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 antivirus 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 $90 and $305 for each record lost, who can afford to turn a blind eye to what may invisibly be leaching sensitive data from their network?

The rise of rootkits
Rootkits date back to the earliest years of the Internet, when crackers created cloaked variants of Unix commands to ensure their deeds on compromised systems would go undetected. A concern mainly of system administrators for Net-connected Unix systems, rootkits remained relatively low-profile for many years, until Sony BMG Music Entertainment's Windows rootkit digital rights management (DRM) boondoggle of 2005.

In an attempt to enforce copyright protection, Sony BMG developed a rootkit that surreptitiously installed extended copy protection (XCP) or MediaMax CD-3 software when music CDs were played on a PC. Poorly designed, the software opened holes in the Windows OS, facilitating infection by viruses and causing other system problems. Mark Russinovich, now a technical fellow at Microsoft, discovered the rootkit's behavior, which he then announced on his blog. The resulting furor and further illustrations of the fallout of the rootkit led Sony BMG to recall the CDs and issue a removal program. Unfortunately, the removal program was equally poorly designed, leading to additional privacy and security concerns, as documented by Russinovich.