Facebook login-via-email-link option BLURTED user secrets
Facebook has been forced to kybosh a security-lite feature that offered an auto login shortcut to its users, after a privacy flaw was unsurprisingly uncovered.
The shortcut in question had allowed Facebookers to access the site simply by clicking on a web link sent to their email addresses.
But Hacker News uncovered late last week that the shortcut links had been made “publicly available” online. It further claimed that more than one million Facebook accounts had been affected, after the links had been posted and searched for on the web.
Facebook has since yanked the feature from its site after admitting that anyone accessing the links could then view the pages associated with the shortcut as well as the email addresses of those users whose details were exposed.
An engineer at the company responded on Friday about the shortcut. Matt Jones said:
We only send these URLs to the email address of the account owner for their ease of use and never make them publicly available. Even then we put protection in place to reduce the likelihood that anyone else could click through to the account.
For a search engine to come across these links, the content of the emails would need to have been posted online (e.g. via throwaway email sites, as someone pointed out – or people whose email addresses go to email lists with online archives).
[D]ue to some of these links being disclosed, we’ve turned the feature off until we can better ensure its security for users whose email contents are publicly visible. We are also securing the accounts of anyone who recently logged in through this flow.
As noted by security vendor Sophos, Facebook had embedded a cookie-like identifier into the links in question to help its users avoid having to re-enter their login credentials.
But it’s clear that such a function will always weaken an account holder’s security.
Hopefully this isn’t a news flash, but emails are not secure nor private if you haven’t encrypted them.
This is the same reason we don’t email people our credit card information and don’t send new passwords to people via email. It’s not secure.
Facebook has suspended the practice, albeit temporarily. Let’s hope they wise up and realise this cannot be done safely and leave it disabled permanently.
Most users stay logged into Facebook and don’t clear their cookies as it is, having a password bypass by magic link is simply unnecessary.