WASHINGTON >> 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 today.

“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. “They don’t know what data they have, where it lives and where it came from and so, unsurprisingly, they can’t protect it,” Zatko said. “It doesn’t matter who has keys if there are no locks.”

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

One issue that didn’t come up in the hearing was the question of whether Twitter is accurately counting its active users, an important metric for its advertisers.

Tesla CEO Elon Musk, who is trying to get out of a $44 billion deal to buy Twitter, has argued without evidence that many of Twitter’s roughly 238 million daily users are fake or malicious accounts, i.e. “spam bots.” 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.

Separately today, Twitter’s shareholders voted on the deal, which they were expected to easily approve.

Zatko’s 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 of their personal information disclosed than they — or sometimes even Twitter itself — realize, Zatko testified. He said Twitter did not address “basic systemic failures” brought forward by company engineers.

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.

Sen. Lindsey Graham, a Republican from South Carolina, said one positive result that could come out of Zatko’s findings would be bipartisan legislation to set up a tighter system of regulation of tech platforms.

“We need to up our game in this country,” he 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 today 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.

Zatko said he spoke with “high confidence” about a foreign agent that the government of India placed at Twitter to “understand the negotiations” between India’s ruling party and Twitter about new social media restrictions and how well those negotiations were going.

He also said he was “surprised and shocked” by an exchange with Parag Agrawal about Russia — in which Twitter’s current CEO, who was chief technology officer at the time, asked if it would be possible to “punt” content moderation and surveillance to the Russian government, since Twitter doesn’t really “have the ability and tools to do things correctly.”

“And since they have elections, doesn’t that make them a democracy?” Zatko recalled Agrawal saying.

Sen. Charles Grassley, the committee’s ranking Republican, said today that 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.