We’ve discussed phishing, quishing, smishing, insider threats, and other methods that cyber criminals use to gain access to your accounts – but what about email bombing?
Email bombing is a malicious attack that includes cyber criminals sending a barrage of emails to a mailbox to overwhelm the server. They are a type of denial-of-service attack, aiming to cause frustration, distract the user, and cripple email servers, while also spreading malware.
When hundreds (or thousands) of spam emails overwhelm a mailbox, legitimate emails become buried amongst all the spam. The user struggles to carry on with work and misses genuine emails regarding sign-in attempts, financial transactions, or online order confirmations. Then, the cyber criminals can pretend to be the genuine IT team, enticing the user to click links, give access to their device, and more.
There are different types of email bombing attacks too. Attachment attacks involve sending large and malicious attachments that consume significant server resources when opened. List-linking attacks exploit mailing lists or group emails and reply-all attacks do the same but create an infinite thread of emails through reply-all responses. Mass mailing includes bombarding one account with a substantial number of emails using automation, and zip-bombs include a highly compressed attachment that, when opened, expands to an enormous size and wreaks havoc across the system.
Recently, one of our customer’s experienced mass mailing attacks in a couple of their users’ mailboxes. Once notified, the Techcare team blocked the accounts from receiving external emails and checked for breaches. Once it had been confirmed that the accounts were safe, the team could begin the clean-up job to restore the account to a workable condition.
But, to reduce your chances of getting email bombed, the following things should be in place:
- Strict security policies and training to recognise malicious emails and attachments.
- Email delivery software with robust anti-malware features to detect malicious attachments.
- Bulk email filters to move mass emails into a separate folder straight away.
If you think you’re experiencing an email bomb attack, then get in touch with your IT team or managed IT provider immediately. This kind of attack is time-sensitive, so you can reduce the impact by acting quickly.
