NT user (who is locked changing his/her password by administrator ) can bypass the security policy and Change the password.

From: Syed Mohamed A (SyedMAat_private)
Date: Wed Mar 06 2002 - 01:07:05 PST

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    Hi,
    Our PT team found the following vulnerability in security policy
    implementation with NT Server and IIS 4.0.
    
    NT user (who is locked changing his/her password by administrator)  can
    bypass the security policy and Change the password.
    
    Vulnerable:
    
    Microsoft Windows NT Server 4.0 + IIS 4.0 + Service pack 6.0 
    
    Description:
    
    Valid NT user can bypass the administrator security policy "user cannot
    change password" and can change his/her password through web based ".HTR"
    application. 
    
    Valid NT user whose account is locked changing his/her password by
    administrator i.e. (Administrator applied the policy " user cannot change
    password") can  still "Change his/her password through IIS Web service
    http://iisserver/iisadmpwd/aexp3.htr ". This is possible with disabled
    accounts also. 
    
    Enter valid user id and password (who can not change his/her password).Enter
    new password. It is by passing the security policy "user can not change
    password" and password got changed.
    
    The following files can also be used for the same
    
    http://iis-server/iisadmpwd/aexp2.htr
    http://iis-server/iisadmpwd/aexp2b.htr
    http://iis-server/iisadmpwd/aexp4.htr
    
    Vendor status
    
    Microsoft was informed about this. 
    
    Response from Microsoft
    
    	"The particular policy you've mentioned, locking users out of
    changing 
    Passwords, isn't something that this tool, when developed, was designed to
    account for.
    
    Again, though, we want to reiterate that .HTR is a deprecated technology
    and we very strongly urge you to unmap .htr if at all possible.  The
    preferred method of handling accounts through HTML pages is through the
    use of ADSI now.  As I noted, we are looking to see if we can provide an
    ASP based application to replace the HTR-based application at some
    point." 
    
    Solution
    
    .HTR should be disabled by unmapping. Avoid using  .HTR based password
    changing application.
    
    
    Best Regards
    		 
    Syed Mohamed A
    Technical Specialist- Technology & Practices 
    InnerFrame - The Technology infrastructure services provider
    Division of The Microland Group, India
    www.innerframe.com
    
    
    email:   syedmaat_private   
    Tel:       91-80-5503313 to 18  extn. 153
    Fax:      91-80-5503319
     
    
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