Security experts say the latest discovery of a breach that happened so long ago is another black mark for the company.
“It’s not just one sophisticated adversary that gets in,” said Ben Johnson, co-founder and chief security strategist at Carbon Black, a security company.
Bob Lord, Yahoo’s chief information security officer, said in a statement that the state-sponsored actor in the 2014 attack had stolen Yahoo’s proprietary source code.
Outside forensics experts working with Yahoo believe that the state-sponsored hackers used Yahoo’s code to access user accounts without their passwords by creating forged “cookies,” short bits of text that a website can store on a user’s machine.
Johnson added that the scale of the breaches is only increasing as companies store more and more troves of information in similar databases.Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.SAN FRANCISCO — Yahoo, already reeling from its September disclosure that 500 million user accounts had been hacked in 2014, disclosed Wednesday that a different attack in 2013 compromised more than 1 billion accounts.
The two attacks are the largest known security breaches of one company’s computer network.
In July, Yahoo agreed to sell its core businesses to Verizon Communications for .8 billion.