Security researchers at Herndon, Va.-based NetWitness Corp. have unearthed a massive botnet breaching almost 75,000 computers at 2,500 companies and Government agencies globally.

The latest virus, known as "Kneber botnet", named for the username linking the affected machines worldwide, gathers login credentials to online financial systems, social networking sites and email systems from infested computers and transfers the information back to hackers, NetWitness posted in a statement.

"Disturbingly, the data was only a one-month snapshot of data from a campaign that has been in operation for more than a year", NetWitness said in a statement announcing the discovery of the botnet late yesterday.

A 75GB cache of data is reported to have been stolen, was discovered by NetWitness included 68,000 corporate login credentials, login data for user accounts at Facebook, Yahoo and Hotmail, 2,000 SSL certificate files and a large amount of highly detailed "dossier-level" identity information.

In addition, the virus also granted attackers the remote access inside the compromised network, the company revealed.

More than 50% of the attacked systems in the Kneber botnet also possessed the competing Waledac Trojan, as those behind the attacks wanted to initiate some redundancy into their attacks.