Collection #1 data breach sees 773 million email IDs, 21 million passwords visible in massive data dump

One of the biggest data leaks in recent years has surfaced with nearly 773 million unique email addresses and more than 21.2 million unique, plain-text passwords were openly visible in a recent massive data dump.

Collection #1 is arguably the largest data leak since Yahoo’s colossal debacle of 2013 that affected nearly three billion accounts. However, luckily, there’s no sensitive information such as credit card details, in the leaked files.

The data breach was revealed by renowned security researcher Troy Hunt who reported the massive leak consisting a constellation of 12,000 files with a total size of 87GB, and nearly 2.7 billion records, hosted on MEGA after multiple people reached out to him last week.

He added that the files have been removed from the hosting platform, but they remain on a popular hacking forum that was not named. Hunt said the forum post described the source of the data as “a collection of 2000+ dehashed databases and Combos (combinations of email addresses and passwords) stored by topic.

Chris Boyd, Lead Malware Intelligence Analyst at Malwarebytes, has commented on the data dump:

“There’s a huge amount of data, and a date range potentially going back a decade. With this in mind, the key thing is to ensure passwords haven’t been reused across multiple accounts. This is another good argument for making use of password managers, and especially those with built-in functionality to check current passwords against lists of data breaches. If you recognise any of your passwords in the haul, you should stop using it immediately and perform a little behind the scenes maintenance as soon as possible.

In addition, Oz Alashe, CEO of cybersecurity training and awareness platform, CybSafe said:

“This dump of emails and passwords will serve as a central database for criminals looking to undertake credential stuffing attacks. Compromised pairs of emails and passwords will be injected into commercial websites like Amazon and Ebay in order to fraudulently gain access to accounts. The vast majority of email and password combos won’t work, but a few will. That’s because many people reuse the same credentials on multiple websites. Although much of the data dump appears to originate from old data breaches, users are still at risk. Those affected need to act fast to change any reused passwords.”

Have you been affected?

To find out if your email ID was part of the Collection #1, check the Have I been Pwned. The site is a database to search email IDs that have been part of data leaks.

In case your email has been affected, it’s recommended that you change your password. The site also offers password search to verify if any of the data breaches contained a specific password that you used.


European Data Protection Summit will take place on June 3rd in Central London and will play host to 800 DPO’s, Security Professionals and senior business decision makers looking for; information, updates, clarity, advice and solutions. For more information, visit the website.

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