Bitcoin Extortion Plot Targets Pizza Restaurants
Businesses are being served with 'notice of extortion' letters demanding bitcoins to avoid negative online reviews.
A number of US pizza restaurants have reported receiving the printed letters, which include a number of threats for non-payment of the demand.
As well as negative reviews on Yelp.com, the culprit threatens to carry out denial of service attacks on telephone lines and cause mercury contamination of food.
The letter reads: "Because many of the actions we take are catastrophic and irreversible, it is advised (to) pay ... before the deadline is reached."
Some of the threats were posted by business owners to the website Reddit.
Users suggested the attackers could be traced using a technique which makes it possible to identify the make and model of printer used to create the document.
The letters demand payment of one bitcoin, worth £339, within a month, after which the demand rises to three bitcoins.
In Grand Rapids, Michigan, pizza store owner Mike Raymond received a letter but refused to pay up.
He said: "At first, I'm looking at it and I'm thinking, 'Oh, it's one of my friends playing a joke on me.'"
When he realised it was a real threat, he decided not to pay.
"There are food costs and finance, labour and the rising cost of gas," he said.
"Do you really need to have somebody now threatening you with extortion?
"They're taking your lunch money and we're not going to let them."