Hi, I recently tested an RSA SecurID SID800 Token http://www.rsasecurity.com/products/securid/datasheets/SID800_DS_0205.pdf The token is bundled with some windows software designed to make user's life easier. Interestingly, this software provides a function which directly copies the current token code into the cut-and-paste buffer, when the token is plugged in into USB. This is weak by design. The security of these tokens is based on what RSA calls "two-factor user authentication": It takes both a secret (PIN) and the time-dependend Token-Code to authenticate. The security of the Token-Code depends on the assumption that the token is resistant against malware or intruders on the computer used for communication (web browser, VPN client,...). However, if the Token Code can be read over the USB bus, this assumption does not hold. A single attack on the PC where the token is plugged in would compromise both the PIN (e.g. with a keylogger) and the token itself (e.g. writing a daemon which continuously polls the token and forwards the token in real time to a remote attacker. Ironically this could make an attack even easier: If some malware simultaneously monitors the token and the keyboard, it is much easier to detect that the keystrokes are actually related to some login procedure: Whenever the 6-digit token code appears in the keyboard or cut-and-paste input stream, you can be pretty sure that in a sliding window of about the last 100-200 keystrokes both the PIN and the address of the server to login is contained. Makes it really easy to automatically detect secrets in the input stream. Thus, two different authentication methods are together weaker than each single one. regards Hadmut
