With the nasty CryptoLocker malware making the rounds — encrypting its victims' files, and then refusing to provide the unlock key unless a payment of $300 is made via Bitcoin or a prepaid cash voucher — ransomware is back in the spotlight.
You can remove many ransomware viruses without losing your files, but with some variants that isn't the case. In the past I've discussed general steps for removing malware and viruses, but you need to apply some specific tips and tricks for ransomware. The process varies and depends on the type of invader. Some procedures involve a simple virus scan, while others require offline scans and advanced recovery of your files. I categorize ransomware into three varieties: scareware, lock-screen viruses, and the really nasty stuff.
The simplest type of ransomware, aka scareware, consists of bogus antivirus or clean-up tools that claim they've detected umpteen issues, and demand that you pay in order to fix them. Some specimens of this variety of ransomware may allow you to use your PC but bombard you with alerts and pop-ups, while others might prevent you from running any programs at all. Typically these invaders are the easiest type of ransomware to remove.
Next is the ransomware variety I call lock-screen viruses, which don't allow you to use your PC in any way. They display a full-size window after Windows starts up — usually with an FBI or Department of Justice logo — saying that you violated the law and that you must pay a fine.
The really nasty stuff
Encrypting malware — such as CryptoLocker — is the worst variant, because it encrypts and locks your personal files until you pay up. But even if you haven't backed up your files, you may have a chance to recover your data.
Before you can free your hostage PC, you have to eliminate the hostage taker.
If you have the simplest kind of ransomware, such as a fake antivirus program or a bogus clean-up tool, you can usually remove it by following the steps in my previous malware removal guide. This procedure includes entering Windows' Safe Mode and running an on-demand virus scanner such as Malwarebytes.
If the ransomware prevents you from entering Windows or running programs, as lock-screen viruses typically do, you can try to use System Restore to roll Windows back in time. Doing so doesn't affect your personal files, but it does return system files and programs to the state they were in at a certain time. The System Restore feature must be enabled beforehand; Windows enables it by default.
To try System Restore, shut down your PC and locate the F8 key on your PC's keyboard. Turn the PC on, and as soon as you see anything on the screen, press the F8 key repeatedly. This action should bring up the Advanced Boot Options menu; there, select Repair Your Computer and press Enter. Next you'll likely have to log on as a user; select your Windows account name. (If you don't have a password set, leave that blank.) Once logged on, you'll find shortcuts to a few tools; click SystemRestore.
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