Millions of Email Addresses Exposed in Latest Malware Database

Another week, another multi-million member list of pwned email addresses exposed on the Internet. This time it's the database of names used by a malware-spreading spambot based in the Netherlands and the result is both more and less than meets the eye.

A French security researcher who goes by the nom de hack of benkow found the stash as s/he was researching Ursnif, a trojan that steals banking credentials from unsuspecting users.

During the research, Benkow found servers with open-text (i.e., unencrypted) data files containing 711 million email addresses. According to news reports, Troy Hunt, who runs the website haveibeenpwned.com, reported that this was the largest single stash of stolen email addresses ever submitted to the site.

To make matters worse, the data files also included passwords and user names. Taken all together, this represents a store of data that might easily be used to take control of email accounts and leverage them for massive phishing and malware efforts.

The "less than meets the eye" part of the news starts with analysis presented by Troy Hunt in his blog. He reports that many of the email addresses in the data files appear to be either randomly generated addresses at known domains, lists of variations on existing email addresses or common words (like "sales") appended to legitimate email domains.

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Next, Hunt's analysis of the lists shows that virtually all of the passwords in the database were part of the 2012 Linkedin account breach. If the owners of those passwords have been at all sensible, this means that the vast majority of the passwords in the list are no longer valid, save as a sort of template through which new passwords might be guessed.

Even with the "good news" contained in these two points, there is tremendous danger in both the breach and the disclosure of this massive database. In a written statement provided to Security Now, Christian Lees, CTO and CSO of InfoArmor, said, "Continuous large data disclosures of this type, with potentially unverifiable data sources and targets, increase alert fatigue for security professionals." On the other hand, he pointed out, "This is another reminder that threat actors also live the dual-edge sword of security."

Security professionals are working with authorities in the Netherlands to shut down the servers holding the database and acting as command and control for Ursnif.

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— Curtis Franklin is the editor of SecurityNow.com. Follow him on Twitter @kg4gwa.