A sign is posted outside of the Twitter headquarters in San Francisco. (Justin Sullivan/Getty Images)

SAN FRANCISCO (CBS SF and AP) – A day after the NFL revealed its official Twitter account had been hacked, the San Francisco social media giant was denying new reports Thursday of a massive security breach.

The website LeakedSource said it received a cache of Twitter data that contains 32 million records, including passwords. But, the website said the explanation for the breach is likely malware that infected some browsers including Chrome and Firefox.

Twitter said in an official statement that its systems haven’t been breached.

“In fact, we’ve been working to help keep accounts protected by checking our data against what’s been shared from recent other password leaks,” Twitter said in

a statement.

Over a week ago, LeakedSource reported that more than 360 million records from MySpace were obtained from a hacking incident in 2013. The website has also reported that data from 167 million LinkedIn accounts were also affected from a prior hacking incident.

ZDNet said a Russian hacker named Tessa88 has claimed to be in possession of the passwords, email addresses and user names of 379 million Twitter accounts. The hacker reportedly is attempting to sell the information on the dark web for 10 bitcoins or the equivalent of $5,810.

Meanwhile, the NFL has “engaged law enforcement” to look into how its Twitter account was hacked with a post purporting that Commissioner Roger Goodell had died.

“We have engaged law enforcement to look into the matter,” NFL spokesman Brian McCarthy said Tuesday. “We are reviewing and strengthening our cyber-security measures.”

Around midday Tuesday, a post went up on the league’s official account that read: “We regret to inform our fans that our commissioner, Roger Goodell, has passed away. He was 57,” followed by a hashtag and “RIP.”

That tweet was soon deleted, as were follow-up tweets that said: “Oi, I said Roger Goodell has died. Don’t delete that tweet,” and, as other Twitter users surmised it was a hack: “OK, OK, you amateur detectives win. Good job.”

Goodell later jokingly tweeted, “Man, you leave the office for 1 day of golf” with former Bills quarterback Jim Kelly and “your own network kills you off,” followed by a hashtag and “harsh.”

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