On Tue, Aug 07, 2018 at 05:47:01PM +0200, Janusz Dziedzic wrote: > Regarding article: > https://hashcat.net/forum/thread-7717.html This has a bit vague description of the attack and some of the terms used are not really accurate. It seems to describe an alternative way of initiating a dictionary attack on WPA/WPA2-PSK passphrase using PMKID instead of the more commonly used EAPOL-Key frames captured from a 4-way handshake from an authorized station. The PMKID being in the PMKID KDE (not RSN element) in EAPOL-Key msg 1/4 Key Data field. This does not describe significant difference to the actual offline dictionary attack. That said, there is some difference in the number of needed SHA1 operations since PMKID can be derived in a single HMAC-SHA1 operation from PMK while Key MIC calculation requires first deriving PTK(KCK) and then Key MIC. In addition, it is not very clear how common it is for deployed APs to send out the PMKID in EAPOL-Key msg 1/4. Based on some of the reports, that is not really the behavior of majority of implementations. > Does it mean FT-PSK is not secure anymore? I don't see FT-PSK being discussed here. The "roaming" in the description seems to be referring to use PMKSA caching, not FT. Use of weak passphrases with either WPA-PSK or FT-PSK is more or less as secure (or insecure, as it may be more appropriate to say here) against dictionary attacks as they are with the use of a valid 4-way handshake capture to trigger that attack. Use of a properly random passphrase/PSK makes that dictionary attack impractical due to the computation need. > Base on article someone with: > 4 x GeForce GTX 1080 > get PSK in 1 minute? That is an example based on a very weak passphrase and the attacker actually knowing the last two characters of it.. In other words, this is just showing how long it takes to run a dictionary (or maybe even full brute force) attack against six unknown characters. That is not a good example to use to estimate how long it would take to recover any unknown passphrase (minimum eight characters) and certainly not for any properly random passphrase. -- Jouni Malinen PGP id EFC895FA _______________________________________________ Hostap mailing list Hostap@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/hostap
