Hundreds of confidential NATO documents sent to Portugal were stolen and being sold on the dark web, leading Portuguese daily Diario de Noticias reported on Thursday.
Anonymous sources told the newspaper that Portugal’s highest military body, the EMGFA, was the target of a “prolonged and unprecedented cyberattack” that resulted in the secret NATO information being leaked.
The Portuguese government only found out about the cyberattack in August after American intelligence officials discovered the classified documents were for sale on the dark web, according to the report.
Sources said that the leak is considered “extremely serious.”
Diario de Noticias contacted the US Embassy in Lisbon and several Portuguese government bodies to comment on the case. None of them were willing to confirm or deny the report.
“The government can guarantee that Portugal’s Defense Ministry and armed forces work daily to ensure that Portugal’s credibility, as a founding member of NATO, remains intact,” said a spokesperson from the prime minister’s office.
“Whenever there is a suspicion of a compromised cybersecurity network … the situation is extensively analyzed, and all the procedures are implemented,” the statement continued.
The first investigation of the data leak discovered that security rules for classified information had been broken, as non-secure connections were used to receive and forward the documents, sources told Diario de Noticias.
The cyberattack was reportedly undetectable and committed by a bot network designed to detect classified information.
NATO has allegedly demanded explanations from the Portuguese government. According to the report, two Portuguese officials will go to the NATO headquarters in Brussels for a high-level meeting next week.
This would not be the first time Portugal was involved in a security breach related to NATO documents. In 2018, Portuguese intelligence officer Frederico Carvalhao Gil was convicted for spying for Russia after he was found selling classified NATO and EU documents to a Russian agent.