7 ms·
Predicting, Decrypting, and Abusing WPA2/802.11 Group Keys [pdf]
- evgen 9y agoWPA2 is toast. Ref to the CVEs that will make a lot of network admins hate Monday: https://twitter.com/nick_lowe/status/919527451570638848 https://twitter.com/nick_lowe/status/919527451570638848 And some background: https://eprint.iacr.org/2016/475.pdf https://eprint.iacr.org/2016/475.pdf
- evgen 9y agoAlso worth nothing that the attack in the OP is on TKIP, but the KRACK attack that will be revealed tomorrow is based upon problems with the RNG (the example RNG, which apparently everyone used, is trivial to break and the protocol is also kind enough to provide you with a huge chunk of the entropy used in seeding the RNG. D'oh!)
- mschuster91 9y agoThis comment should be made the top comment. Thanks for the information. I guess this implies not "only" passive eavesdropping but also network access in environments without a MAC address filter (not that these can't be spoofed regardless)?
- sengork 9y agoSpoofed yes but they're hard to guess in advance without prior knowledge of the device's MAC address.
- djrogers 9y agoMAC addresses are broadcast in the clear regularly, so any device doing that without some randomization is ripe for the picking.
- willstrafach 9y agoWorth noting also: You vannot randomize it when connected to a Wi-Fi network.
- deleted 9y ago[deleted]
- throwaway613834 9y agoWPA2 in general, or just WPA2-TKIP?
- evgen 9y agoWPA2 in general. The 4-way handshake is vulnerable. Might be patchable, but there is a ton of embedded stuff out there that will never get updated...
- cm2187 9y agoI guess the question is whether only the AP needs to be patched or the client as well.
- ztjio 9y agoIn fact it is only clients that need patching. However, sometimes AP's are also clients. Disable any such features if you have them and are not depending on them.
- vermilingua 9y agoIt has already been patched by some vendors, but you're right, if the IoT has given us anything, it's tonnes of unpatchable consumer gear.
- YouKnowBetter 9y ago> WPA2 is toast. No it is not. It is "just" one part of the 4 way handshake. Source: https://www.krackattacks.com/ https://www.krackattacks.com/
- billh 9y agoHere's the CCC talk with the author of this white paper: https://www.youtube.com/watch?v=KJWd-_BDC_g https://www.youtube.com/watch?v=KJWd-_BDC_g
- evgen 9y agoThere are also a BlackHat Europe 2017 paper that is apparently a strong foreshadowing on the attack.
- londons_explore 9y ago"We initialize the random number generator with the system uptime, then use it to make crypto keys" - really?!? "We also publish the system uptime in an unencrypted broadcast message to save you the effort of even bruteforcing it". Does nobody do security reviews on this stuff, or are these weaknesses there deliberately? The line between incompetence and malice really is thin here...
- cm2187 9y agoAnd on a device equipped with a radio, it's not very hard to generate entropy.
- gsich 9y agoThe radio might not be exposed to the OS. If it's a Fullmac device, you usually don't have access to the radio stuff. Even with Softmac, there's not a guarantee.
- cm2187 9y agoI am sure that's a problem on the client, but on the AP, the manufacturer controls both the hardware and the OS.
- gsich 9y agoNot necessarily. Again with fullmac devices you don't control the complete hardware.
- cm2187 9y agoYeah but if you are Cisco, Netgear or DLink, and tell your supplier that you want a function to access noise in the signal, or you want to get a true random number based on that noise, I am sure they could accommodate in future generations of their chip at an insignificant cost.
- simosx 9y agoThe article says that only WPA2-TKIP is vulnerable to the downgrade, therefore running WPA2 with only AES should be fine.
- krallja 9y agoStay tuned for tomorrow's KRACK announcement, then.
- ealexhudson 9y agoThis is a 2016 paper. Tomorrow's details are apparently about forcing nonce reuse in most WPA2 implementations. Don't let the date fool you into thinking it's old news being discussed!
