SAN FRANCISCO/WASHINGTON • Three senior managers in Uber Technologies' security unit have resigned, a spokesman said, days after the company's new CEO disclosed a massive data breach and criticised past security practices.

Mr Dara Khosrowshahi, who was installed in the top Uber job in August, disclosed the data breach last month shortly after learning of it himself, saying that "none of this should have happened".

Uber's security practices are also under scrutiny in a high-stakes legal battle with self-driving car company Waymo, an Alphabet subsidiary.

Uber last week said it fired its chief security officer Joe Sullivan over his role in last year's breach, which compromised data belonging to 57 million customers and about 600,000 drivers. Friday's resignations came amid rising frustration within Uber's security team over Mr Sullivan's dismissal and the firm's handling of the public disclosure of the breach.

The three who quit were Mr Sullivan's chief of staff Pooja Ashok; engineer Prithvi Rai, the No. 2 manager in the department; and Mr Jeff Jones, who handled physical security, the Uber spokesman said.

A fourth person, Uber's head of global threat operations Mat Henley, began a three-month medical leave, said a separate source familiar with the situation. The departures include most of Mr Sullivan's direct reports.

None of the four immediately responded to requests for comment.

Mr Sullivan in August told Reuters that his security team totalled around 500 employees.

Leadership in the unit has been in turmoil since the termination last week of Mr Sullivan and a deputy, as well as Uber's admission that it paid US$100,000 (S$134,500) to hackers to delete stolen data from the October 2016 breach and keep it secret, while failing to report the incident to regulators or warn customers that their phone numbers and other data had been exposed.

In the Waymo case, testimony at a pretrial hearing last week focused on claims by former employee Richard Jacobs that Uber had a special unit within its security team that tried to obtain programming code and other trade secrets from rivals.

Uber launched an investigation in response to Mr Jacobs' claims, which were outlined in a 37-page letter sent to Uber's in-house attorney and the US Department of Justice.

Besides having a technical team dedicated to obtaining data from competitors, Uber also had a "human intelligence" team to spy on people and record their conversations without them knowing, according to the testimony.

REUTERS