Security firm Panda Labs claims boot sector viruses and rootkits are poised to make a comeback:
Panda's report does raise a new concern, though it comes from a surprising direction. According to the company, boot sector viruses loaded with rootkits are poised to make a comeback. This honestly sounds a bit odd, considering how long it has been since a boot virus has topped the malware charts, but it's at least theoretically possible. Such viruses have a simple method of operation. The virus copies itself into the Master Boot Record (MBR) of a hard drive, and rewrites the actual MBR data in a different section of the drive.
Once a rootkit is loaded into the MBR, it can use its position to obfuscate its own activity. This is obviously rather handy when attempting to hide from rootkit-detection software, and could cause a new set of headaches for antivirus software if the threat actually materializes. Panda Lab's report does a good job of explaining what a boot virus is and how it can infect a system, but it says virtually nothing about why such attack vectors are a concern today.
The problem with boot viruses is that their attack vector is fairly well-guarded. Any antivirus program worth beans will detect a suspicious attempt to modify the MBR and will alert the end user accordingly. Running as a user rather than an administrator should also prevent such modification even if you don't have an antivirus scanner installed. Panda implies that this kind of exploit could be an issue in Linux, and I suppose that's theoretically possible, but Linux always creates a user account without root access by default.