Original URL: http://www.theregister.co.uk/2009/12/09/amazon_ec2_bot_control_channel/

Zeus bot found using Amazon's EC2 as C&C server

Clouds on Mount Olympus

By Dan Goodin

Posted in Security, 9th December 2009 19:53 GMT

Add Amazon's EC2 to the roster of cloud-based services being exploited to do the bidding of malware gangs.

Over the past few days, a new variant of the Zeus banking trojan has been spotted using the popular Amazon service as a command and control channel for infected machines. After marks get tricked into installing the password-logging malware, their machines began reporting to EC2 for new instructions and updates, according to researchers from CA's internet security business unit.

"We believe this was a legitimate service that was purchased and compromised via a vulnerability" such as a weak password, Don DeBolt, CA's director of threat research, told The Reg. "It could have been any vulnerable system on the internet."

Over the past few months, accounts on Twitter, Google's app engine, and Facebook have also been transformed into master control channels for machines under the spell of surreptitious malware. In addition to their high availability and low cost, the sites are attractive because they don't set off alarms when infected machines are observed connecting to them.

While it's relatively easy to block channels located in China or based on internet relay chat, blacklisting some of the world's most popular online destinations is another matter completely.

According to analysis from Zero Day blogger Dancho Danchev, the cybercriminals behind Zeus appear to have plugged into Amazon's Relational Database Service as a backend alternative in case they lose access to their original domain.

DeBolt said the EC2 channel was disconnected after it was brought to the attention of Amazon officials. People who want to report future abuse of cloud-based services offered by the online retailer can use this link. An Amazon spokeswoman didn't respond to an email requesting comment. ®