I’ve added a Flattr-account for Pyrit here.
The news report that London’s Heathrow airport ran out of toothbrushes and alcohol due to the numerous canceled flights and people sleeping at the airport. What a pity: If there are two things you need when sleeping with strangers it’s alcohol and a toothbrush.
Once I finally have time to care about Pyrit again, version 0.4 will get kicked out of the door. Once that is done, the first to-do is to remove the dependency on scapy. The library is mind boggling bloated, slow and buggy. Did I mention that it is *slow* and *buggy* and *bloated*? I hate it.
There is an interesting post on Pyrit’s mailing list about running Pyrit on Amazon’s EC2 cloud which now supports GPUs. One
million billion passwords go away for 7 hours of work and $14.7 in cash.
Today Slashdot cites a blog-post by Chester Wisniewski from Sophos Security Research about a proposal by Chester on how to make public, unencrypted WiFi-Hotspots more secure. With the release of Firesheep, it has become the task of clicking a button to steal authentication-cookies from unencrypted, captured network-traffic. Public, unencrypted WiFi-Hotspots are by definition the most vulnerable playground for that.
Chester proposes to use WPA/WPA2-PSK with a universal, non-secret password; for example “free”. He points out that an encrypted WiFi-network everyone knows the password for is better than a completely unencrypted network:
What is the value of a password if it is a “well-known secret?” WPA2 negotiates unique encryption keys with every computer that connects to it. This means you and I cannot spy on one another’s traffic even when sharing access on the same access point.
This is a golden opportunity for a high-profile provider of free WiFi to step up and show us how easy it is.
Join my movement to provide a safer internet for everyone by making sure you provide secure wireless access.
The argument is well-intended which however does not protect it from being completely false and misguiding due to a lack of understanding how WPA/WPA2-PSK works. The proposal boils down to security theatre where means are provided to make people feel safer while in fact they are not.
Chester argues that even if the password used for WPA/WPA2-PSK is known to all parties, WPA would “negotiate unique encryption key“, so one “cannot spy one another’s traffic“; this is only half-true. As I pointed out in The Twilight Of Wi-Fi Protected Access, the PSK-mode (“pre shared key”) of WPA/WPA2 is seriously flawed as it trades the one most important thing about secure communication – authenticity - to gain simplicity. In case of WPA/WPA2-PSK, authenticity is only provided through a single password that everbody uses. We can therefor only tell apart those that know the password from those that do not know the password. The identity of any party within such a network can’t be proven any further than that as everbody uses the same key to do so: The Pairwise Master Key, which derived from the password
As the Pairwise Master Key is not authentic to exactly one party, all session keys derived from it also can’t be. Therefor all traffic protected by the session keys can’t be authentic. However, there is no point in encryption in we do not know who we are encrypting to. In a WiFi-network protected by WPA/WPA2-PSK, every user who knows the password can pretend to be anyone (including the Access-Point) and inject, modify or drop any traffic owned by anyone else. The only promise that WPA/WPA2-PSK can make is to protect users within the network from those outside. The line of defense is drawn by knowledge of the password; beyond that, there is no security between users.
The proposal made by Chester is based on a false understanding about how WPA/WPA2-PSK works and what promises it can make. The intention to make the users of public WiFi-hotspots more secure creates the feeling of being more secure (“We do that for security. Therefor it makes us more secure.“). In that sense, Chester’s proposal is not only misled but dangerous.
One may argue that “some” security is better than no security. This however is as true as the hedge on the lawn in front of the bank adds to your money’s security and the people telling you “Of course your money is secure in our bank! Didn’t you see the hedge on the lawn outside?“
To underline my point, here are two ways on how to spy on any user within such a network:
Man in the middle:
In the end, I again quote from Chester’s proposal:
Join my movement to provide a safer internet for everyone by making sure you provide secure wireless access. If you care enough to provide networking to your friends, neighbors, or customers, help them enjoy it securely.
Join the movement. Do not provide WiFi protected by WPA/WPA2-PSK to your friends, neighbors, or customers. They can’t be trusted, they can’t trust you and they can’t trust each other. For all men are evil and will always act according to the wickedness of their spirits whenever the chance…
280.000 PMKs/s fly by in yet another video of yet another high-end system dedicated to some serious number-crunching.