OSLO, Norway -- One of the first times hackers tried to infiltrate Danny O'Brien through his email inbox, it was in the guise of a human-rights event invitation from what appeared to be a friend.
"It included a PDF, which, when clicked on, would log all your keystrokes, record audio, and download documents from your hard drive," said O'Brien, the international director of the Electronic Frontier Foundation, who has since found himself a repeat target of cyber attacks.
(He didn't click on it, luckily.)
Such "spear-phishing" attempts -- which take the form of an email from a hacker posing as an acquaintance -- are hardly rare among human-rights workers. Lobsang Sangay, the prime minister of Tibet, told an audience at the Oslo Freedom Forum last week that once, after arranging an interview with a Time journalist, he received a follow-up email with an attachment titled "interview questions."
He called the reporter, who said no email had ever been sent.
"The Chinese government tries to monitor me, destroy my computer, make my life difficult," Sangay said.
Spear-phishing attempts represent just one of the many kinds of cyber attacks that government agents are increasingly deploying in order to keep tabs on dissidents.
While digging through an Angolan dissident's MacBook last week, security researcher Jacob Appelbaum uncovered a new strain of spyware. Its purpose? To capture screenshots and beam them back to servers based in France, the Netherlands, and elsewhere.
"They can intercept text messages, and even worse, they can triangulate your position very accurately," said Nasser Weddady, director of civil rights outreach for the American Islamic Congress. "They can remotely turn your smartphone into a microphone."
This phenomenon isn't new, as protesters taking part in the Arab Spring protests discovered the hard way, but the frequency and cleverness of the attacks are on the rise. In March of 2011, one activist raided the headquarters of Egypt's state security agency and found online call files describing his own love life and trips to the beach. In 2012, an Internet-freedom report from the advocacy group Freedom House found that in 12 of 37 countries, state cyber attacks against regime critics were "intensifying."
A spyware tool called FinSpy, made by the British company Gamma Group, can clandestinely turn on Web cams and read documents as they're being typed. It has been linked to servers in more than two dozen countries, including Bahrain, where an active uprising continues to simmer. (At times, the software has even masqueraded as the browser Firefox, which prompted an angry rebuke from the Mozilla Foundation.)
A number of Western companies manufacture the technology these governments use for online monitoring, but most of the manufacturers claim to have no control over how foreign agents use their software. Reporters Without Borders went so far as to write to Skype in January and ask for better transparency about the security of Skype calls.
But as activists have become increasingly aware of such Internet strikes, they've also become savvier about the information trails they leave in the digital world.