On 9/9/06, Lyal Collins <lyal.collins@xxxxxxxxxxxxx> wrote:
If there's malware on the machine, and there is a connected USB token, then authentication is only as good as the password - malware can probe the connected token as often as desired.
<snip>
In theory, with trusted data paths everywhere (internal to worksation as well as he network) OTP is better than passwords alone. But since this data patch assumption is rarely 100% valid, OTP is as good as a password alone. In the situation where data paths are trust-able, OTP is a somewhat better than passwords alone.
If you think about it in terms of how long an attacker has to act, I think you'll come to a different conclusion. Two-factor auth is better than password alone even when the end user is typing OTPs into a machine that is completely and totally rooted. The key phrase in your analysis is "connected token." Once the token is disconnected, the malware no longer has access to the authentication data. When a password is stolen it could be usable for months. When an OTP is stolen it is usable for hours, if that. Two-factor auth reduces the risk because it reduces the length of time of the compromise.
Does the risk justify the costs involved (tokens, token management, authentication host, and trusted data paths)?
That is the big question. Even if you are willing to pay for two-factor, transactional authentication might provide better value. Regards, Brian
