Web Applications Stack Exchange is a question and answer site for power users of web applications. It only takes a minute to sign up.
Sign up to join this community
Someone sent a message to 4 friends on Facebook. It wasn't me, and couldn't've been me, since I was driving at the time. Nobody else has access to my account. The only 2 devices that are logged into this account were on my possession. Under "security", I can see no unrecognized location. The message was a link my girlfriend sent to me yesterday!
What does this mean? If my girlfriend (or anyone, really) somehow accessed my account, shouldn't it show on "security"? That doesn't make sense at all.
It is quite possible that you tried using "Login using Facebook" to a 3rd party app that asks for your permission to send messages on your behalf. If you had given such permission to a malicious app this can happen. Although, the chances are slim, but is quite possible.
If that was a spammy link, and you clicked it, that must be the cause. It happens many times that an unknown link is sent by your friend, and the moment you click it and perform some actions, your account gets hacked (sort of), and then many automatic messages goes out from your account without your knowledge. And it won't show in your account activity (suspicious login activity).
If you have any sessions not properly logged out , there is a chance of others using your account. There are more ways Facebook can be hacked, one way is a person knowing your user account or the mobile number associated with it.
Change your privacy settings so that the allowed persons can only view your personal stuff and logout sessions if you have used Facebook in any other devices.
