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Comment by willis936

4 months ago

Is there not a security problem if your phone number is seized? I don't need excuses about the likelihood of the threat model.

13 comments

willis936

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godelski  4 months ago

If your number is seized then the new account holder has no chat history. i.e. the vault is cleared out. In that situation you will also be kicked out, clearly telling you that your account has been hijacked.

You can also lock registration of your device.

What is your security concern here?

  • AnonC  4 months ago

    > You can also lock registration of your device

    Registration lock expires in seven days or less. [1]

    [1]: https://support.signal.org/hc/en-us/articles/360007059792-Si...

    • godelski  4 months ago

      Please actually read

        > Registration Lock expires after 7 days *of inactivity*

      I don't know why you dropped "of inactivity" and changed it to "or less".

      If you use signal once a week you're fine. Maybe it should be longer but that's a different argument and there's no reason to be disingenuous about it

      4 replies →

  • beeflet  4 months ago

    Impersonation, MITM attack

    • mandevil  4 months ago

      If you have done the out-of-band safety number verification, then impersonation attempts will give you a warning that their safety number has changed. I know this because I got that error when my wife replaced her cell phone.

      I believe (though I haven't verified it myself) that even if you haven't verified the numbers using an out-of-band exchange mechanism, you will get a warning if the safety number as observed by their server changes. I believe they would need to know your Signal PIN to restore from backup, which means that even if you've set that it will give an alert, presuming basic security competence from the people you are conversing with.

      2 replies →

    • godelski  4 months ago 

        > Impersonation

      Yes, but with a canary. Would you rather not have a canary? The other person also receives a warning that the verification number has changed. It's not like the existence of a phone number is what creates the ability to hijack an account. And again, you can do registration locking so that solves that problem.

      You can also do verification of your contacts. Best done in person where you can check the keys.

        > MITM attack

      I don't think that means what you think it means. Who is in the middle? This is E2EE