A Sneaky Phish Just Grabbed My Mailchimp Mailing List

I went to the link which is on mailchimp-sso.com and entered my credentials which - crucially - did not auto-complete from 1Password. I then entered the OTP and the page hung. Moments later, the penny dropped, and I logged onto the official website, which Mailchimp confirmed via a notification email which showed my London IP address:

I immediately changed my password, but not before I got an alert my mailing list being exported from an IP address in New York:

And, moments after that, the login alert from the same IP:

This was obviously highly automated and designed to immediately export the list before the victim could take preventative measures.

There are approximately 16k records in that export containing info Mailchimp automatically collects and they appear as follows:

I'm enormously frustrated with myself for having fallen for this, and I apologise to anyone on that list. Obviously, watch out for spam or further phishes and check back here or via the social channels in the nav bar above for more. Ironically, I'm in London visiting government partners, and I spent a couple of hours with the National Cyber Security Centre yesterday talking how we can better promote passkeys, in part due to their phishing-resistant nature. 🤦‍♂️

More soon, I've hit the publish button on this 34 mins after the time stamp in that first email above.

More Stuff From After Initial Publish

Every Monday morning when I'm at , I head into a radio studio and do a segment on scams. It's consumer-facing so we're talking to the "normies" and whenever someone calls in and talks being caught in the scam, the sentiment is the same: "I feel so stupid". That, friends, is me right now. Beyond acknowledging my own foolishness, let me proceed with some more thoughts:

Firstly, I've received a gazillion similar phishes before that I've identified early, so what was different this one? Tiredness, was a major factor. I wasn't alert enough, and I didn't properly think through what I was doing. The attacker had no way of knowing that (I don't have any reason to suspect this was targeted specifically at me), but we all have moments of weakness and if the phish times just perfectly with that, well, here we are.

Secondly, reading it again now, that's a very well-crafted phish. It socially engineered me into believing I wouldn't be able to send out my so it triggered "fear", but it wasn't all bells and whistles something terrible happening if I didn't take immediate action. It created just the right amount of urgency without being over the top.

Thirdly, the thing that should have saved my bacon was the credentials not auto-filling from 1Password, so why didn't I stop there? Because that's not unusual. There are so many services where you've registered on one domain (and that address is stored in 1Password), then you legitimately log on to a different domain. For example, here's my Qantas entry:

I'll park this here and do a deeper technical dive later today that addresses some of the issues I've raised above.

I'll keep writing this bit by bit (you may see it appear partly finished while reading, so give the page a refresh later on), starting with the API key that was created:

This has now been deleted so along with rolling the password, there should no longer be any persistent access to the account.

Unfortunately, Mailchimp doesn't offer phishing-resistant 2FA:

Another interesting angle to this is the address the phish was sent to:

The rest of that address is probably pretty predictable (and I do publish my full "normal" address on the page of this blog , so it's not like I conceal it from the public), but I find it interesting that the phish came to an address only used for Mailchimp . Which leaves two possibilities:

Someone got the address from somewhere else, and I've only ever used it in one place...

Applying some Occam's razor , it's the latter. I find the former highly unlikely, and I'd be very interested to hear from anyone else who uses Mailchimp and received one of these phishes.

Still on email addresses, I originally read the phish on my iThing and Outlook rendered it as you see in the image above. At this point, I was already on the hook as I intended to login and restore my account, so the way the address then rendered on the PC didn't really stand out to me when I switched devices:

That's so damn obvious 🤦‍♂️ The observation here is that by not rendering the sender's address, Outlook on iOS hid the phish. But having said that, by no means can you rely on the address as a solid indicator of authenticity but in this case, it would have helped.

I just went to go and check on the phishing site with the expectation of submitting it to Google Safe Browsing, but it looks like that will no longer be necessary:

2 hours and 15 minutes after it snared my creds, Cloudflare has killed the site. I did see a Cloudflare anti-automation widget on the phishing page when it first loaded and later wondered if that was fake or they were genuinely fronting the page, but I guess that question is now answered. I know there'll be calls of "why didn't Cloudflare block this when it was first set up", but I maintain (as I have before in their defence), that it's enormously hard to do that based on domain or page structure alone without creating a heap of false positives.

Loading the List into Have I Been Pwned

Looking for silver linings in the incident, I’m sure I’ll refer this blog post to organisations I disclose future breaches to. I’ll point out in advance that even though the data is “just” email addresses and the risk to individuals doesn’t present a likelihood of serious harm or risk their rights and freedoms (read that blog post for more), it’s simply the right thing to do. In short, for those who read this in future, do not just as I say, but as I do.

