Re: NTLM HTTP Authentication is insecure by design - a new writeup by Amit Klein

Dear Amit Klein (AKsecurity),

--Monday, July 18, 2005, 9:40:32 PM, you wrote to bugtraq_at_securityfocus.com:

AKA> NTLM HTTP Authentication
AKA> (and possibly other connection-oriented
AKA> HTTP authentication and authorization protocols)
AKA> is insecure by design

 NTLM authentication is insecure by design for external authentication,
 because of "single signon" ideology. NTLM authentication can be used
 for NTLM proxy attack. For example, attacker who can hijack or spoof
 server connection with NTLM authentication can use this connection to
 access different Web server, mail server or file server with client's
 credentials. This is known for many years and was discussed for many
 times. Few years ago Internet Explorer was patched to use NTLM
 authentication only for local network zone. Local network are hosts
 with NetBIOS name (for example WEBSRV, excluded by default from proxy)
 and list of proxy exclusions.

 So, under default configuration, NTLM will not be used through proxy
 server, at least in Internet Explorer.

-- 
~/ZARAZA
http://www.security.nnov.ru/