How the Great Conficker Panic Hacked into Human Credulity

By Bruce Schneier
The Guardian
April 23, 2009

This essay also appeared in the Gulf Times.

Conficker's April Fool's joke -- the huge, menacing build-up and then nothing -- is a good case study on how we think about risks, one whose lessons are applicable far outside computer security. Generally, our brains aren't very good at probability and risk analysis. We tend to use cognitive shortcuts instead of thoughtful analysis. This worked fine for the simple risks we encountered for most of our species's existence, but it's less effective against the complex risks society forces us to face today.

We tend to judge the probability of something happening on how easily we can bring examples to mind. It's why people tend to buy earthquake insurance after an earthquake, when the risk is lowest. It's why those of us who have been the victims of a crime tend to fear crime more than those who haven't. And it's why we fear a repeat of 9/11 more than other types of terrorism.

We fear being murdered, kidnapped, raped and assaulted by strangers, when friends and relatives are far more likely to do those things to us. We worry about plane crashes instead of car crashes, which are far more common. We tend to exaggerate spectacular, strange, and rare events, and downplay more ordinary, familiar, and common ones.

We also respond more to stories than to data. If I show you statistics on crime in New York, you'll probably shrug and continue your vacation planning. But if a close friend gets mugged there, you're more likely to cancel your trip.

And specific stories are more convincing than general ones. That is why we buy more insurance against plane accidents than against travel accidents, or accidents in general. Or why, when surveyed, we are willing to pay more for air travel insurance covering "terrorist acts" than "all possible causes". That is why, in experiments, people judge specific scenarios more likely than more general ones, even if the general ones include the specific.

Conficker's 1 April deadline was precisely the sort of event humans tend to overreact to. It's a specific threat, which convinces us that it's credible. It's a specific date, which focuses our fear. Our natural tendency to exaggerate makes it more spectacular, which further increases our fear. Its repetition by the media makes it even easier to bring to mind. As the story becomes more vivid, it becomes more convincing.

The New York Times called it an "unthinkable disaster", the television news show 60 Minutes said it could "disrupt the entire internet" and we at the Guardian warned that it might be a "deadly threat". Naysayers were few (bit.ly/schneier37), and drowned out.

The first of April passed without incident, but Conficker is no less dangerous today (bit.ly/schneier41, bit.ly/schneier42). About 2.2m computers worldwide, are still infected with Conficker.A and B, and about 1.3m more are infected with the nastier Conficker.C. It's true that on 1 April Conficker.C tried a new trick to update itself, but its authors could have updated the worm using another mechanism any day. In fact, they updated it on 8 April, and can do so again.

And Conficker is just one of many, many dangerous worms being run by criminal organisations. It came with a date and got a lot of press -- that 1 April date was more hype than reality -- but it's not particularly special. In short, there are many criminal organisations on the internet using worms and other forms of malware to infect computers. They then use those computers to send spam, commit fraud, and infect more computers. The risks are real and serious. Luckily, keeping your anti-virus software up-to-date and not clicking on strange attachments can keep you pretty secure. Conficker speads through a Windows vulnerability that was patched in October. You do have automatic update turned on, right?

But people being people, it takes a specific story for us to protect ourselves.

earlier essay: An Enterprising Criminal Has Spotted a Gap in the Market
later essay: Do You Know Where Your Data Are?
categories: Business of Security
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Photo of Bruce Schneier by Per Ervland.

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