Microsoft Internet Explorer Malformed URI Buffer Overflow Vulnerability



Date Discovered

April 12, 2005


A buffer overflow vulnerability is reported in Microsoft Internet Explorer. This issue is due to insufficient boundary verification of user-supplied input data causing a fixed-sized memory buffer to be overrun when attempting to copy data into it. This vulnerability allows attacker-supplied machine code to be executed in the context of the affected application.

Technologies Affected

  • 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
  • Microsoft Internet Explorer 6.0 SP2 do not use


Run all software as a nonprivileged user with minimal access rights.
Non-administrative software should be run as non-administrative users with the least privileges required. This will limit the potential damage that successful exploitation may achieve.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Network intrusion detection systems should be deployed to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to requests that include NOP sleds and unexplained incoming and outgoing traffic. This may indicate exploitation attempts or activity that results from successful exploitation.

Do not accept communications that originate from unknown or untrusted sources.
Users should not follow suspicious links, or open email that originates from unknown or untrusted sources.

Review and adjust according to policy any default configuration settings.
Users should disable HTML rendering of email messages in Outlook and Outlook Express, as this will limit the possibility of successful exploitation.

Microsoft has released updates to address this vulnerability on supported platforms. Internet Explorer 6 for Windows Server 2003 SP 1 including 64-Bit Edition is not affected by this issue. Windows XP Professional x64 Edition is also not affected. Microsoft has released fixes for Windows 98, Windows 98 Second Edition, and Windows Millennium Edition. These updates are available from the Windows Update Web site: Localized Slovenian and Slovakian fixes are available for Windows 98, Windows 98 Second Edition, and Windows Millennium Edition as well. Please see the referenced Microsoft bulletin for more information.



3APA3A and axle@bytefall are credited for the discovery of this vulnerability.

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