Can you believe that a Microsoft representative actually said were getting to the point where its not worth cleaning up malware-infected systems? The hand-wringing was so extreme the whole industry has blisters! Surely this shows how far weve sunk, or its an admission of failure by Microsoft or some such dramatic thing, right?
Personally, I saw it as an acknowledgement of what reasonable people have known for years. Cleaning up malware has always been a major feature of anti-virus software, but its become increasingly undesirable (Ill stop short of “useless”). There are better options, as Mike Danseglio, a program manager in Microsofts Security Solutions group, said. The solutions are out there for enterprises. The goal should be to make them reasonably available to consumers and small businesses.
Even the anti-virus guys agree with Danseglio, at least in private. I asked a couple of anti-virus industry people and they said that of course its more desirable to re-image a system. The advantages are huge.
- Theres a very high likelihood of success with re-imaging. There are theoretical ways for an attack to slip past a re-imaging, but theyre highly unlikely and most of them, such as EFI-based attacks, can be dealt with through thorough procedure.
- There are many good systems available at an enterprise level for managing system images, including tools that come with Windows. If you manage them correctly, recovering a system image can be relatively quick and easy.
- Good management practices dictate a system in which all data and user customizations are stored in the profile on the server. Being able to swap in a new image with ease is one of the benefits of following this good practice.
- System cleanups can have adverse consequences, breaking applications in some cases. Even where they appear to succeed, the cleaned-up system can not be trusted as it was before infection.
- Cleanup can be a long and complicated process, often involving much expert time. Re-imaging, when set up properly, can be a relatively automatic procedure performed without any complicated decision making.
Im sure most enterprises dont actually live in the neat-and-clean world of best-practices that Ive described, but they know its what they should strive for. They also know, or should know, that cleanup is a sub-optimal process.
Home Users Have It
But for home users and small businesses, things are harder. Its not practical, for reasons of cost and expertise, for them to set up a robust imaging system. As a result, as with so many other areas of computing, theyre stuck with the sub-optimal solutions.
Even if they spent the money for the network hardware, home users couldnt really do images the way enterprises do. The right way is to use a base install image, in combination with necessary device drivers and a tool named sysprep, to effectively automate an installation of the operating system along with needed applications and other files. This is out of any home users or small business league.
What they can do is use a tool like Norton Ghost and cheap external storage to store a known good image of an installed system. A huge external USB hard drive can be purchased for as little as $100 and, with Ghost set to re-image periodically, provides the most practical backup system around. Periodically it might make sense to burn an image to a CD-R or DVD-R.
Restoring an image from such a setup involves booting off the Ghost CD and restoring the most recent image known to be safe. This can be a difficult decision of course, but theres no way around it. If you go back to an old burned image, you might lose documents.
Im not sure what the best way to solve the home user issue is, but it needs to be solved. In an era of rootkits, you just cant trust cleanups. Probably some variation of the Ghost and external drive I mentioned is the best choice, although it is a complicated option. It also has the advantage of being a real backup solution, with access to individual files if necessary.
Another option for home users is System Restore, which takes a snapshot of the operating system and user customizations periodically and at important events, like application installs. Unfortunately, its not completely trustworthy; its possible for malware to mess directly with the backups, and it doesnt clean up some areas of the system, like the inbox.
Rootkits have been around a long time and affected UNIX long before they affected Windows. I dont blame Microsoft for malware that ruins a system to the point that its hard to clean up reliably. Any badly administered system can be put in the same position.
If I blame Microsoft for anything, its for focusing most of its solutions in this area on the enterprise.
Security Center Editor Larry Seltzer has worked in and written about the computer industry since 1983.
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