John Scott-Railton and Bill Marczak, senior researchers at the Citizen Lab, an interdisciplinary laboratory based at the University of Toronto in Canada, made a two-hour appearance on Monday before the Polish Senate’s seven-member panel probing spyware use, Poland's PAP news agency reported.
The hearing took place after the Citizen Lab reported in December that Brejza as well as prominent Polish lawyer and former Deputy Prime Minister Roman Giertych and prosecutor Ewa Wrzosek had been hacked with powerful Pegasus spyware produced by Israel’s NSO Group.
Speaking via video link on Monday, the cybersecurity experts said they were in possession of forensic evidence that data had been stolen from Brejza's phone, the PAP news agency reported.
The stolen data was linked to important moments in political life, they claimed, but have been unable to identify who was behind the hacks.
Scott-Railton told the hearing panel that he and other Citizen Lab researchers were convinced the Polish senator had been extensively monitored.
The experts said they first identified Pegasus activity in Poland in November 2017.
The Senate inquiry was set up following reports by the Associated Press news agency that in 2019 Brejza, a senior politician with Poland's opposition Civic Platform (PO) party, was hacked with Pegasus spyware.
According to the Citizen Lab, which researches digital surveillance, Brejza’s phone was digitally broken into 33 times between April and October 2019 when he ran his party’s parliamentary election campaign, the AP has reported.
Citizen Lab researchers earlier said that Giertych and Wrzosek had also been put on surveillance with NSO software.
Bosacki, a former journalist and ex-ambassador to Canada who leads the opposition Civic Coalition grouping in the Senate, told reporters last week that the special panel would seek to analyse "instances of illegal Pegasus-aided surveillance" and related breaches of law.
The inquiry aims to assess the impact of any such breaches on the electoral process, he said, adding that the committee would work to draw up and submit a bill to reform Poland’s security services.
Earlier last week, Poland's conservative leader Jarosław Kaczyński, a deputy prime minister, was quoted as saying in a media interview that the creation and use of Pegasus reflected “technological change, such as the rise of encrypted messaging applications” and added that “it would be bad if Polish authorities did not possess this type of tool.”
At the same time, Kaczyński, who heads Poland's governing Law and Justice party, said that Pegasus had not been used against the opposition, calling such claims “utter nonsense.”
In late December, Polish Prime Minister Mateusz Morawiecki dismissed accusations by the opposition over Pegasus, warning against "a spiral of fake news."
Meanwhile, Stanisław Żaryn, spokesman for Poland’s security services, said after the launch of the Senate inquiry last week that in Poland "parliamentary oversight of security sector agencies is exercised by a designated lower-house committee that also includes opposition politicians."
Under Polish parliamentary rules, Senate committees lack formal investigative powers, unlike special inquiries set up by lawmakers in the lower house, the PAP news agency reported.