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Microsoft Internet Explorer JavaScript OnLoad Handler Remote Code Execution Vulnerability

Risk
High

Date Discovered
05-28-2005

Description
Microsoft Internet Explorer is affected by a remote code execution vulnerability.

This vulnerability presents itself when the browser handles a JavaScript 'onLoad' handler in conjunction with an improperly initialized 'window()' JavaScript function.

This issue may be exploited to execute arbitrary remote code in the context of the user running the affected application. Failed exploitation attempts likely result in the application crashing.

Symantec Enterprise Security Manager

Symantec Enterprise Security Manager posted an update to the OS Patch Policy that detects and reports systems that are not patched against this vulnerability. Click here for the advisory released December 13, 2005.

Symantec Enterprise Security Manager Network Assessment Module

Symantec Enterprise Security Manager Network Assessment Module detects and reports this vulnerability. Click here for the advisory released December 22, 2005.

Symantec Vulnerability Assessment

Symantec Vulnerability Assessment detects and reports this vulnerability. Click here for the advisory released December 13, 2005.

Platforms Affected
Microsoft Windows 2000 Advanced Server
Microsoft Windows 2000 Advanced Server SP1
Microsoft Windows 2000 Advanced Server SP2
Microsoft Windows 2000 Datacenter Server
Microsoft Windows 2000 Datacenter Server SP1
Microsoft Windows 2000 Datacenter Server SP2
Microsoft Windows 2000 Professional
Microsoft Windows 2000 Professional SP1
Microsoft Windows 2000 Professional SP2
Microsoft Windows 2000 Server
Microsoft Windows 2000 Server SP1
Microsoft Windows 2000 Server SP2
Microsoft Windows 2000 Terminal Services
Microsoft Windows 2000 Terminal Services SP1
Microsoft Windows 2000 Terminal Services SP2
Microsoft Windows 95
Microsoft Windows 98
Microsoft Windows 98SE
Microsoft Windows ME
Microsoft Windows NT Enterprise Server 4.0
Microsoft Windows NT Enterprise Server 4.0 SP1
Microsoft Windows NT Enterprise Server 4.0 SP2
Microsoft Windows NT Enterprise Server 4.0 SP3
Microsoft Windows NT Enterprise Server 4.0 SP4
Microsoft Windows NT Enterprise Server 4.0 SP5
Microsoft Windows NT Enterprise Server 4.0 SP6
Microsoft Windows NT Enterprise Server 4.0 SP6a
Microsoft Windows NT Server 4.0
Microsoft Windows NT Server 4.0 SP1
Microsoft Windows NT Server 4.0 SP2
Microsoft Windows NT Server 4.0 SP3
Microsoft Windows NT Server 4.0 SP4
Microsoft Windows NT Server 4.0 SP5
Microsoft Windows NT Server 4.0 SP6
Microsoft Windows NT Server 4.0 SP6a
Microsoft Windows NT Terminal Server 4.0
Microsoft Windows NT Terminal Server 4.0 SP1
Microsoft Windows NT Terminal Server 4.0 SP2
Microsoft Windows NT Terminal Server 4.0 SP3
Microsoft Windows NT Terminal Server 4.0 SP4
Microsoft Windows NT Terminal Server 4.0 SP5
Microsoft Windows NT Terminal Server 4.0 SP6
Microsoft Windows NT Workstation 4.0
Microsoft Windows NT Workstation 4.0 SP1
Microsoft Windows NT Workstation 4.0 SP2
Microsoft Windows NT Workstation 4.0 SP3
Microsoft Windows NT Workstation 4.0 SP4
Microsoft Windows NT Workstation 4.0 SP5
Microsoft Windows NT Workstation 4.0 SP6
Microsoft Windows NT Workstation 4.0 SP6a
Microsoft Windows Server 2003 Datacenter Edition
Microsoft Windows Server 2003 Datacenter Edition 64-bit
Microsoft Windows Server 2003 Enterprise Edition
Microsoft Windows Server 2003 Enterprise Edition 64-bit
Microsoft Windows Server 2003 Standard Edition
Microsoft Windows Server 2003 Web Edition
Microsoft Windows XP Home
Microsoft Windows XP Professional

