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I’m the CTO of Mercury You shouldn’t get the device verification requirement if you’ve used the device before (we store a permanent cookie to check this) or fo

I’m the CTO of Mercury You shouldn’t get the device verification requirement if you’ve used the device before (we store a permanent cookie to check this) or for the same IP. Any chance your cookies are being cleared regularly? We added this after attackers created clones of http://mercury.com http://mercury.com and took out Google ads for it. When customers entered their password and TOTP on the phishing site, the phisher would use their credentials to login and create virtual cards and buy crypto/gold/etc. The phisher would also redirect the user to the real Mercury and hope they figured it was a blip. This device verification link we send authorizes the IP/device you open it on, which has almost entirely defeated the phishers. Since WebAuthn is immune to this style of phishing attack, we don’t require device verification if you use it. I highly recommend using TouchID/FaceID or your device’s flavor of WebAuthn if you can—it’s more convenient and more secure. You can add it here: https://app.mercury.com/settings/security https://app.mercury.com/settings/security That said, we are talking internally about your post and we do recognize that as IPv6 gets more traction IPs will rotate much more regularly, so we’ll think if we should loosen restrictions on being a same-IP match.

deleted 2y ago
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dpifke 2y ago
Yes, I clear cookies every time I close my browser, as a layered approach to privacy on top of uBlock Origin and NoScript. There isn't a great way to exclude certain sites from this, other than setting up a dedicated web browser in a container just for Mercury. I wasn't aware that WebAuthn didn't have this requirement. I prefer TOTP because I actually like having a second factor in addition to a credential stored on my computer's hard drive (whether a password or a private key in my password manager), but I might be willing to reduce my security posture to get rid of this annoyance. One suggestion: the link would be half as annoying if it was easily cut-and-pasteable rather than a long email-open-tracking link spanning multiple lines. This is what it looks like when I copy it out of my email: https://email.mg.mercury.com/c/eJxMzs1u4jAUBeCncXZB9vVfvPACZshoWIwYoiasdgkra2KV_JCGqPTpK-imq7xxx40vlO9IKia6ggL6zUlQHObdF6\ JI0alRHBWQvWKRuD4loLZxsJSRXZAwfNBQeQWozasdgeWsMyFZozE4RKZ4d151NOFtuq9w6IqLb-d5fGdyzaBmUIdx_NkzqBeacrqXkZaMxGSNQyQmf7_9GW7\ Hf1cJ8zW9TshAwwba3ccLuN3u_r_PR9j_GkxxxmadDu32c59jMfkYFmKKP0baIT0vzP4ynHN_-yyhZOTy9jmPPQn6gL-VLMfvvIA_XxbywRYhUbZUp0RpVCUC\ qDsbasJHeObFMZ4YrFw1cAAAD__4XPZXw I have to manually remove the backslashes and re-combine the lines before pasting into my web browser. Edit to add: looks like email.mg.mercury.com is hosted by Mailgun. Are you intentionally sharing these authentication tokens with a third party by serving them through this redirect? Do your security auditors know about this?
- jeremyjh 2y ago
  You have to send emails through third parties or people won't get them, because you are also always sending them to third parties who host the recipients email and manage their spam. It might be a good reason not to send magic links but here we are talking about a tertiary confirmation, so its useless on its own right?
  - dpifke 2y ago
    The link in the email could be a direct link to Mercury's website, rather than one that passes through a third-party HTTP redirect service. Authentication tokens (even tertiary ones) usually are supposed to have pretty strong secrecy guarantees. I've done multiple security audits for SOC, PCI, HIPAA, etc., and in every case the auditors would have balked if I told them signin tokens were being unnecessarily logged by a third-party service. (Also: I strongly disagree that the only way to get reliable delivery is via a third-party email service, especially at Mercury's scale, but that's a digression from the topic at hand.)
    - MaxGabriel 2y ago
      Oh good find, the link going through Mailgun as a redirect is a recent regression. We have a PR to fix that going live soon. That said, our security team and I agree there is no security issue here. Mailgun already can see the text of the emails we send.
      - dexterdog 2y ago
        How is there no security issue here? Email is not secure and it's even less so when you are sending it via a 3rd party. If this were a photo site or something that would not be a big deal but we're talking about a bank. SMS is not much better. Like somebody said elsewhere in the thread, you should allow people to opt out of insecure third-factor verifications since they are just an annoyance and are ultimately security theater.
        2y ago
m463 2y ago
I like the schemes that send a numeric verification code that you manually type in without an email link. can also use a text message. Maybe allow this to be configured. security = 1/convenience but also vice versa
miyuru 2y ago
> IPv6 gets more traction IPs will rotate much more regularly unfortunately, only few ISPs do IPv6 correctly by assigning a fixed prefix to customers. most of the ISPs apply the ipv4 logic when adding ipv6 planning hence this situation. hopefully this will improve in the future and more stable prefixes will be given to users.

