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In situations where the PC has no CD drive and operating a guest account with limited privileges, how to install an anti-virus tool? Malware is not permitting to open any anti-virus vendor's site and also blocking all sites opened via Google that contain the term "online scan".

I somehow managed to download through mirror links with a Download Manager as the browser's download was blocked by the malware. But the problem didn't end there. After I downloaded the anti-virus tool, it failed to install because it needed administrative rights. The user didn't know the administrator password.

I tried via command line with runas, but it also asks for the administrator password. The OS is Windows XP.

How to deal with these type of malwares if there is a scenario that CD drive is not there only Internet is there?

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reset admin password booting from usb...problem solved. – RobotHumans Dec 30 '10 at 17:24

Long story short, you cannot use a guest account for that, best solution is use a USB dvd drive, boot from a Kaspersky rescue disk to clean the PC of malware.

Or remove the hard drive and connect it to another PC using a USB adapter, clean it that way.

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+1 for live cd. The safest way is with a live cd. I don't think mounting the drive on another computer is a good idea because one might accidentally copy the malware to the host machine. – horatio Dec 30 '10 at 17:27
i keep a deepfreeze or similar pc around for that reason – RobotHumans Dec 30 '10 at 17:39
@horatio, been doing this for 10 years and has never happened, malwware does not magically jump from a mounted drive to the host OS, of course I always disable autorun on all my PCs. – Moab Dec 30 '10 at 18:05
I don't believe in magic, but I do believe in user-initiated activity :P. (e.g. "accidentally copy"). I wasn't even thinking of auto-runs. I know someone who backed up their data, reinstalled, and re-copied the malware back onto their computer. Stranger things have happened :) – horatio Dec 30 '10 at 18:44
@horatio, I must admit I always think people are smarter than they are. ;-) – Moab Dec 30 '10 at 19:36

First clean your computer with a live usb based antivirus program (try ClamAV on a live usb stick). Then use the Offline NT Password & Registry Editor to reset the administrator password. Log into Windows as an administrator, and install a real antivirus solution (MSE recommended).

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