'This is probably the worst thing that could have happened,' said Brad Bussie, director of product management at Stealthbits Technologies. Why it took so long for Yahoo to find out and inform the public wasn't clear from the company's statementВ on the breach. Security experts like Holden have noted that some people rely on Yahoo email for work purposes, putting corporate information potentially at risk.

'Yahoo was once the number one email provider.'ДЄccording to Yahoo, the breach disclosed on Thursday involved data taken from late 2014 - meaning hackers had two years to secretly capitalize on what they stole. 'The Yahoo data breach will have a much bigger impact than almost any other breach that I can speak of,' Holden said. Still, Alex Holden, CIO at security firm Hold Security,В wonders how many hackers are in possession of the company's stolen database. The company hasn't said if the two incidents are connected. In August, an anonymous hacker was foundВ selling a database with login details on 200 million Yahoo accounts. Prior to Thursday's confirmed breach, Yahoo had already been investigating another leak. 'They couldn't just come in and take the grand piano.' 'The hackers probably attacked slowly, and quietly, without anyone watching,' Kremez said. Stealing data on 500 million accounts is usually no easy task, he added. Yahoo has blamed the attack on a 'state-sponsored actor,' but it's far from clear who hacked the internet company and how the culprits pulled off the attack.Д«laming it on a state-sponsored actor, however, indicates that Yahoo may have found evidence that the hackers were targeting the company over a long period of time, said Vitali Kremez, a cybercrime analyst atВ security firm Flashpoint. Information including names, email addresses, telephone numbers, and hashed passwords may have been stolen. The massive breach at Yahoo means that a treasure trove of stolen data is in the hands of hackers - putting millions of internet users at risk.ДЄt least half a billion Yahoo accounts have beenВ affectedВ in one of the biggest data breaches in history.

Online trove hacks