Does the recent RSA attack make you less safe? You weren’t that safe to begin with.


Competing equipment vendors and security consultants are having a field day promoting the usual end of the world scenarios.  If you believe them, you should be wringing your hands because a major pillar of your security has been knocked down.

It’s just not true.  Your tokens weren’t providing you with that much security to begin with.

As the authors of the Zeus and similar trojans are gleefully aware, the security of one-time passwords is totally dependent on the security of the host system; that is, the PC you’re using to enter your one-time password (OTP).  And the host system is easily compromised with key loggers or similar malware.  Your OTP can be captured and quickly transmitted to an attacker. Or even easier, they can simply piggyback on your authenticated session.  So attackers have learned that rather than trying to guess your OTP, they can simply render them immaterial by side stepping the whole process.

Even if the host system can be trusted, the risk of an attacker guessing the OTP is quite low.  Let’s assume the attacker has knowledge of your token key and has a range of serial numbers.  That, along with your PIN and the time, will give him enough information to generate a correct password.  But a range of serial numbers, dozens to thousands, multiplied by the range of even a four digit PIN (many people seem to be surprised that they can be much longer) still gives you a key space in the millions.
Now of course, an automated script can try millions of passwords in just a few seconds.  But there’s no reason why you should give your attackers that many chances.  That’s like playing the lottery, and tickets are free.  Instead, simply limit the number of password tries to a small number, say 5-10.  You should have your systems lock out the account for a short period of time and alert you if there are too many password attempts.  That will effectively stop password guessing.

Token-based authentication using standard PCs is more about giving your users warm fuzzies rather than providing real security.  The RSA attack ultimately won’t affect your system security.

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