Thomas Roth says it is quite easy to break weak passwords using brute force methods with access to Amazon's cloud-based computing service, which is capable of testing 400,000 potential passwords every second. Amazon rents its service to customers for 28 cents per minute.
Networks that use the WPA-PSK setup to secure their networks are always going to be vulnerable to weak passwords (or more accurately, the pre-shared key). Short and weak passwords would be vulnerable to a brute force attack, especially at the speeds offered by Amazon's services.
"Nothing in this researcher's work is predicated on the use of Amazon EC2. As researchers often do, he used EC2 as a tool to show how the security of some network configurations can be improved," said Amazon spokesman Drew Herdener.
"Testing is an excellent use of AWS, however, it is a violation of our acceptable use policy to use our services to compromise the security of a network without authorization."
Roth claims to have found the key for a network in his neighborhood using his method and Amazon's service. The brute force attack took about 20 minutes to get the correct key, but Roth is making changes to his code which he reckons could bring the time down in such a case to about 6 minutes.
Roth will distribute his software publicly and give demonstrations on using it at the Black Hat conference in Washington D.C. He is releasing it to convince skeptical network administrators that nowadays, these such a attacks will often be successful against protected networks.
Of course, using a long and complex key to protect a network will make this method next to useless, even at 400,000 attempts per second.
Written by: James Delahunty @ 11 Jan 2011 2:09
