A Netherlands-based spambot has recently been discovered that is being used to send massive volumes of spam email containing ransomware and malware. What sets this spambot aside from the many others in use is the scale of the spamming operations. Paris-based cybersecurity firm Benkow says the spambot contains an astonishing 711,000,000 email addresses.
To put that absurdly high figure into perspective, it corresponds to the entire population of Europe or two email addresses for every resident in the United States and Canada.
The spambot – called Onliner – is being used as part of a massive malware distribution network that has been distributing Ursnif banking malware. Not only are these email addresses being used for spamming and malware distribution, the passwords associated with many of those accounts are also publicly available on the same server. Malicious actors could access the data and use the information to gain access to the compromised accounts to search for sensitive information.
All of the email addresses in the list have now been uploaded to HaveIBeenPwned. Troy Hunt of HaveIBeenPwned recently explained in a blog post that this is the single largest set of email addresses that has ever been uploaded to the database. Hunt said it took 110 separate data breaches and more than two and a half years for the site to amass a database of that size.
Hunt explained that an analysis of some of the email addresses in one of the text files were all present in the data from the LinkedIn breach, another set related to the Badoo breach and another batch were all in the exploit.in list, suggesting this massive collection of email addresses has been amalgamated from past data breaches. That shows data is being extensively bought and sold on forums and darknet marketplaces. However, not all of the email addresses were already in the database, suggesting they came either from previously undisclosed breaches and scrapes of Internet sites.
Some of the lists obtained contained email addresses, corresponding passwords, SMTP servers and ports, which allow spammers to abuse those accounts and servers in their spamming campaigns. Hunt says the list includes approximately 80 million email servers that are being used in spamming campaigns.
The problem is these are legitimate accounts and servers, which the spammers can abuse to send massive amounts of spam and even defeat some spam filters, ensuring malicious messages get delivered. Hunt says authorities in the Netherlands are currently attempting to shut down Onliner.
As a precaution, everyone is recommended to visit HaveIBeenPwned to check if their email addresses/passwords have been added to the database. If they are present, it is important to update the passwords for those email accounts and never to use those passwords again.