A huge weekend spam campaign exploited Verizon Wireless and spread the Zeus/ZBot Trojan. Security experts said the attack started on Friday morning with 200,000 malicious messages an hour being sent. The spam messages claimed to be from Verizon Wireless and told customers they had exceeded their credit limit and to check their accounts via the attached “tool”.

When the attachment was downloaded it installed the Zeus Trojan, notorious for stealing personal and banking info. The Trojan install a keylogger which is activated whenever a banking or financial site is visited and logged into. It also steals login info from popular sites like Amazon, MySpace, Facebook and Ebay. Verizon Wireless released a statement saying they are aware of the incident.

          We’re aware of this spam/phishing message being sent to our customers over the past several days, and have taken steps to stop it from occurring,” said a Verizon spokesperson.

The campaign sent over 9 million messages before abruptly shutting down Monday morning. The researchers say the Trojan was repackaged six different time in an effort to evade detection by anti-virus software and firewalls.

Zeus has been around for quite awhile now. Its past spam campaigns included faked password reset requests from MySpace, faked notifications from the IRS, and a fake update from Microsoft.