|This is an example of ransomware from wired.com. This is not the Department of Justice as the screen might indicate, but rather some blackhat who has infiltrated your system and is looking for a easy cash grab.|
This is what happened to the Los Angeles Hollywood Presbyterian Medical Center. The entire network was shut down and access would only be granted if they paid a ransom of $3.6 million.
You can see how ransomware has the potential to wreak havoc for anyone whose livelihood relies on a computer. It's a malware that encrypts files and requires a key to unlock. It can come into a network through a simple file attachment in an email.
Do not respond to the demands of these cyber hacks. First check out reputable sites, like your Google FAQs, PC World, and perhaps first: your antivirus company, such as Vipre, Norton, or McAfee, to see what types of patches they have to remove this Trojan horse.
Most viruses hold your devices hostage but ransomware ups the ante with a payment demand. Now, just like a real-life kidnapping, paying the ransom doesn't mean the hacker will release your computer.
The best prevention is to play safe online. Top up your protection software and make sure it's current. Look at the link of a website before you click it to make sure it matches what you're expecting. For example, if you receive an email from Amazon advertising a product that interests you, when you mouse over the link in the email, you can see what link highlights before you click in most cases. But to be safe, go to the top of the browser and log directly into the account and search for the product. Don't open unexpected attachments unless there is an explanation from a known sender or if the email looks suspicious (even from a known sender.) Ask the known sender if they sent you a file out of the blue. When in doubt, don't open the attachment.