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The dots do matter: how to scam a Gmail user

jameshfisher.com

151–160 of 518 posts

Re: The dots do matter: how to scam a Gmail user

#152

It is weird that Netflix is allowing James to update Eve's payment information without logging into Eve's account. I think that is the actual security vulnerability. On the other hand, e-mail verification should be done eventually to protect Eve from James to recovering her account in case Eve had a typo unintentionally.

Pretty sure he reset the account password using the email he has. That allowed him to access the account and view the payment information. This is why validating email addresses is critical before accepting payment information to a subscription service.

Re: The dots do matter: how to scam a Gmail user

#153
Something very similar happened to me because of the whole dot issue and Netflix not verifying their customer's email addresses (double opt-in). Someone created a Netflix account using a dot-variant of my Gmail and at some point, I received a similar email asking me to update my payment info. Right from the email, I saw it wasn't my account and thought someone else used my email by mistake (this happens a lot to me because I have a common name and a short email address).

What I usually do is request a password reset and delete the account or just remove my email address from the account. But in the Netflix case, the "update payment" button on the email log you to the account without asking for the password or anything. For the most part, people sign up to junk services/games or is just creating a throwaway account. But this was looking like a legit mistake. This person was actually using the Netflix account and had the payment info there and everything. I tried to just change the email address to something else but it required to confirm the password to change the email. I could just request a new password and change the email, but I was trying to be careful here because I didn't want to screw this person. I started to investigate a little bit more. Maybe this person had the account connected to Facebook, so it would be okay to change the password and remove my email and the account owner would still be able to log in. But it wasn't the case. I checked the watch history, just Peppa Pig and movies for kids. The name in the account was a female name. Probably a mom that created a Netflix account for her child. At this point, I was feeling super guilt to remove my email address and lock this person out of the account. All I could think of was a monday morning, the password not working, the kid crying out loud, the mom trying to figure it out. Anyway, I was just trying to not cause someone trouble.

So I thought about trying to find this person on Facebook or something. She had a not very common name so it shouldn't be hard. The payment method on Netflix was direct debit, so I had her bank account number. From the bank account number, I got the number of the bank's agency, and a quick google I discovered in which city her bank's agency was located, so it made the Facebook search very precise. There I was looking at her Facebook page. The profile picture it was a happy family of three: mom, dad, and the little child. Browsing a little bit her public feed I learned that her kid had my name (Vitor) and that explained why the account name had her name and the email address was a different name (her kid). So, either she created an email address for a 1-2 years old and mistyped it, or she just typed whatever email and created the account. The second option seemed more plausible. In any case, she seemed pretty much clueless and I thought about how to approach this and explain to her what was going on. So, I started to write a message... but it sort of started to sound weird/creepy, like how I got her contacts, and I was worried that she was going to think I was trying to scam her or something, so I gave up and said whatever. I still receive her (I mean, her kid's) movies recommendations.

Re: The dots do matter: how to scam a Gmail user

#154
post #113

Earlier quoted context omitted.

Nope. RFC 5321: "the local-part MUST be interpreted and assigned semantics only by the host specified in the domain of the address". That means it's actually technically against the RFC to do any normalization of the local-part (like ignoring dots or case).

Well, google.com assigned semantics to the local-part, which they are allowed, even supposed, to do.

My point is that the RFC doesn't say they "don't matter", it says they don't have to matter. For Netflix to assume they don't matter would be in violation of the RFC (it would be assigning semantics to the local-part).

Re: The dots do matter: how to scam a Gmail user

#155
The two security issues are user phishing and Netflix not performing canonicalization of email addresses. he signup process itself is not a security issue.

The issue from the perspective of the user should be that the author clicked on a link in an html email, when he should have instead gone to Netflix.com. He clicked first and only then checked. Gmail even warned him of the phishing possibility, and he still clicked on the link! He is the vulnerability that was almost exploited.

It is true that there are other issues with user interactions, such as Netflix allowing signups without email verification, however those were purposefully designed that way by Netflix. They are features not bugs.

Re: The dots do matter: how to scam a Gmail user

#156
post #113
post #94

Earlier quoted context omitted.

Dot's don't matter if the relevant RFC says they don't matter and I think this is the case. Google follows the standard, Netflix does not.

Nope. RFC 5321: "the local-part MUST be interpreted and assigned semantics only by the host specified in the domain of the address". That means it's actually technically against the RFC to do any normalization of the local-part (like ignoring dots or case).

Doesn't that support what Google is doing? Google is the host specified in the domain, and they are interpreting the local-part to refer to the same mailbox if they only differ by dots.

The RFC also notes that the local-part MAY be case-sensitive (i.e. it's up to the host).

Edit: the host SHOULD ignore case: "a host that expects to receive mail SHOULD avoid defining mailboxes where [...] Local-part is case-sensitive".

Re: The dots do matter: how to scam a Gmail user

#157
post #69

Totally disagree with the conclusion. This is Netflix's issue for not validating the email account. Not sure if Uber has changed this since then, but back in the day I used to get the full ride details and receipts from someone else who mistyped their email. If you are sending private transactional emails you need to verify accounts first.

If you have a bug in a system, do you fix it at the source, or do you fix it at all the leaves? Netflix might be wrong here, but fixing it at Netflix doesn't make the problem go away. Fix the problem once (GMail) and never ever have to deal with it again.

There is no bug in Gmail. This bug has nothing to do with Gmail, it is with Netflix not clearly communicating when verifying the address a user claims to own.

Re: The dots do matter: how to scam a Gmail user

#158

100% disagree. My standard gmail address is with dots but when I have to tell my (rather long because it is my full three part name) I either omit the dots or tell them they don't matter. Totally an important and useful feature. Netflix is at fault for letting someone else use your email without asking you for permission.

Why should netflix be required to adhere to the different ways that every email provider doesn't adhere to the spec?

Re: The dots do matter: how to scam a Gmail user

#159

> but I also have access to the account because I own james.hfisher@gmail.com, and so I can follow the password reset process for this account. I did so. I wonder if others feel that it is ethical or unethical to log into other people's accounts in this situation. I get lots of emails resulting from people typo'ing my email address instead of theirs—and the unsubscribe links are often hidden behind a login page. But…

When this happens to me, I reset the password and abandon the account. I assume whoever created the account made a mistake, but I have no way to contact them. When they have to sign in again, they’ll have to create a new account, but they’ll hopefully use their own email address.

It’s never happened to me with a paid account, but if it did, I’d cancel it.

Re: The dots do matter: how to scam a Gmail user

#160

Totally disagree with the conclusion. This is Netflix's issue for not validating the email account. Not sure if Uber has changed this since then, but back in the day I used to get the full ride details and receipts from someone else who mistyped their email. If you are sending private transactional emails you need to verify accounts first.

>This is Netflix's issue for not validating the email account. Eeeh, I just re-read RFC 2822. It explicitly states that the local-part of an address may contain any number of dots as long as they are separated by (if I'm reading this correctly) at least one character, and do not start with a dot. There's nothing in there that states you should treat dotted and undotted variants of an address as the same address. So,…

There is no bug in Gmail. The bug is that the vendor is sending unclear email contents.
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