To prevent phishing, punch your employees in the face

Security consultant Dan Tentler compares an organisation's infosec defences to the human immune system, and explains how to vaccinate against phishing attacks

"How do you teach a person to duck a punch? You punch them in the face until they get it," said freelance information security consultant Dan Tentler, who designed Twitter's internal anti-phishing training program, at last week's Breakpoint security conference in Melbourne.

He's got a point. Traditional security training seem to expect people to translate abstract slogans such as "think before you click" into real-world behaviour change. But what, exactly, are they meant to be thinking about as they open their email?

The approach Tentler adopted at Twitter is based on the unique reality of the organisation's phishing threats and the metaphor of the human immune system.

Neutrophils in the immune system, for example, do more or less the same thing as infosec responders: they flood to the site of infection and deal with it. And just like you'd vaccinate someone against an infection by exposing them to a weakened, harmless version of that infection so they build antibodies, the way to improve your employees' ability to spot phishing attempts deployed against them is to hit them with your own phishing attacks.

The key issues in getting such an anti-phishing campaign right are cadence (how often do you hit people with an attack?); choosing the right pretexts (the fake emails you construct should reflect the actual threat landscape your organisation faces, and the actual spam you're receiving); monitoring the right performance metrics; managing the reveal (the landing pages that explain that they've been phished need to have the right tone, as does the educational material); and adjusting the process to improve performance.

"If your people keep getting hit with viagra spam, you need to hit them with viagra spam too," he said. By the time they get hit with a real phishing campaign, hopefully they've got some "muscle memory", as Tentler puts it, and won't automatically click.

At Twitter, Tentler measured the click-through rate from the email to the fake webpage that asked for their login credentials, and the subsequent phish rate as people went that extra step and were caught. "Your metrics will tell you which demographic of your employees is most vulnerable," he said.

"Designing the training pages that anyone can learn from them is key." Be lighthearted, but convey the seriousness of the issue. Tentler said that when someone successfully identified one of his phish attempts and reported, he would personally respond and congratulate them.

Tentler says that $5000 per quarter is plenty for this sort of program, and that to get executive buy-in you should just phish them first of all.

Overall, the whole exercise has to be fun for everyone, not Mandatory Company Training That You Must Complete Or You Will Be Fired.

Tentler also recommended that you set up all of the available anti-spam protocols on your mail server — DMARC, DKIM, and SPF — which make it almost impossible for an external attacker to spoof email on your own domains.

Contact Stilgherrian at or follow him on Twitter at @stilgherrian

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