Hackers stole thousands of Bulgarians' personal financial data and distributed it from a Russian-based email in an attack possibly related to the purchase of new F-16 fighter jets from the United States, the government said on Tuesday.
The hackers accessed the National Revenue Agency's (NRA) systems on Monday before sending local media confidential information purportedly from Finance Ministry servers, Interior Minister Mladen Marinov said.
"Maybe this is the first case in Bulgaria which is successful and a lot of personal data has been stolen," Marinov told local TV channel.
He said the cyber attack was probably motivated by Bulgaria's move to buy eight new Lockheed Martin F-16 fighters for $1.256 billion from the United States, its biggest military purchase since the end of communism.
A political analysis can also be made — the email comes from a Russian site... and a crucial decision to buy the F-16s aircraft was made yesterday," Marinov said.
Once an obedient satellite of Russia, the Balkan nation has joined the European Union and trans-atlantic NATO alliance in the last decade and is replacing its aging Soviet made MiG-29 planes with the F-16s.
A leading Bulgarian newspaper, 24 Chasa, said one file emailed by the hackers had more than 1.1 million identification numbers with income, social security and healthcare figures.
According to local web site Mediapool, the email came from an address with Russian mail provider Yandex.
There was no immediate comment from authorities in Moscow.
Bulgarian media said the hackers' email included an appeal for the release of WikiLeaks founder Julian Assange. "Your government is mentally retarded. The state of your cyber-security is a parody," reports quoted it as saying.
In a statement, the NRA said it and security agencies were checking "a potential weakness" in its computer systems.