Microsoft Internet Explorer contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the user. Updates are available.
Description
Microsoft Internet Explorer versions 6.0 SP1 and prior and 7.0 contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code or crash the browser, resulting in a denial of service (DoS) condition.
This vulnerability exists due to memory errors that may occur as the result of processing malformed HTML content. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to visit a malicious website designed to trigger memory corruption in Internet Explorer. The resulting error condition could allow the attacker to cause Internet Explorer to crash or execute arbitrary code with the privileges of the user.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates.
Warning Indicators
Microsoft Internet Explorer versions 6.0 SP1 and prior and 7.0 are vulnerable on the following operating systems:
Windows 2000 SP4 and prior
Windows XP SP3 and prior
Windows XP Professional x64 Edition SP2 and prior
Windows Server 2003 SP2 and prior
Windows Server 2003 for Itanium-based Systems SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Vista SP1 and prior
Windows Vista x64 Edition SP1 and prior
Windows Server 2008 for 32-bit Systems
Windows Server 2008 for x64-based Systems
Windows Server 2008 for Itanium-based Systems
IntelliShield Analysis
Windows Vista systems may hold less risk due to built-in account privilege separation. Windows Server 2003 and Windows Server 2008 systems running Internet Explorer are also at a reduced risk for exploitation due to the Enhanced Security Configuration mode.
Systems most at risk are those that allow users to run applications with elevated privileges equivalent to the Administrator account. An exploit against such a system could allow the attacker to execute arbitrary code resulting in a complete system compromise.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the August 2008 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin for August 2008
Microsoft has addressed this vulnerability by correcting error handling within Internet Explorer.
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS08-045
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause Internet Explorer to crash or execute arbitrary code with the privileges of the user. On systems that grant users Administrator privileges, an attacker could execute code that may result in the complete compromise of the affected system. Systems running Windows Vista are less likely to be affected due to the additional controls placed on user accounts by default.
Technical Information
This vulnerability exists due to memory errors that may occur as the result of processing malformed HTML content. Internet Explorer may attempt to access previously deleted or uninitialized memory areas as the result of processing malicious HTML objects, resulting in the corruption of process memory. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to visit a malicious website. If successful, the attacker could leverage the resulting memory corruption to execute arbitrary code with the privileges of the user running Internet Explorer.
Safeguards
Administrators are advised to apply the appropriate software updates.
Administrators may consider configuring Internet Explorer to prompt users before running ActiveX controls and Active Scripting by setting the Internet and Local Intranet security zone settings to High. Alternately, administrators could disable ActiveX and Active Scripting in these security zones.
Users are advised not to open e-mail from untrusted sources and may consider reading e-mail in plain text format.
Users are advised not to follow unsolicited links. Users should verify the authenticity of an unexpected link from a trusted source prior to following it.
Users are advised to run applications with the least necessary privileges.
Patches/Software
Microsoft has released updated software at the following links:
Datacenter Edition Base | Datacenter Edition, 64-bit Base | Enterprise Edition Base | Enterprise Edition, 64-bit Base | Itanium-Based Systems Edition Base | Standard Edition Base | Standard Edition, 64-bit Base | Web Server Base | Web Server, 64-bit Base
Microsoft, Inc.
Windows Vista
Business Base, SP1 | Business x64 Edition Base, SP1 | Enterprise Base, SP1 | Enterprise x64 Edition Base, SP1 | Home Basic Base, SP1 | Home Basic x64 Edition Base, SP1 | Home Premium Base, SP1 | Home Premium x64 Edition Base, SP1 | Ultimate Base, SP1 | Ultimate x64 Edition Base, SP1
Microsoft, Inc.
Windows XP
Home Edition Base, SP1, SP2, SP3 | Professional Edition Base, SP1, SP2, SP3 | Professional x64 (AMD/EM64T) Base, SP2
Alerts and bulletins on the Cisco Security Intelligence Operations Portal are highlighted by analysts in the
Cisco Threat Operations Center and represent a subset of the comprehensive content that is available through Cisco Security IntelliShield Alert Manager Service.
This customizable threat and vulnerability alert service provides security staff with access to timely, accurate, and credible information about threats and vulnerabilities that may affect their environment. Cisco is pleased to offer a free trial of the service.
To register for full access, please visit the IntelliShield trial registration page.
LEGAL DISCLAIMER The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
