Recently, a type of malware called ransomware has begun to appear more frequently. Its purpose is to effectively take data hostage and demand a ransom in exchange for returning it. CryptoLocker, for example, does this by encrypting all document files on a computer and mapped network drives, then requiring a payment of roughly $300. Upon confirmation that the payment has been received, the decryption key is then sent to the victim. In some cases, of course, the decryption key may not be sent even if payment is made.
Naked Security has an article about the recent appearance of “Koler,” a variation of ransomware that issues a fake “police warning” and demanding payment of a fine, again about $300. This malware does not, however, encrypt data. It is also fairly straightforward to protect against, as the Android setting “Allow installation of apps from unknown sources” must be enabled for it to infect a device.