Late at night, a system administrator performed a routine check of a crashed server, one of 48 systems comprising a major online infrastructure that generated about US$4 million per month in revenue. He was a bit surprised that the system had gone down, as it had been humming for months without any indication of being prone to crashing. The check uncovered three encrypted files. The administrator called on MANDIANT to analyse them.

What MANDIANT found was that an unauthorized kernel modification had caused the system to become unstable, and that the modification had compromised the system's security as well. To determine the extent of the breach, each of the 48 servers needed to be taken offline, booted in a controlled environment, and analyzed for three to five hours each. About half had the crack installed, forcing the company to assume that all credit card information had been compromised. What had first seemed routine resulted in a financial nightmare -- one that many companies are leaving themselves exposed to, unaware of the increasing pervasiveness of rootkits.

Every organization is aware of the importance of securing core systems, networks, and end-user equipment in an increasingly mobile and malware-saturated world. But what most may not realize is the growing threat of malicious software intended to keep its presence hidden from administrators and traditional anti-virus software. Termed after early Unix packages designed to replace commands that would otherwise alert admins to the presence of intruders who had "root" or admin access to systems, rootkits are on the rise among those seeking to steal corporate and personal information for financial gain.

Rootkits alone, of course, are not inherently malicious. But when packaged with malware, they can facilitate deeply compromising security breaches undetected, especially as they become increasingly popular for attacks on non-Unix systems, specifically Windows. And with Forrester Research recently estimating that security breaches cost companies between US$90 and US$305 for each record lost, who can afford to turn a blind eye to what may invisibly be leaching sensitive data from their network?