Have you been a victim for the new "Legal" threat there is circulating for some time now on the internet? I haven't heard of such thing before until one of my friends told me about it earlier today since he got it on his computer yesterday and so far I haven't got it yet (of course you can't be absolutely sure these days can you?). What he told me is indeed scary and that's about a new "legal" trojan called police.trojan aka ransomware by security experts and http://blog.perhellqvist.se/blog/2012/03/14/ny-elaking-laser-datorn-och-kraver-losensumma/ (sorry only a Swedish blog), which has some indications of where the trojan has its origin, but haven't been able to examine the trojan more intensively atm.

To make it simple... You're falsely accused for crimes you didn't commit and they have locked everything on your computer plus they demand you to pay penalty of 100 euro to unlock your computer and once they receive your money (some people are reporting that they pay 100 euro, but have their computer being unlocked hell no they haven't and are still locked) your computer will be unlocked, but in the mean time they steal every piece of information you have stored on your HDD. Your best bet to get rid of this trojan is to http://www.carl-berg.se/post/fighting-ransomware provided by another Swede since he also got this "legal" trojan into his computer and managed to get rid of it based of his computer knowledge. Information like http://www.deletevirus.net/polisen-enheten-for-databrott-ransomware-removal/ or http://trojan-killer.net/metropolitan-police-virus-warning-remove/ might be helpful too.

Those things have been around for a while haven't they? I know somebody who had a virus demanding euros from them, he was able to remove it though.

Just to be clear: this thing isn't from any police force. It's a con which tries to gain a (false) sense of legitimacy by pretending to be from police. Sending them money will (probably) do nothing for you, and serve only to profit the buggers behind it.

Police -or any government agency- are highly unlikely to take payments via Ukash or Paysafecard.

A quick Google on this one turned up https://community.mcafee.com/thread/45415 from McAfee with more info, along with a few others. It's not new. It made the jump to the U.S., UK and Canada all the way back in May, and is your typical "ransomware" virus, just with a slightly different spin with the faux police nonsense.

It's still basically just a trojan, however. Not some sort of super-virus that will magically transport itself onto your computer, then go on to beat you up, take your wallet, kick your puppies, etc. Use a good anti-virus, use NoScript and AdBlock, and don't go on sketchy websites without protection or download every attachment you get sent.

Also, as it's been around since at least 2011 from what I can see, I would imagine most AVs worth their salt have it in their databases and should be able to detect it.

In other news, security experts recommend not opening mysterious email attachments or visiting dodgy web sites. Film at 11.

So, they're basically holding your computer for ransom?

Holy run on sentence, Batman!

Yes they do I'm afraid.