A buffer overflow in the HTR ISAP extension on IIS servers could permit an intruder to interrupt the normal operation of IIS or possibly execute arbitrary code with the privileges of the HTR extension.
HTR is a server-side scripting technology for IIS which has largely been supplanted by ASP.
There is a buffer overflow in the HTR ISAPI extension. By submitting a malicious HTR request, and intruder can exploit this buffer overflow.
An intruder can interrupt the normal operation of the IIS server. In addition, an intruder may be able to use this vulnerability to execute arbitrary code with the privileges of the HTR ISAPI extension. On IIS 4.0, this permits administrative control of the oeprating system; on IIS 5.0 and 5.1, this permits access with the privileges of the IWAM_computername account.
Apply a patch as decribed in MS02-018.
In addition to applying the patch (or if the patch cannot be applied) we strongly recommend disabling the HTR ISAPI extension. It has been the source of a number of vulnerabilities, including
Our thanks to Microsoft Corporation upon whose advisory this document is based. Microsoft has publicly thanked Dave Aitel of @Stake and Peter Grundl of KPMG for reporting this vulnerability.
|Date First Published:||2002-04-10|
|Date Last Updated:||2004-02-23 22:20 UTC|