I emailed a couple of contacts at Mailchimp earlier today and put two questions to them:

Are passkeys on your roadmap

The irony of the timing with this happening just as I’ve been having passkey discussions with the NCSC is something I’m going to treat as an opportunity. Right before this incident, I’d already decided to write a blog post for the normies passkey, and now I have the perfect example of their value. I’d also discussed with the NCSC creating a passkey equivalent of my whynohttps.com project which highlighted the largest services not implementing HTTPS by default. As such, I’ve just registered whynopasskeys.com (and its singular equivalent) and will start thinking more how to build that out so we can collectively put some pressure on the services that don’t support unphishable second factors. I actually attempted to register that domain whilst out walking today, only to be met with the following courtesy of DNSimple :

Using a U2F key on really important stuff (like my domain registrar) highlights the value of this form of auth. Today’s phish could not have happened against this account, nor the other critical ones using a phishing resistant second factor and we need to collectively push orgs in this direction.

Update 1: I'll keep adding more thoughts here via updates, especially if there's good feedback or questions from the community. One thing I'd intended to add earlier is that the more I ponder this, the more likely I think it is that my unique Mailchimp address was obtained from somewhere as opposed to guessed in any targeted fashion. A possible explanation is the security incident they had in 2022 , which largely targeted crypto-related lists, but I imagine would likely have provided access to the email addresses of many more customers too. I'll put that to them when I get a response to my earlier email.

Pondering this even further, I wonder if Mailchimp has any anti-automation controls on login? The credentials I entered into the phishing site were obviously automatically replayed to the legitimate site, which suggests something there is lacking.

I also realised another factor that pre-conditioned me to enter credentials into what I thought was Mailchimp is their very short-lived authentication sessions. Every time I go back to the site, I need to re-authenticate and whilst the blame still clearly lies with me, I'm used to logging back in on every visit. Keeping a trusted device auth'd for a longer period would likely have raised a flag on my return to the site if I wasn't still logged in.

Update 3: Mailchimp has now restored access to my account and the subscription service is working again. Here's what they've said:

We have reviewed the activity and have come to the same conclusion that the unauthorized export and API key from 198.44.136.84 was the scope of the access. Given we know how the access took place, the API key has been deleted, and the password has been reset, we have restored your access to the account.

They've also acknowledged several outstanding questions I have (such as whether passkeys are on the roadmap) and have passed them along to the relevant party. I'll update this post once I have answers.

Because we don’t consider that a suppression list is used for direct marketing purposes, there is no automatic right for people to have their information on such a list deleted.

My suggestion would be to follow our approach for Have I Been Pwned where we give people three choices and allow them to choose how they'd like their data to be handled:

At present, Mailchimp is effectively implementing the first option we provide and the folks that are upset were expecting the last option. Hopefully they'll consider a more self-empowering approach to how people's data is handled, I'll update this blog post once I have their response.

Update 4: Someone has pointed out that the sending email address in the phish actually belongs to a Belgian cleaning company called Group-f . It's not unusual for addresses like this to be used to send malicious mail as they usually don't have a negative reputation and more easily pass through spam filters. It also indicates a possible compromise on their end, so I've now reached to them to report the incident.

Update 5: I've been contacted by someone that runs a well-known website that received the same phishing email as me. They made the following observation regarding the address that received the phish:

This aligns with my earlier observation that a customer list may have been obtained from Mailchimp and used to send the phishing emails. They went on to say they were seeing multiple subsequent phishes targeting their Mailchimp account.

Btw, we got some more (Mailchimp) phishing emails today — same style, this time 4 times writing a new login detected, and once that an abuse report was received and we needed to take immediate action.

That a customer list may have been compromised was one of the questions I put to Mailchimp and am still awaiting an answer on. That was 36 hours ago now, so I've just given them a little nudge.

Update 7: Validin has written a fantastic piece Pulling the Threads of the Phish of Troy Hunt that takes a deep dive into the relationship between the domain the phish was hosted on and various other campaigns they've observed.

Given these similarities, we believe the phishing attempt of Troy Hunt is very likely Scattered Spider.

Scattered Spider certainly has form, and this was a very well-orchestrated phish. Four days on as I write this, it's hard not to be a bit impressed how slick the whole thing was.