How To Clean Malware from an Unbootable or Unusable System


malware cleanup-featurePrograms such as Malwarebytes Anti-Malware free are all well and good for cleaning malware infections provided you can access and use the operating system, but what about a machine which is so heavily infected the operating system won’t load or, if it does, is not responsive or functional? That’s where the bootable malware removal tools provided by most reputable antivirus vendors come into their own.

My youngest son recently brought over his aging laptop which he informed me was running like a hairy goat (that’s bad by the way). I pressed the go button and the operating system appeared to load okay but then, sure enough, I soon discovered that the system was near enough to unusable. Couldn’t open any programs, command prompt or run. Couldn’t open any directories, Computer or Control Panel. Right click functions weren’t working at all and only the occasional left click function – it was a mess.

Apart from almost everything being inaccessible, I noticed that the hard drive activity light was constantly blinking furiously. I also noticed that his resident antivirus program was not running. All symptomatic of a seriously infected machine. So, this really left me with only two viable options:

  1. A fresh install
  2. Try to cleanup the malware and, hopefully, return the system to its former glory.

Option #1 was problematic in this case. I won’t bore you with the details, suffice to say that this machine started off life running Vista and had been upgraded to Windows 7 at some time along the way. Minus any Vista installation media, and with the system almost totally unresponsive and no Windows 7 product key to hand, this approach moved quickly from optional more toward improbable.

So, it was on to option #2.

Best Free Bootable Malware Cleanup Tools

There are quite a few free bootable malware cleanup tools available but, in no particular order, I would recommend the following four:


I opted for Kaspersky Rescue Disk 10, mainly because I’d used it before with some success and was familiar with the program, but also because it is the smallest of the downloads (not sure why such a disparity in download sizes).

kaspersky rescue disk 10 - box

Most of these tools include an option to create a bootable USB flash drive as well as CD but I’m concentrating on the bootable CD option here. The first thing you need to do is burn the downloaded ISO to CD. This function is built into all Windows versions since Windows 7. In Windows 8.1 and 10, simply right click the ISO file and select “Burn disc image”. I suggest you also enable the option to Verify. For Windows 7, follow the instructions from Microsoft here: Burn a CD or DVD from an ISO file – Applies to Windows 7.

Now you’ll need to restart the machine and boot from the CD – you may need to change the device boot order in BIOS so the CD/DVD drive is number 1. This process may differ slightly between various BIOS editions but will be similar in most cases. Just Google around for instructions.

Working with Kaspersky Rescue Disk is pretty straightforward, the essential steps are:

  • Select Graphic Mode at the top of the list of options (should be enabled by default)
  • Wait while the program mounts the drive
  • Once that has completed (generally only a matter of 20-30 seconds) and the Scan window opens – make sure to click the My Update Center option first and download the latest definitions.
  • Once that has completed, go back to the Objects Scan window and start the scan.
  • You can view a more comprehensive guide here: http://support.kaspersky.com/8097

By the way; the scan is pretty intensive so be prepared for a long wait, in the case of my son’s laptop it took a little over 3 hours to complete.


Kaspersky-Rescue-Disk_10

There’s no real need to mess with the settings, everything is set to optimum/recommended by default. At the completion of the scan, if any malware has been detected, you’ll be presented with options on how to deal with it. Once again, the recommended action is clearly indicated and generally the best option.

That’s pretty much all there is to it and, at the end, hopefully you’ll be back with a malware free and fully operational system. In the case of my son’s laptop, it worked a treat, cleaned up multiple serious infections and everything is back to normal. Although, now I have regained full access, I noticed his system drive has 13GB free space out of a total 116GB, so more work to do yet. It is actually a 250GB hard drive separated into 2 partitions – the almost full 116GB system partition and a completely empty 104GB data partition, just goes to show how computer savvy my lad is, not!

I’ll move all personal data over to the empty data partition and then use PrivaZer to perform a thorough cleanup of the system drive. Should be running like brand new when he gets it back. Good ole dad!

 

About the Author

Jim Hillier

Jim is the resident freeware aficionado at DCT. A computer veteran with 30+ years experience who first started writing about computers and tech back in the days when freeware was actually free. His first computer was a TRS-80 in the 1980s, he progressed through the Commodore series of computers before moving to PCs in the 1990s. Now retired (aka an old geezer), Jim retains his passion for all things tech and still enjoys building and repairing computers for a select clientele... as well as writing for DCT, of course.

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