Several months after Yahoo warned users of a third data breach that occurred between 2015 and 2016, U.S. District Judge Lucy Koh in San Jose, California has said that breach victims now have the right to sue the company, allowing them to pursue breach of contract and unfair competition claims (via Reuters). Previously, Yahoo argued that these individuals lacked grounds to sue the company, but Koh has now rejected that claim.
This leaves "well over 1 billion users" open to sue the company, all of whom were affected by one of three total data breaches that began to gain notoriety in September 2016, when the company disclosed that "at least" 500 million Yahoo accounts were compromised in a late 2014 cyber attack. A second attack was disclosed in December 2016, regarding a user information leak that happened in August 2013, and then the third and presumably last warning about a previous attack came in February 2017.
This outlined a period of data breaches that began in 2013 and lasted until 2016, with Yahoo waiting more than three years to reveal information about any of the attacks. Breached info related to names, email addresses, telephone numbers, birth dates, hashed passwords, and both encrypted and unencrypted security questions and answers.
Because each affected user now faces the risk of identity theft, Koh ruled in a 93-page decision that plaintiffs can now amend previously dismissed complaints to gain new legal ground against Yahoo.
“All plaintiffs have alleged a risk of future identity theft, in addition to loss of value of their personal identification information,” the judge wrote. Koh said some plaintiffs also alleged they had spent money to thwart future identity theft or that fraudsters had misused their data. Others, meanwhile, could have changed passwords or canceled their accounts to stem losses had Yahoo not delayed disclosing the breaches, the judge said.
“We believe it to be a significant victory for consumers, and will address the deficiencies the court pointed out,” John Yanchunis, a lawyer for the plaintiffs who chairs an executive committee overseeing the case, said in an interview. “It’s the biggest data breach in the history of the world.”
Yahoo's disclosure of the security breaches came in the midst of its acquisition by Verizon, and ended up affecting the carrier's offer. After an initial offer of $4.83 billion, Verizon ended up purchasing Yahoo's core business assets for $4.48 billion in order to limit potential liability. The deal closed this past summer and at the same time, Verizon announced plans to lay off about 2,100 Yahoo employees.