and DWORD titled “Compatibility Flags”. Use Registry Editor to edit/create the following registry key;
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{844F4806-E8A8-11d2-9652-00C04FC30871} Set the value of the Compatibility Flags DWORD value to 0x00000400.
More information about how to set the kill bit is available in Microsoft Support Document 240797.
http://support.microsoft.com/kb/240797/en-us
B. Disable ActiveX
To protect against this and other ActiveX and COM vulnerabilities, disable ActiveX in the Internet Zone and any other zone that might be used by an attacker.
C. Render email as plain text
To protect against this and other vulnerabilities that require a victim to load a malicious HTML document, configure email clients to render email as plain text.
D. Do not follow unsolicited links
To protect against this and other vulnerabilities that require a victim to load a malicious HTML document, do not follow unsolicited or untrusted links.
In order to convince users to visit their sites, attackers often use URL encoding, IP address variations, long URLs, intentional misspellings, and other techniques to create misleading links. Do not click on unsolicited links received in email, instant messages (IMs), web forums, or internet relay chat (IRC) channels. Type URLs directly into the browser to avoid these misleading links. While these are generally good security practices, following these behaviors will not prevent exploitation of this vulnerability in all cases, particularly if a trusted site has been compromised or allows cross-site scripting.
IDSG also advises;
1. Do not log into a Windows host as Administrator, if not needed. Instead, log in as a non-privileged user.
2. Do not add a non-privileged user account to the Administrators Group.
3. Use “run as” to run processes as needed.