Massive data breach confirms what you already knew: you are getting spam

Posted by   Martijn Grooten on   Sep 4, 2017

The security community spends a lot of time and effort researching the infrastructure used by spammers to send billions of unwanted and often malicious emails every day – but there is something else spammers need in order to send you their emails: your email address.

Security researcher Benoît Ancel's recent discovery of various databases used by spammers confirms that they don't have a shortage of email addresses: various files containing in total more than 700 million email addresses were found in an open directory on a server used by the Onliner spambot.

This would make it one of the biggest data breaches ever known, but it is unlikely that the 700 million email addresses are the result of a single breach. Rather, it is more likely that the data was collected from various sources; for instance, the files appear to contain the full list of email addresses stolen in LinkedIn's 2012 breach.

As the data has been uploaded to Troy Hunt's Have I been pwned? service, I was able to check a number of the domains I control. I noticed the absence of recent email addresses (including several 'tagged' addresses known to have fallen into the hands of spammers), as well as the presence of some addresses that have not been used for a decade or more, and several non-existent addresses.

onliner_spambot_hibp.png


If they could, spammers would send spam only to valid and actively used addresses: invalid or retired addresses often function as spam traps, which in turn feed into IP blacklists and content filters. Hitting a spam trap is a pretty good way of getting most of the subsequent emails in a spam campaign blocked. But once you start sending millions of unwanted emails, such traps are impossible to avoid – so spammers don't bother, and focus on quantity rather than the quality of the emails they send.

This explains why scrapers that look for email addresses on websites and in mailboxes often pick up strings that look like, but aren't, email addresses, such as Message IDs, and why spammers often try common local-parts (such as info@ or john@) on domains, hoping to reach more inboxes. The fact that lists of addresses are actively sold on underground forums where spammers hang out means that is is not unlikely that some of these lists are artificially inflated by the inclusion of fake addresses.

This doesn't make the discovery of the spammer databases any less interesting though, and it is likely that a significant majority of the addresses in the list are actively in use. Usually, if your data appears in a breach some action is recommended, such as changing your password or closing your account. In this case, there is no need for that: if your email address was present in this data breach, it confirms what you no doubt already knew: you are getting spam.

However, the databases discovered by Benoît also feature a second set of data, which includes passwords. In his blog post, Benoît conjectures that these are used by spammers to try and log into SMTP servers to send spam, although the source of this data may still be other breaches: the spammers would just hope that people used the same password for their ISP's SMTP server as they had on some online service. It is a good reminder of the first rule of password security: never reuse passwords.

A VB2017 reserve paper by CERT Poland researchers Maciej Kotowicz and Jarosław Jedynak analyses a number of active spambots. All reserve papers will be presented in Madrid (if not needed as reserves, they will be presented in the 'Small Talks' stream), so don't forget to register for the conference! Last year, at VB2016, Benoît and his then colleague Mehdi Talbi presented a paper on Haka, an open-source language for monitoring, debugging and controlling malicious network traffic.

The security community's praise for Have I been pwned? is well deserved: not only is it an excellent source to help you find which of your data has been breached, Troy's ethics in dealing with what is ultimately other people's data are a great example for the security community.

twitter.png
fb.png
linkedin.png
hackernews.png
reddit.png

 

Latest posts:

VB2019 conference programme announced

VB is excited to reveal the details of an interesting and diverse programme for VB2019, the 29th Virus Bulletin International Conference, which takes place 2-4 October in London, UK.

VB2018 paper: Under the hood - the automotive challenge

Car hacking has become a hot subject in recent years, and at VB2018 in Montreal, Argus Cyber Security's Inbar Raz presented a paper that provides an introduction to the subject, looking at the complex problem, examples of car hacks, and the…

VB2018 paper and video: Android app deobfuscation using static-dynamic cooperation

Static analysis and dynamic analysis each have their shortcomings as methods for analysing potentially malicious files. Today, we publish a VB2018 paper by Check Point researchers Yoni Moses and Yaniv Mordekhay, in which they describe a method that…

VB2019 call for papers closes this weekend

The call for papers for VB2019 closes on 17 March, and while we've already received many great submissions, we still want more!

Registration open for VB2019 ─ book your ticket now!

Registration for VB2019, the 29th Virus Bulletin International Conference, is now open, with an early bird rate available until 1 July.

We have placed cookies on your device in order to improve the functionality of this site, as outlined in our cookies policy. However, you may delete and block all cookies from this site and your use of the site will be unaffected. By continuing to browse this site, you are agreeing to Virus Bulletin's use of data as outlined in our privacy policy.