- arkadiyt 9y agoDetails for tomorrow's WPA2 attack will be published to: https://www.krackattacks.com/ https://www.krackattacks.com/
- deleted 9y ago[deleted]
- sengork 9y agoHere is a good summary of the situation right now: https://www.alexhudson.com/2017/10/15/wpa2-broken-krack-now/ https://www.alexhudson.com/2017/10/15/wpa2-broken-krack-now/
- krallja 9y agoWell, if there's one piece of (somewhat) good news around this and https://www.krackattacks.com/ https://www.krackattacks.com/, it's that TLS and VPNs will become even more common. Where did WEP and WPA2 come from, anyway? What's the historical reason we aren't all using TLS to connect to our APs?
- stygiansonic 9y agoMy guess is that for most people, provisioning a wireless network using a shared secret (or just a button press, ala the broken WPS) is easier than having to setup a CA and sign/distribute certificates. (Not defending WEP or WPA in anyway)
- gruez 9y agoThe only reason TLS works is because of CAs. What could be the CAs for APs?
- azernik 9y agoWPA2 Enterprise use a central RADIUS server for authentication, with separate credentials for each user, and a (separately-distributed) certificate for the server. It's just not practical for consumer and small-business setups.
- gsich 9y agoSomewhat true. Setting up a Freeradius is not hard. Problem is that you need another device that is running 24/7.
- azernik 9y agoThe bit that's less practical for consumer setup is more the cert distribution and setup of separate credentials for each user. (The RADIUS server could even be built into the router in a consumer product.)
- 9y ago
- madmod 9y agoI understand that the info to answer my question may not be public yet. I would greatly appreciate an an answer by someone who can explain when it is. If an attacker had recorded encrypted WiFi traffic in the past and then performed one of these attacks could they see the traffic? (I know TLS is used for a lot of traffic, but in time that will be broken too.) It seems to me that a patient attacker could gain a lot of sensitive info given enough time. Is this assumption flawed? I would love to hear why/why not. (Nonces make decryption of large amounts of TLS traffic impractical?) What about the impact of just knowing DNS lookups? (Real world info on DNS caching? Does DNSSEC stop this? Is it widely implemented?) What if a data broker recorded a lot of encrypted WiFi traffic at a public place like a mall? (Could they learn MAC addresses? mDNS device names? DNS lookups? I bet a lot of tracking cookies and other advertiser tokens don’t bother with TLS which could get them emails and more.) Someone recording encrypted WiFi traffic from a sensitive network may have enough motive to do something this long-term and the attack would be (electronically) undetectable. Most people rarely change their passwords and at a minimum this would give an attacker knowledge of the internal network, intranet sites, and services used by targets.
- cjbprime 9y agoI expect they could, yes; WPA2 doesn't offer forward secrecy. But WPA2 never offered much anyway. If you're on mall wifi, you can already see unencrypted traffic for everyone else, because the client keys are derivable from the shared passphrase (which presumably everyone at the mall has been told) and overhearing the four-way handshake when someone joins. And! You can even fake a disconnect message that forces the four-way handshake to happen again, if you weren't around when the client originally joined. All of which is to say, WPA2 in passphrase (PSK) mode never actually provided meaningful encryption against other people on the network. :( Someone forgot to tell the protocol designers that Diffie-Hellman exists. Using Diffie-Hellman would achieve both removing the exploit where you observe the four-way handshake, and providing for forward secrecy too.
- mysterypie 9y ago> * If you're on mall wifi, you can already see unencrypted traffic for everyone else* Without contradicting your observation, I want to mention that virtually anything important you do on the Internet these days--from online banking to Google searches to reading Hacker News--is protected by a second independent layer of encryption: HTTPS. I'm not excusing the WPA2 flaws, but I do think that your bank info, web searches, and Hacker News comments are secure even at the mall. If someone can offer a credible explanation of why online banking or other HTTPS activity is insecure on public wifi, I'd like to hear it please.
- Viper007Bond 9y agoHere's an article on Ars about it: https://arstechnica.com/information-technology/2017/10/severe-flaw-in-wpa2-protocol-leaves-wi-fi-traffic-open-to-eavesdropping/ https://arstechnica.com/information-technology/2017/10/sever...