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I came across this question a while ago and read about hole 196.

Is there something I can install on my laptop to protect it against WPA2 Hole196?

Software (such as Snort or DecaffeintID) can be installed on some Windows and Linux laptops to detect ARP poisoning, though it's not practical to manually install software on large number of endpoints. Further, the software is not supported on most endpoints (e.g., iPhones, iPads, Blackberry, Windows Mobile, Windows 7, etc.) that will continue to be at risk from the WPA 2 Hole196 vulnerability. Besides, those softwares cannot stop a malicious insider from launching other Hole196 based attacks such as malware injection, port scanning, denial of service, etc.

My question is, technically speaking, what other things can I do to possibly cover myself?

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Karthik
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    I don't understand what you are talking about: which "malware injection, port scanning, denial of service, etc." techniques are related with "Hole196"? Port scanning is a legitimate non-intrusive remote examination technique of any network-connected computer. "open" vs. "closed" ports is not a secret. You just have to accept that. ARP poisoning is an Ethernet thing, it isn't specific to Wifi. – curiousguy May 14 '12 at 15:08

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Most security researchers consider "hole 196" to be more of a technical break than something that is very useful to the attacker. I think that the WPA-PSK handshake, and the lack of encryption for for management frames are far more serious threats.

Although hole 196 can be used in conjunction with these attacks. 1) de-auth a client, 2) capture the handshake when they re-auth and then brute force the challenge response 3) use hole 196 to obtain traffic

However, you can defend against hole 196 by using a VPN. The problem is that if someone else is authenticated to the wireless network then they are able to observe some of your traffic. Simple, if you use an SSL VPN to get out of the wireless network, then they won't be able to see anything useful.

rook
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  • "_Most security researchers consider "hole 196" to be more of a technical break than something that is very useful to the attacker._" It isn't either things. "_I think that the WPA-PSK handshake, [is] far more serious threats_" If you are using PSK you cannot be worried about said "hole 196". – curiousguy May 14 '12 at 15:52
  • @curiousguy Care to clarify that last statement? I thought Hole 196 applied to bot PSK and Enterprise implementations? So, how is it that we should not be worried about it? – Iszi May 14 '12 at 16:26
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    @Iszi The "just break the glass" vulnerability applies to all windows, opened or closed. It is much less **relevant** to opened windows. If you are worried about this vuln, you don't leave your windows open either (or you shouldn't). If you leave your windows open you should rather worry about the "just go through the open window without breaking the glass". The "hole 196" applies to all variants of WPA, but I can't see its relevance to a **Shared** (as in shared by every Wifi client) Key set-up. **If you worry about insiders you don't share the master key.** That would be insane. – curiousguy May 14 '12 at 16:44
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    @curiousguy and Rook - I think you agree on the same point. The insecurities of a [WPA2-PSK handshake](http://en.wikipedia.org/wiki/IEEE_802.11i-2004#The_Four-Way_Handshake) allows an eavesdropper to decrypt all traffic intended for another client, if they intercept the initial unencrypted nonce from the AP and also have the shared passphrase -- making it an "open window". If an insider didn't intercept the initial nonce, and has the shared passphrase they cannot decrypt all of the other users' traffic (but could do hole 196 for MITM-style attacks). – dr jimbob May 14 '12 at 17:37
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    @drjimbob "_If an insider didn't intercept the initial nonce_" then all they have to do is to force dissociation. – curiousguy May 16 '12 at 06:43
  • @dr jimbob decryption? I think you mean brute force the challenge response which is a hash, and yes curiousguy is right, you can de-auth anyone on a WPA or WEP network because management frames are in plain text and most clients will auto-reconnect. – rook May 16 '12 at 15:07
  • Rook - yes decryption. WPA2-PSK traffic (after the handshake) is encrypted/decrypted with AES with the pairwise transient key (PTK - specifically the 128-bit TK part). Again, I'm assuming its an insider attacker (we're talking hole 196) who has the pre-shared key (PSK). @curiousguy - good point about unencrypted management frames letting an attacker force dissociation. – dr jimbob May 16 '12 at 15:32
  • Knowing the PSK you can even setup **a rogue AP that cannot be distinguished from the legitimate ones**: clients could detect a BSSID change, but they cannot assume that there is only one AP for a given SSID as many AP could be part of the same ESSID. Of course the BSSID could also be cloned. Conclusion: **WPA*-PSK offers zero protection against insiders. Use WPA-Enterprise.** – curiousguy May 17 '12 at 19:36
  • @curiousguy can you site a source? – rook May 17 '12 at 20:14
  • @Rook A source for what statement? Again, **the PSK is the only secret master key** in the whole ESSID. All other informations are sent in clear-text in the air, or derived from the PSK and informations sent in the clear. Once you have given the PSK to a double-agent, you pretty much have an open unencrypted WLAN - inside a Faraday cage (outsiders cannot connect to the WLAN). – curiousguy May 17 '12 at 21:15
  • @Rook The proof that you can set-up a rogue AP is that you can set-up a legitimate AP. The source is "anyone who has configured a Wifi AP". (A rogue AP is any AP that you do not consider legitimate.) – curiousguy May 18 '12 at 08:56
  • @curiousguy Another thought, regarding WPA2-PSK and why those users should be worried about hole 196: WPS. Anyone using a system with WPS enabled by choice, ignorance, or because their system doesn't allow it to be disabled, should be absolutely concerned about this threat. The (relatively) recent vulnerability discovered in WPS would allow an *outsider* to join the network and then have the same access to Hole 196 as insiders. – Iszi May 20 '12 at 05:05
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Some obvious, albeit general, possibilities:

