The former security chief at Twitter told Congress that the social media platform is plagued by weak cyber defenses that make it vulnerable to exploitation by “teenagers, thieves and spies” and put the privacy of its users at risk. Peiter “Mudge” Zatko, a respected cybersecurity expert, appeared before the Senate Judiciary Committee to lay out his allegations Tuesday.

“I am here today because Twitter leadership is misleading the public, lawmakers, regulators and even its own board of directors," Zatko said as he began his sworn testimony.

He told senators he was “risking my career and my reputation” to warn of poor security practices in which too many Twitter employees had unsupervised access to sensitive information, and a corporate culture of only reporting good news up the chain.

Zatko said “Twitter leadership ignored its engineers,” in part because “their executive incentives led them to prioritize profit over security.”

His message echoed one brought to Congress against another social media giant last year, but unlike that Facebook whistleblower, Frances Haugen, Zatko hasn't brought troves of internal documents to back up his claims.

Zatko was the head of security for the influential platform until he was fired early this year. He filed a whistleblower complaint in July with Congress, the Justice Department, the Federal Trade Commission and the Securities and Exchange Commission. Among his most serious accusations is that Twitter violated the terms of a 2011 FTC settlement by falsely claiming that it had put stronger measures in place to protect the security and privacy of its users.

Sen. Dick Durbin, an Illinois Democrat who heads the Judiciary Committee, said Zatko has detailed flaws “that may pose a direct threat to Twitter’s hundreds of millions of users as well as to American democracy.”

“Twitter is an immensely powerful platform and can’t afford gaping vulnerabilities,” he said.

Unknown to Twitter users, there’s far more personal information disclosed than they -or sometimes even Twitter itself - realize, Zatko testified. He said “basic systemic failures” that were brought forward by company engineers were not addressed.

The FTC has been “a little over its head”, and far behind European counterparts, in policing the sort of privacy violations that have occurred at Twitter, Zatko said.

Many of Zatko’s claims are uncorroborated and appear to have little documentary support. Twitter has called Zatko’s description of events “a false narrative ... riddled with inconsistencies and inaccuracies” and lacking important context.

Among the assertions from Zatko that drew attention from lawmakers Tuesday was that Twitter knowingly allowed the government of India to place its agents on the company payroll, where they had access to highly sensitive data on users. Twitter’s lack of ability to log how employees accessed user accounts made it hard for the company to detect when employees were abusing their access, Zatko said.

The senators appeared less interested in Zatko's claims about how Twitter counted “spam bots" on the platform and presented that information to advertisers and regulators.

An allegation that Twitter underreports its spam count is at the core of billionaire tycoon Elon Musk’s attempt to back out of his $44 billion deal to buy Twitter. Musk and Twitter are locked in a bitter legal battle, with Twitter having sued Musk to force him to complete the deal. The Delaware judge overseeing the case ruled last week that Musk can include new evidence related to Zatko's allegations in the high-stakes trial, which is set to start Oct. 17.

Sen. Charles Grassley, the committee's ranking Republican, said Tuesday that Twitter CEO Parag Agrawal declined to testify at the hearing, citing the ongoing legal proceedings with Musk. But the hearing is “more important that Twitter’s civil litigation in Delaware," Grassley said. Twitter declined to comment on Grassley's remarks.

In his complaint, Zatko accused Agrawal as well as other senior executives and board members of numerous violations, including making “false and misleading statements to users and the FTC about the Twitter platform’s security, privacy and integrity.”

Zatko, 51, first gained prominence in the 1990s as a pioneer in the ethical hacking movement and later worked in senior positions at an elite Defense Department research unit and at Google. He joined Twitter in late 2020 at the urging of then-CEO Jack Dorsey.