BERLIN — After hackers, later determined to be working for Russia, broke into Parliament’s main computer network three years ago, the government vowed to fortify its cybersecurity. The authorities schooled lawmakers about changing passwords, using two-step identification and other measures to protect online data.

But on Friday, nearly 1,000 lawmakers and other prominent Germans, including rappers, journalists and internet personalities, awoke to find links to their street and email addresses, private chats from social media, bank account details and pictures of their children published on Twitter, in another major breach aimed at the country’s political establishment.

All those attacked had a history of criticizing the far right, whose politicians appeared to be spared, raising suspicion that the hacker or hackers were sympathetic to their agenda, though the authorities said they had no indication yet who was behind the attack.

The breach spread a fresh round of alarm in Germany, a country where citizens especially covet their privacy, and once again raised the disconcerting question of whether even the most vigilant and sophisticated individuals and governments can safeguard their computers and the valuable personal, financial and other sensitive information that resides there.