Back Office Web Administration Authentication Bypass
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 (email@example.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 Administrator
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 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 mor details.
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 @