Microsoft Internet Explorer Double Byte Character Set Handling Address Bar Spoofing Vulnerability



Date Discovered

October 12, 2004


It is reported that Microsoft Internet Explorer is prone to a vulnerability that may allow a malicious Web page to spoof the address bar of the browser. This vulnerability presents itself due to a malfunction that occurs when certain double byte characters are encountered. As a result, this vulnerability will only affect computers that are configured to employ double byte character sets. This could be used to lure Web users into a false sense of trust since a malicious or spoofed site may pose as a site that is trusted by the user.

Technologies Affected

  • Avaya DefinityOne Media Servers
  • Avaya IP600 Media Servers
  • Avaya Modular Messaging (MSS) 1.1.0
  • Avaya Modular Messaging (MSS) 2.0.0
  • Avaya S3400 Message Application Server
  • Avaya S8100 Media Servers
  • Microsoft Internet Explorer 5.0.1
  • 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 5.5
  • Microsoft Internet Explorer 5.5 SP1
  • Microsoft Internet Explorer 5.5 SP2
  • Microsoft Internet Explorer 6.0
  • Microsoft Internet Explorer 6.0 SP1


Run all software as a nonprivileged user with minimal access rights.
As a general security precaution, all non-administrative tasks should be performed as an unprivileged user with minimal access rights.

Do not follow links provided by unknown or untrusted sources.
Users should be wary of visiting links provided through unsolicited email or otherwise presented by an unfamiliar or untrusted source.

Do not accept communications that originate from unknown or untrusted sources.
Users should avoid accepting or opening HTML email due to the possibility that it may be used as an attack vector for this or other vulnerabilities. Client support for HTML email should be disabled and if possible, HTML email should also be filtered at the gateway.

Microsoft has released a cumulative update for supported versions of Internet Explorer to address this and other vulnerabilities. Avaya has released an advisory that acknowledges this vulnerability for Avaya products. Customers are advised to follow Microsoft.s guidance for applying patches. Please see the referenced Avaya advisory at the following location for further details:



Discovery of this vulnerability is credited to Liu Die Yu.

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