Yahoo Issues Malicious Activity Warnings As Acquisition Value Drops
Yahoo has issued warnings to some users that their account may have been compromised between 2015 and 2016 through a ‘forged cookie’ attack.
The attack is in addition to previous data breaches disclosed by Yahoo. While Yahoo announced in December last year it was investigating how forged cookies had allowed third parties to access accounts without a password, this week users began to receive warnings that said “Based on the ongoing investigation, we believe a forged cookie may have been used in 2015 or 2016 to access your account.”
“An unauthorized third party accessed the company’s proprietary code to learn how to forge cookies,” Yahoo said in a December statement.
“Outside forensic experts have identified user accounts for which they believe forged cookies were taken or used. Yahoo is notifying the affected account holders, and has invalidated the forged cookies”
In September last year, Yahoo announced that 500 million accounts had been compromised in a 2014 attack, and two months later revealed 1 billion accounts had been breached in a 2013 attack.
According to Yahoo, the 500 million accounts breached in 2014 and the forged cookie attack were both linked to a “state-sponsored actor.”
A report from Bloomberg indicates that Verizon, which originally agreed to acquire Yahoo’s online operations for US$4.8 billion, is in the final stages of a deal for US$250 million less due to the data breaches.
As part of the deal, Verizon will share future legal responsibility for the data breaches with Altaba, a new company name for the remaining assets of Yahoo after the acquisition including a 15% stake in Alibaba.