LastPass, a password security firm, said on Thursday that it has found email addresses, encrypted passwords and password hints stored in clear text from Adobe user accounts on an underground website frequented by cyber criminals.
Adobe said last week that attackers had stolen data on more than 38 million customer accounts, on top of the theft of information on nearly 3 million accounts that it disclosed nearly a month earlier.
The maker of Photoshop and Acrobat software confirmed that LastPass had found records stolen from its data center, but downplayed the significance of the security firm's findings.
While the new findings from LastPass indicate that the Adobe breach is far bigger than previously known, company spokeswoman Heather Edell said it was not accurate to say 152 million customer accounts had been compromised because the database attacked was a backup system about to be decommissioned.
She said the records include some 25 million records containing invalid email addresses, 18 million with invalid passwords. She added that "a large percentage" of the accounts were fictitious, having been set up for one-time use so that their creators could get free software or other perks.
She also said that the company is continuing to work with law enforcement and outside investigators to determine the cost and scope of the breach, which resulted in the theft of customer data as well as source code to several software titles.
The company has notified some 38 million active Adobe ID users and is now contacting holders of inactive accounts, she said.
Paul Stephens, director of policy and advocacy for the non-profit Privacy Rights Clearinghouse, said information in an inactive database is often useful to criminals.
He said they might use it to engage in "phishing" scams or attempt to figure out passwords using the hints provided for some of the accounts in the database. In some cases, people whose data was exposed might not be aware of it because they have not accessed the out-of-date accounts, he said.
"Potentially it's the website you've forgotten about that poses the greater risk," he said. "What if somebody set up an account with Adobe ten years ago and forgot about it and they use the same password there that they use on other sites?"
FORGOT THE SALT?
LastPass Chief Executive Joe Siegrist said that Adobe failed to use best practices for securing the stolen passwords.
The ones in the database were not protected with a technique known as "salting," which means adding a secret code to every password after it is scrambled and before it is stored in the database. That way multiple encrypted versions of the same password never look the same.
Because the passwords were not salted, Siegrist said he was able to identify the most frequently used password in the group, which was used 1.9 million times. The database has 108 million email addresses with passwords shared in multiple accounts.
"I'd say 108 million people fall into the range of likely very easily guessable passwords," he said.
The number of records stolen appears to be the largest taken in any publicly disclosed cyber attack to date.
The largest cyber breach previously reported was a 2009 attack on Heartland Payment Systems in which more than 130 million credit card numbers were stolen, according to Privacy Rights Clearinghouse data. Hackers accessed more than 100 million records from the Sony PlayStation Network in 2011 in another notorious attack.
Mike Spanbauer, managing director of research at the security firm NSS Labs, noted that the impact of the Adobe breach might not be as significant as ones where large numbers of financial records were stolen.
Still, he said that the attack was a strong reminder that consumers and businesses need to be vigilant about making sure they do not reuse passwords.