The Clampi trojan botnet, revealed by SecureWorks' researchers this week at the Black Hat conference in Las Vegas, has infected as many as one million machines and is designed to steal login details at some 4,600 sites, such as banks, mortgage companies and other places to pay bills online.
What makes the malware so concerning to experts is that Clampi can spread faster than other modern-day data-stealing trojans, such as Zeus and Coreflood, said Joe Stewart, director of malware research at SecureWorks.
The trojan was written so that it tries running PSExec, a Microsoft tool to execute processes on remote Windows systems, anytime a user logs in to a Clampi-infected PC, Stewart told SCMagazineUS.com.
Specifically, Clampi -- which initially seeds computers through a drive-by web exploit -- is looking for a domain administrator who has permission to use PSExec to log in to that zombie machine, he said. If one does, Clampi can spread to all nodes on the network.
"That's what concerns us -- the increased usage of this technique," he said. "It could have a very large impact on the enterprise when all workstations come down with [Clampi]."
As a result of this tactic, administrators must not only ensure the PCs under their control are fully patched and running updated anti-virus solutions, but also that they themselves do not log in to potentially compromised computers, Stewart said.
Researchers at SecureWorks have been studying the trojan since 2007 but have had a difficult time learning much about it because of the way its code is packed.
"It's very difficult to get any information about it," Stewart said. "It's really slow going in reverse-engineering it."