Another computer threat is now roaming around and ready to attack you at your most vulnerable state. Beware of Kneber Botnet!

NetWitness, based in Herndon, Va., said it discovered the botnet last month during a routine deployment of its monitoring software. It investigated further and discovered “an extensive compromise of commercial and government systems that included 68,000 corporate login credentials, access to email systems, online banking sites, Facebook,Yahoo (NSDQ: YHOO), Hotmail and other social networking credentials, 2,000 SSL certificate files, and dossier-level data sets on individuals including complete dumps of entire identities from victim machines,” the company said in a statement.

NetWitness said the attacks have been going on for about 18 months and appeared to originate in Europe and China. The company has shared its findings with the targeted companies and government agencies.

The company did not publicly identify the companies and government agencies with infected systems. A story in The Wall Street Journal said pharmaceutical maker Merck & Co. and Cardinal Health Inc. were among the companies with infected IT systems and those companies had contained the problem.

“Systems compromised by this Kneber Botnet provide the attackers with not only user credentials and confidential information, but remote access inside the compromised networks,” NetWitness CEO Amit Yoran said in the statement.

“These large-scale compromises of enterprise networks have reached epidemic levels. Cyber criminal elements, like the Kneber crew, quietly and diligently target and compromise thousands of government and commercial organizations across the globe,” Yoran said.