Businesses using Office 365, Google G-Suite or other hosted environments (but especially Microsoft and Google) are vulnerable to phishing attacks that steal user credentials. Here is a recent example, which sailed through Microsoft’s spam and malware filters despite its attempts to use AI and other techniques to catch them.

If a user clicks the link and signs in, the bad guys have their credentials. What are the consequences?

– at best, a bunch of spam sent out from the user’s account, causing embarrassment and a quick password reset.

– at worst, something much more serious. Once an unauthorised party has user credentials, there are all sorts of social engineering possibilities to escalate the attack, obtain other credentials, or see what interesting data can be found in collaborative document stores and shared applications.

– another risk is to discover information about an organisation’s customers and contact them to advise of new bank details which of course direct payments to the attacker’s account.

The truth is there are many risks and it is worth every effort to prevent this happening in the first place.

However, it is hard to educate every user to the extent that you can be confident they will never click a link in an email such as the one above, or reveal their password in some other way – such as using the same one as one that has been leaked – check here to find out, for example.

Multi-factor authentication (MFA), which is now easy to set up on both Office 365 or G-Suite, helps matters by requiring users to enter a one-time code from their mobile, either via an authenticator app or a text message, before they can log in. It does not cost any extra and now is the time to set it up, if you have not already.

It seems to me that in some ways the prevalence of a few big providers in hosted email and applications has made matters easier for the hackers. They know that a phishing attack simulating, say, Office 365 support will find many potential victims.

The more positive view is that even small businesses can now easily use Enterprise-grade security, if they choose to take advantage.

I do not think MFA is perfect. It usually depends on a mobile phone, and given that possession of a user’s phone also often enables you to reset the password, there is a risk that the mobile becomes the weak link. It is well known that social engineering against mobile providers can persuade them to cancel a SIM and issue a new one to an impostor.

That said, hijacking a phone is a lot more effort than sending out a million phishing emails, and on balance enabling MFA is well worth it.