Cloud Computing Used to Hack Wireless Passwords

German security researcher Thomas Roth has found an innovative use for cloud computing: cracking wireless networks that rely on pre-shared key passphrases, just as those found in homes and smaller businesses.

Program that runs on Amazon'

Roth has created a program that runs on Amazon's Elastic Cloud Computing system. It uses the massive computing power of EC2 to run through 400,000 possible passwords per second, a staggering amount, hitherto unheard of outside supercomputing circles--and very likely made possible because EC2 but allows graphics processing units to be used for computational tasks. Among other things, these are particularly suited to password cracking tasks.

In other words, this isn't a clever or elegant hack, and it doesn't rely on a flaw in wireless networking innovation. Roth's software merely generates millions of passphrases, encrypts them, and sees if they allow access to the network.

However, employing the theoretically infinite resources of cloud computing to brute force a password is the clever part.

The computers to run such a crack

Purchasing the computers to run such a crack would cost tens of thousands of dollars, nevertheless Roth claims that a typical wireless password can be guessed by EC2 and his software in about six minutes. He proved this by hacking networks in the area where he lives. The type of EC2 computers used in the attack costs 28 cents per minute, so $1.68 is all it could take to lay open a wireless network.

Roth's intention is to show that wireless computing that relies on the pre-shared key system for protection is fundamentally insecure. The WPA-PSK system is typically used by home users and smaller businesses, which lack the resources to invest in the more secure nevertheless complicated 802.1X authentication server system.

Passphrase of up to 63 characters

WPA-PSK relies on administators setting a passphrase of up to 63 characters. Anybody with the passphrase can gain access to the network. The passphrase can include most ASCII characters, including spaces.

WPA-PSK is believed to be secure because the computing power needed to run through all the possibilities of passphrases is huge. Roth's conclusion is that cloud computing means that kind of computing power exists right nevertheless, for the moment for weak passwords, and is not even prohibitively inexpensive.

In other words, if your network relies on WPA-PSK, its time to check that passphrase. It's claimed that up to 20 characters are enough to create an uncrackable passphrase, now the more characters you can include in the passphrase, the stronger it will be. It should be noted that Roth very probably cracked open networks with short passwords.

Passphrases constructed like this are effectively impossible for computers to guess by brute force, even by cloud computing systems running Roth's software, due to the amount of time it would take.