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From: NGSSoftware Insight Security Research (nisrngssoftware.com)
Date: Tue Apr 16 2002 - 09:08:47 CDT
NGSSoftware Insight Security Research Advisory
Name: Back Office Web Administration Authentication Bypass
Systems Affected: Microsoft's Back Office Web Administrator 4.0, 4.5
Vendor URL: http://www.microsoft.com
Author: David Litchfield (davidngssoftware.com)
Date: 17th April 2002
Advisory number: #NISR17042002A
Advisory URL: http://www.ngssoftware.com/advisories/boa.txt
Issue: Attackers can bypass the logon page and access the Back Office Web
With the Microsoft Back Office suite of products comes a web based
administration ASP based application that runs on IIS. Normally, to use the
administration pages a user must authenticate but NGSSoftware have
discovered that it is trivial to bypass this.
Each of the Back Office Web Administrator ASP pages checks to see if the
user has been authenticated but does this with the following snippet of code
If Request.ServerVariables("auth_type") = "" Then
Response.Status = "401 ACCESS DENIED"
This is the only "authorization/authentication" performed. As such it's
trivial to bypass:
GET /BOADMIN/BACKOFFICE/SERVICES.ASP HTTP/1.1
No credentials are required as, technically the auth_type envariable has
been set, regardless of whether a user name or password have been supplied.
Risk and Mitigating Factors
By default the Back Office Web Administrator is limited to the loopback
address (127.0.0.1) which means that it can't be accessed remotely. However,
it is not uncommon to change this to allow for remote administration; tying
the Administrator to the loopback address makes it somewhat useless.
Basic authentication also needs to be enabled which, again, is not uncommon.
For those that match this criteria they are strongly urged to obtain the the
patch from Microsoft. Please see
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q316838& for more
A check for this issue has also been added to Typhon II, NGSSoftware's
vulnerabilty assessment scanner. For more information about Typhon, please
see the NGSSite http://www.ngssoftware.com/.