  • Use a wired network instead - this avoids the vulnerability altogether
  • Encrypt your critical traffic (at the application/endpoint level, since you don't trust the network).
  • Put non-technical controls in place against malicious insiders. (e.g. background checks of employees.)
Rory Alsop
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Graham Hill
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    @curiousguy - Wired is preferred to Wireless when mobility is not an issue. You need physical access to the actual ethernet cable/router to do any sort of eavesdropping/DOS attack. If I want to DOS a wifi connection its as simple as turning on a nearby interfering microwave oven or other source of noise in the bandwidth range. If I want to monitor whether packets are being sent (which may be useful in and of itself; indicating nearby activity) with wifi its transparent to anyone reasonably nearby who is listening. – dr jimbob May 14 '12 at 17:03
  • @drjimbob "_If I want to DOS a wifi connection its as simple as turning on a nearby interfering microwave oven_" Choosing a low Wifi channel helped me with my Wifi vs. MW conflict (the 5 GHz band would help even more, I don't have such Wifi card). EOAnectode. Of course what you say is correct, and **it applies to to any radio communication** that is not very focussed, or uses military, unpredictable channel hoping. There is nothing special with the Wifi protocol here, **it's about the physical media**. Note that DSL is wired and also has similar EM noise issues. – curiousguy May 14 '12 at 17:12
  • @curiousguy - Agree; my point is radio less secure than other physical media. But I think Iszi statements about "from security standpoint, wired preferred over wifi when mobility is not issue" was fair. Wifi makes it trivial for anyone nearby to eavesdrop or interfere and only starts to be comparable in security when you have add in strong encryption layers implemented in a secure method (which is non-trivial to do as seen from flaws in WEP/WPA/WPA2). Granted eavesdropping on a wired connection is possible as well, but requires getting to the actual cabling/routers and altering somehow. – dr jimbob May 14 '12 at 17:56
  • @drjimbob "_Wifi makes it trivial for anyone nearby to eavesdrop or interfere_" Obviously, "open" (cleartext) Wifi is trivial to attack for anyone in range. "_and only starts to be comparable in security_" Which "security" properties? As you said, encrypted Wifi is still detectable and can easily be jammed (and some people even say it gives you cancer!). It all depends on the security properties you need. I am happy to let my neighbours know I use Wifi, and they never tried to jam my signal (my MW oven tried to jam my Wifi, but then changed channels). – curiousguy May 14 '12 at 20:18
  • This is getting repetitive. I think the original statement was fair; when you don't care about mobility and everything else being equal its much safer to go with a ethernet cable (also can be much faster). Most wifi setups do not use RADIUS authentication servers, instead opting for (often-weak) pre-shared keys that allow eavesdropping by others which most modern networks with a star based topology would not allow (unless you control/attack the router; though these attacks similarly could be done on even if the first hop is through a wifi router). – dr jimbob May 14 '12 at 22:08
  • @drjimbob "_eavesdropping by others which most modern networks with a star based topology would not allow_" unless by "most modern networks with a star based topology" you mean "switched Ethernet with specific security features that prevent DOS on the switching logic as well as ARP poisoning", this is not true. "_Most wifi setups do not use RADIUS authentication servers, instead opting for (often-weak) pre-shared keys_" If they buy such professional-grade Ethernet switch, why do they use WPA-**Personal** with a weak passphrase? It is hard to believe that they fear wired more than wireless. – curiousguy May 16 '12 at 07:07
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From http://www.airtightnetworks.com/WPA2-Hole196 :

WPA2 Hole196 Vulnerability - FAQs

Then in what way can an insider exploit the Hole196 vulnerability?

(...) the attacker can decrypt the traffic (including login credentials, emails and other sensitive data).

This is a big joke, am I correct?

I mean, you fear internal attack, and don't at least encrypt login credentials???

This story is a PR stunt.

Rory Alsop
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curiousguy
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    Please explain the downvote. – curiousguy May 14 '12 at 16:47
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    Didn't down vote this and agree login credentials should be encrypted (e.g., https connection). But this allows a MITM attack; where you can trick a less-savvy, non-careful user to go to an attacker-controlled http site (that's otherwise similar to the real site) rather than an https site whether the login credentials are not encrypted and are intercepted. – dr jimbob May 14 '12 at 16:56
  • @drjimbob Indeed. You should always go directly to the https URL. You should bookmark this URL, not the HTTP URL. The HTTP URL should immediately redirect to the HTTPS URL, so people don't have a chance to bookmark it. You can also define as HTTPS-only with a header whose spelling I forgot. Anyway **I do not think that the Web browser should be used for anything really sensitive** unless it is totally castrated to only be able to access a few trusted servers. – curiousguy May 14 '12 at 17:19