All my 2 factor authentication used to come from Google sms, but recently I've had the following numbers come up on my phone. I realise that to do this the person would need to have my phone number. I checked and this seems to be a number in canada. I did have a strange phone call from canada about a week ago but not sure if this is connected. Does anyone know if this is just my jumpiness or if this a legit attack. If it is, how can I prevent?
These appear to be valid Canadian numbers but are not Google numbers so not legit. Also not likely to actually be from the numbers listed. Far too easy to spoof caller ID's I'm afraid.
Scammers don't need your number, most operators have a range and auto-dialers can call huge numbers of phones in a short space of time.
Unfortunately there is little you can do though it may be worth reporting to your carrier, your local telecoms regulator and your local law enforcement organisation specialising in cyber crime if you have one (Action Fraud in the UK for example). Although you won't normally get much response, occasionally, when a large number of reports are received, something may be done about it.
Change your password soon & possibly use google authenticator application. You might not be in attack with Man In Middle because I have seen gmail throwing me an error of untrusted connection when i had tried to filter my web content using openDNS (google uses https). But it can be a attack of phishing which later on redirects you to your google account.