Dear Brian Eaton, --Monday, September 11, 2006, 7:35:08 PM, you wrote to 3APA3A@xxxxxxxxxxxxxxxx: >> It means, if authentication schema is NTLM-compatible (it must be for >> compatibility with pre-Windows 2000 hosts and some network >> applications, like Outlook Express), attacker can use compromised >> account to access network resources without having access to 2-factor >> authentication device. How long he can retain this access depends on >> how often account's NT key is changed (usually with password change, >> but actually depends on implementation of authentication system and >> may be never). BE> Is this RSA whitepaper an example of what you are talking about? BE> http://tinyurl.com/pb5n7 BE> The whitepaper refers to Kerberos tickets, but the mechanism sounds BE> like it could work with NTLM as well. BE> I think the situation you are pointing out is where an authentication BE> process requires an initial two-factor authentication, but then issues BE> some kind of session key that takes a very long time to expire. That BE> would seem to defeat the purpose of the two-factor auth. In case of Kerberos authentication there is also "session key" (TGT) which is issued by default for 10 hours. But Kerberos controls IP address of the client, it reduces the impact of ticket stealing. In case of NTLM, this control is impossible, because domain controller is contacted by server, not by client. Regarding NTLM support it's not absolutely clear, but according to this: -=-=-=-=-=- quote ? In this scenario, the first time end users are asked to RSA SecurID authenticate to Microsoft Windows, users are asked for their Windows password. The RSA ACE/Sever software captures and stores it. From then on, RSA Authentication Manager software provides the Windows password to the Windows login process for the end user who does not need to enter it. -=-=-=-=-=- NT key is probably generated and used by SecurID. And probably it's worst possible case: NT key is derived from windows password and is never changed. Of cause, it needs to be checked. If NTLM works (e.g. you can connect to file server behind NAT or through mapped port) - it is. -- ~/ZARAZA http://www.security.nnov.ru/
