Adrian Sampson/Flickr (CC)

Victims of the ongoing Petya cyberattack have paid £7,064 ($9,000) in Bitcoin to hackers so far to try and get their files back — but they won't have much luck.

The cyberattack broke out on Tuesday, impacting the Ukrainian government and banks, then spreading to a Russian oil company, advertising firm WPP, and other companies around the world. The attack takes the form of ransomware, malicious software that encrypts a user's files, then demands a payment in Bitcoin in exchange for decryption.

Victims posted screenshots of messages showing up on their computer screens, instructing them to send $300 worth of Bitcoin to a Bitcoin wallet address. They were also told to send their own Bitcoin wallet ID and "personal installation key", a unique identifier generated by the ransomware, to a dedicated email address.

According to Blockchain.info, which shows Bitcoin transaction data, there have been 36 payments to that Bitcoin address to date.

But the operator behind that email address, German firm Posteo, swiftly blocked access to that mailbox. The company said on Tuesday that people couldn't email the address, nor could hackers access it. That means hackers can't check who has paid them, nor can they release the key needed to decrypt a specific victim's files.

In short: Anyone who has paid the ransom is out of luck.