Microsoft Internet Explorer CreateTextRange Remote Code Execution Vulnerability



Date Discovered

March 22, 2006


Microsoft Internet Explorer is susceptible to a remote code-execution vulnerability. This issue is due to a flaw that results in an invalid table-pointer dereference. Remote attackers may exploit this issue to crash affected browsers or to execute arbitrary machine code in the context of affected users. Microsoft has reported that this issue does not affect the March 20, 2006 release of Internet Explorer 7 Beta 2 Preview.

Technologies Affected

  • Microsoft Internet Explorer 5.0.1 SP1
  • Microsoft Internet Explorer 5.0.1 SP2
  • Microsoft Internet Explorer 5.0.1 SP3
  • Microsoft Internet Explorer 5.0.1 SP4
  • Microsoft Internet Explorer 6.0
  • Microsoft Internet Explorer 6.0 SP1
  • Microsoft Internet Explorer 6.0 SP2 do not use
  • Microsoft Internet Explorer 7.0 beta2


Do not follow links provided by unknown or untrusted sources.
Do not visit websites of unknown or questionable integrity from production systems.

Set web browser security to disable the execution of JavaScript.
Since the exploitation of this issue requires executing malicious script code in web clients, consider disabling support for script code and active content within a client browser. Note that this mitigation tactic might adversely affect legitimate websites that rely on the execution of browser-based script code.

Implement multiple redundant layers of security.
Various memory-protection schemes (such as non-executable and randomly mapped memory segments) may hinder an attacker's ability to exploit this vulnerability to execute arbitrary code.

Run all software as a nonprivileged user with minimal access rights.
Due to the potential for arbitrary code execution, run the browser as an unprivileged user with minimal access rights. This will limit the consequences of exploitation.

The Internet Explorer 7 Beta 2 Preview released on March 20, 2006 is not affected by this vulnerability. Users of earlier Internet Explorer 7 beta releases are advised to upgrade. Updates are not currently available for other Internet Explorer releases. Microsoft has released a cumulative update to address this issue. Please see the referenced advisories for further information. Reportedly, the fixes provided in MS06-013 may cause unintended breakage with certain ActiveX controls. Symantec has not confirmed this. Before deploying this patch in production environments, users should thoroughly test the patch to ensure that it doesn't interfere with other software.



Discovered by Joshua Heyer.

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