Components Affected
Microsoft Internet Explorer 5.0.1 SP4
Microsoft Internet Explorer 5.0.1 SP3
Microsoft Internet Explorer 5.0.1 SP2
Microsoft Internet Explorer 5.0.1 SP1
Microsoft Internet Explorer 5.0.1
Microsoft Internet Explorer 5.5 SP2
Microsoft Internet Explorer 5.5 SP1
Microsoft Internet Explorer 5.5
Microsoft Internet Explorer 6.0 SP2
Microsoft Internet Explorer 6.0 SP1
Microsoft Internet Explorer 6.0

Recommendations
Run all client software as a non-privileged user with minimal access rights.
Execute all software as a user with minimal privileges. Software that may potentially handle malicious content should by insulated with additional precautions such as restrictive environments.

Do not follow links provided by unknown or untrusted sources.
Users should refrain from following links that originate from unknown or questionable sources.

Set web browser security to disable the execution of script code or active content.
It may be possible to prevent successful exploitation by disabling script code and active content support within the client browser. It should be noted that this mitigation tactic might adversely affect legitimate Web sites that rely on the execution of browser based script code.

Implement multiple redundant layers of security.
As it may be possible that this issue will be leveraged to execute code, memory protection schemes are recommended. Memory protection schemes such as non-executable stack/heap configurations and randomly mapped memory segments will complicate exploitation of memory corruption vulnerabilities.

Microsoft has released fixes for supported operating system versions. Fixes for Internet Explorer 5.5 SP 2 running on Windows ME and Internet Explorer 6 SP 1 running on Windows 98/98SE/ME can be obtained through the Microsoft Update Web site or the Windows Update Web site.


Microsoft Internet Explorer 5.0.1 SP4:

Microsoft Patch Cumulative Update for Internet Explorer 5.01 Service Pack 4 (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=4005B74A-D6E6-4A32-A3B1-276686B4A428&displaylang=en

Microsoft Internet Explorer 5.0.1 SP3:
Microsoft Internet Explorer 5.0.1 SP2:
Microsoft Internet Explorer 5.0.1 SP1:
Microsoft Internet Explorer 5.0.1:
Microsoft Internet Explorer 5.5 SP2:
Microsoft Internet Explorer 5.5 SP1:
Microsoft Internet Explorer 5.5:
Microsoft Internet Explorer 6.0 SP2:
Microsoft Internet Explorer 6.0 SP1:
Microsoft Patch Cumulative Update for Internet Explorer 6 SP1 (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=A8443CD2-D98D-427B-9F0E-BD7E19FCB994&displaylang=en

Microsoft Internet Explorer 6.0:
Microsoft Patch Cumulative Update for Internet Explorer for Windows XP Service Pack 2 (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=E4B5BA57-D4F2-4798-9154-2869E371C9D1&displaylang=en
Microsoft Patch Cumulative Update for Internet Explorer for Windows Server 2003 (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=9D70FB20-C7C9-43AF-A864-6DBC9A542CC6&displaylang=en
Microsoft Patch Cumulative Update for Internet Explorer for Windows Server 2003 64-bit Itanium Edition (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=1EE790B9-E596-4344-AEC3-FCB3289D7E9C&displaylang=en
Microsoft Patch Cumulative Update for Internet Explorer for Windows Server 2003 x64 Edition (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=8E9C23E5-7988-42DA-A8BD-2C1A534BF995&displaylang=en
Microsoft Patch Cumulative Update for Internet Explorer for Windows XP x64 Edition (KB905915)
http://www.microsoft.com/downloads/details.aspx?familyid=E1652B4A-6339-4B31-8ACF-D2A844C24F70&displaylang=en

References
Source: Microsoft Security Advisory (911302)
URL: http://www.microsoft.com/technet/security/advisory/911302.mspx

Source: Microsoft Security Bulletin MS05-054
URL: http://www.microsoft.com/technet/security/Bulletin/MS05-054.mspx

Source: Technet Security
URL: http://www.microsoft.com/technet/treeview/default.asp?url=/technet/itsolutions/security/default.asp

Credits
Discovery is credited to Benjamin Tobias Franz.


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