The Crisis virus poses no real danger for virtual machines, but the malware does presage a likely move by criminals and attackers toward finding better ways of infecting virtualized servers and infrastructure, security experts said this week.
While Crisis can infect Windows machines and spread from there to VMWare virtual machines and Macs, the software has not been used in any real attack and is unlikely to affect many VMWare customers, Warren Wu, director of the data center business unit at security software firm Trend Micro, stated in an Aug. 23 blog post.
However, the move suggests that attackers see benefits in infecting virtual machines, and with an increasing amount of important data hosted on VMs, criminals will likely seek out the systems in the future, he said.
"You don't have to go looking for Crisis on your data center VMs, because it's not really targeted at that," he said in an interview Aug. 24. "But a future malware author could have an 'Aha!' moment and decide to use the same technique to get access to the VMs in the data center."
Security firms published an analysis of Crisis in July focusing on the malware's ability to infect Mac OS X machines. Earlier this week, however, Symantec analyzed another aspect of the malware: Its ability to infect VMWare virtual machines running on Windows. While antivirus firms have yet to find the malicious software in the wild, the program performs its intended tasks quite well, Vikram Thakur, principal security response manager for Symantec said Aug. 22.
"I would actually consider this beyond a proof-of-concept [program]," he said. "It is probably being installed on computers that we have no visibility into."
On any machine-including virtual machines-infected by Crisis, the malicious software would act as a backdoor, eavesdropping on communications and sending out information to a command-and-control server on the Internet, according to the Symantec analysis.
Yet data centers using virtual infrastructure do not need to worry, because Crisis only affects virtual machines running on top of the Windows operating system, said Trend Micro's Wu.
Virtual machines are classified into two categories: Type 1 virtual machines essentially run their hypervisor-the software that emulates a standard server or computer-on top of the hardware, while Type 2 virtual machines run in a hypervisor that runs on top of the operating system. The vast majority of virtual machines are Type 1 VMs running in a data center, where an intermediate operating system is not necessary, Wu said.
While security researchers have warned about the potential for disruption if attackers ever found a way to take control of a hypervisor, few attacks have materialized. In 2006, Joanna Rutkowska, a malware researcher at Singapore-based IT security firm COSEINC, built a prototype of an attack on the hypervisor known as "Blue Pill."
Since then, however, attacks on the hypervisor have largely failed because VMWare and other developers have effectively minimized the attack surface area of the software. With the addition of new features to hypervisors and the lure of more valuable data managed by systems running on virtual infrastructure, many security experts have warned that a breach of such systems will likely come sooner, rather than later.
Data center IT managers should adopt a defense-in-depth strategy to foil malware that targets their virtual systems. Of course, Trend Micro, a seller of antivirus, recommends that companies install such anti-malware technology on every virtual machine. However, Wu also recommends that companies minimize the number of administrators with access to data center systems to reduce the chance that an infection could spread from their systems to the data center.
"Crisis infects virtual machines like macro viruses infected Word documents," he said. "To protect against that, companies should make sure that they restrict access to their repositories of virtual machines."