Synology DiskStation Manager (DSM), the company's in-house NAS operating system, is vulnerable to a CryptoLocker hack, which the company is referring to as "SynoLocker." The nature of how NAS units get infected by this hack is unknown, but when it is, the malware encrypts portion of data stored on your NAS volumes, and holds it for ransom, for 0.6 BTC (US $350 as of now). It decrypts that data only upon payment of that money. There's no guarantee of your data being held for ransom again. The issue is currently localized to NAS units running non-updated versions of DSM 4.3, but Synology is investigating if the hack works on DSM 5.0 as well.

Synology is urging users to take the following steps - close all ports for external (Internet) access, and unplug your NAS from your local network; and with your NAS plugged into just one machine, update DSM to the latest version; and back-up your data. If your NAS unit is infected, disconnect it from the network, perform a hard-shutdown, and contact Synology. The issue highlights one of the many dangers of a distributed currency, in which the beneficiary of funds is difficult to trace.

Here's an emergency statement from Synology (the company is preparing a press-release):

You may have heard by now that DSM is undergoing a CryptoLocker hack called SynoLocker - as of yesterday (08/03/14). It's a BitCoin Mining hack that encrypts portions of data, and ransoms the decryption key for .6 BitCoin ($350). So far, it looks like the matter is localized to non-updated versions of DSM 4.3, but we are actively working on, and researching the issue to see if it also effects DSM 5.0 as well.

In the interim, we are asking people to take the following precautions:

A. Close all open ports for external access as soon as possible, and/or unplug your Disk/RackStation from your router
B. Update DSM to the latest version
C. Backup your data as soon as possible
D. Synology will provide further information as soon as it is available.

If your NAS has been infected:
A. Do not trust/ignore any email from unauthorized/non-genuine Synology email. Synology email always has the "synology.com" address suffix.
B. Do a hard shutdown of your Disk/RackStation to prevent any further issues. This entails a long-press of your unit's power button, until a long beep has been heard. The unit will shut itself down safely from that point.
C. Contact Synology Support as soon as possible at, www.synology.com/en-global/support/knowledge_base