deleted 2y ago

[deleted]

dpifke 2y ago

Yes, I clear cookies every time I close my browser, as a layered approach to privacy on top of uBlock Origin and NoScript. There isn't a great way to exclude certain sites from this, other than setting up a dedicated web browser in a container just for Mercury. I wasn't aware that WebAuthn didn't have this requirement. I prefer TOTP because I actually like having a second factor in addition to a credential stored on my computer's hard drive (whether a password or a private key in my password manager), but I might be willing to reduce my security posture to get rid of this annoyance. One suggestion: the link would be half as annoying if it was easily cut-and-pasteable rather than a long email-open-tracking link spanning multiple lines. This is what it looks like when I copy it out of my email: https://email.mg.mercury.com/c/eJxMzs1u4jAUBeCncXZB9vVfvPACZshoWIwYoiasdgkra2KV_JCGqPTpK-imq7xxx40vlO9IKia6ggL6zUlQHObdF6\ JI0alRHBWQvWKRuD4loLZxsJSRXZAwfNBQeQWozasdgeWsMyFZozE4RKZ4d151NOFtuq9w6IqLb-d5fGdyzaBmUIdx_NkzqBeacrqXkZaMxGSNQyQmf7_9GW7\ Hf1cJ8zW9TshAwwba3ccLuN3u_r_PR9j_GkxxxmadDu32c59jMfkYFmKKP0baIT0vzP4ynHN_-yyhZOTy9jmPPQn6gL-VLMfvvIA_XxbywRYhUbZUp0RpVCUC\ qDsbasJHeObFMZ4YrFw1cAAAD__4XPZXw I have to manually remove the backslashes and re-combine the lines before pasting into my web browser. Edit to add: looks like email.mg.mercury.com is hosted by Mailgun. Are you intentionally sharing these authentication tokens with a third party by serving them through this redirect? Do your security auditors know about this?

jeremyjh 2y ago
You have to send emails through third parties or people won't get them, because you are also always sending them to third parties who host the recipients email and manage their spam. It might be a good reason not to send magic links but here we are talking about a tertiary confirmation, so its useless on its own right?
- dpifke 2y ago
  The link in the email could be a direct link to Mercury's website, rather than one that passes through a third-party HTTP redirect service. Authentication tokens (even tertiary ones) usually are supposed to have pretty strong secrecy guarantees. I've done multiple security audits for SOC, PCI, HIPAA, etc., and in every case the auditors would have balked if I told them signin tokens were being unnecessarily logged by a third-party service. (Also: I strongly disagree that the only way to get reliable delivery is via a third-party email service, especially at Mercury's scale, but that's a digression from the topic at hand.)
  - MaxGabriel 2y ago
    Oh good find, the link going through Mailgun as a redirect is a recent regression. We have a PR to fix that going live soon. That said, our security team and I agree there is no security issue here. Mailgun already can see the text of the emails we send.
    - dexterdog 2y ago
      How is there no security issue here? Email is not secure and it's even less so when you are sending it via a 3rd party. If this were a photo site or something that would not be a big deal but we're talking about a bank. SMS is not much better. Like somebody said elsewhere in the thread, you should allow people to opt out of insecure third-factor verifications since they are just an annoyance and are ultimately security theater.
      - 2y ago

m463 2y ago

I like the schemes that send a numeric verification code that you manually type in without an email link. can also use a text message. Maybe allow this to be configured. security = 1/convenience but also vice versa

miyuru 2y ago

> IPv6 gets more traction IPs will rotate much more regularly unfortunately, only few ISPs do IPv6 correctly by assigning a fixed prefix to customers. most of the ISPs apply the ipv4 logic when adding ipv6 planning hence this situation. hopefully this will improve in the future and more stable prefixes will be given to users.