1. Symantec/
  2. Security Response/
  3. Attack Signatures/
  4. HTTP MS IE VML Fill Method BO

HTTP MS IE VML Fill Method BO

Severity: High

This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.

Description

This signature detects an attempt to exploit a vulnerability in the Vector Markup Language by detecting a malformed VML fill tag.

Additional Information

Microsoft Internet Explorer is prone to a buffer-overflow vulnerability.

The vulnerability arises because of an error in the processing of Vector Markup Language documents in 'Vgx.dll'. When Internet Explorer is used to view a maliciously designed Vector Markup Language document containing overly long input to the 'fill' method, a buffer overflow occurs.

An attacker can exploit this issue to execute arbitrary code within the context of the affected application. The method by which this vulnerability is currently being exploited will typically terminate Internet Explorer.

This vulnerability is currently being exploited in the wild as Trojan.Vimalov.

This issue affects Internet Explorer version 6.0 on a fully patched system. Previous versions may also be affected.

Affected

  • Microsoft Internet Explorer 6.0
  • Microsoft Internet Explorer 6.0 SP1
  • Microsoft Windows 2000 Advanced Server SP4
  • Microsoft Windows 2000 Datacenter Server SP4
  • Microsoft Windows 2000 Professional SP4
  • Microsoft Windows 2000 Server SP4
  • Microsoft Windows Server 2003 Datacenter Edition
  • Microsoft Windows Server 2003 Datacenter Edition Itanium 0
  • Microsoft Windows Server 2003 Datacenter Edition Itanium SP1
  • Microsoft Windows Server 2003 Datacenter Edition Itanium SP1 Beta 1
  • Microsoft Windows Server 2003 Datacenter Edition SP1
  • Microsoft Windows Server 2003 Datacenter x64 Edition
  • Microsoft Windows Server 2003 Enterprise Edition
  • Microsoft Windows Server 2003 Enterprise Edition Itanium 0
  • Microsoft Windows Server 2003 Enterprise Edition Itanium SP1
  • Microsoft Windows Server 2003 Enterprise Edition Itanium SP1 Beta 1
  • Microsoft Windows Server 2003 Enterprise Edition SP1
  • Microsoft Windows Server 2003 Enterprise x64 Edition
  • Microsoft Windows Server 2003 Standard Edition
  • Microsoft Windows Server 2003 Standard Edition SP1
  • Microsoft Windows Server 2003 Standard x64 Edition
  • Microsoft Windows Server 2003 Web Edition
  • Microsoft Windows Server 2003 Web Edition SP1
  • Microsoft Windows XP 64-bit Edition
  • Microsoft Windows XP 64-bit Edition SP1
  • Microsoft Windows XP 64-bit Edition Version 2003
  • Microsoft Windows XP 64-bit Edition Version 2003 SP1
  • Microsoft Windows XP Home
  • Microsoft Windows XP Home SP1
  • Microsoft Windows XP Home SP2
  • Microsoft Windows XP Media Center Edition
  • Microsoft Windows XP Media Center Edition SP1
  • Microsoft Windows XP Media Center Edition SP2
  • Microsoft Windows XP Professional
  • Microsoft Windows XP Professional SP1
  • Microsoft Windows XP Professional SP2
  • Microsoft Windows XP Professional x64 Edition
  • Microsoft Windows XP Tablet PC Edition
  • Microsoft Windows XP Tablet PC Edition SP1
  • Microsoft Windows XP Tablet PC Edition SP2

Response

Workaround

The following workarounds may help defend against the exploitation of this vulnerability:

- Set Internet and Local intranet security zone settings to 'High'.
- Restrict websites to only your trusted sites.
- Disable JavaScripting in the browser.

As of September 19, 2006, Symantec has made available antivirus definitions to detect this issue.

Microsoft has released detailed workaround information regarding this issue; please see the referenced advisory for more information.

Reportedly, attackers have found a method of exploiting this issue without the use of JavaScript. Disabling scripting may therefore not be an effective workaround.

A third-party, temporary fix is available from the Zeroday Emergency Response Team (ZERT). This fix has not been verified by Symantec, and is not supported by Microsoft. Please see the reference section for further information.
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