In an article for The Atlantic, Alexis Madrigal, formerly of Wired magazine, takes a detailed look at the recent battle between the Tunisian authorities and Facebook – and how Facebook responded to it. He writes:

After more than ten days of intensive investigation and study, Facebook's security team realized something very, very bad was going on. The country's Internet service providers were running a malicious piece of code that was recording users' login information when they went to sites like Facebook.

By January 5, it was clear that an entire country's worth of passwords were in the process of being stolen right in the midst of the greatest political upheaval in two decades. Sullivan and his team decided they needed a country-level solution -- and fast.

Though Sullivan [Joe Sullivan, Facebook's chief security officer] said Facebook has encountered a wide variety of security problems and been involved in various political situations, they'd never seen anything like what was happening in Tunisia.

The article continue that Facebook treated this as a technical/security problem rather than a political problem.

The software [used by the Tunisian regime] was basically a country-level keystroke logger, with the passwords presumably being fed from the ISPs to the Ben Ali regime. As a user, you just logged into some part of the cloud, Facebook or your email, say, and it snatched up that information. If you stayed persistently logged in, you were safe. It was those who logged out and came back that were open to the attack.

Sullivan's team rapidly coded a two-step response to the problem. First, all Tunisian requests for Facebook were routed to an https server. The Https protocol encrypts the information you send across it, so it's not susceptible to the keylogging strategy employed by the Tunisian ISPs.

The second technical solution they implemented was a "roadblock" for anyone who had logged out and then back in during the time when the malicious code was running. Like Facebook's version of a "mother's maiden name" question to get access to your old password, it asks you to identify your friends in photos to complete an account login.

They rolled out the new solutions to 100% of Tunisia by Monday morning, five days after they'd realized what was happening. It wasn't a totally perfect solution. Most specifically, ISPs can force a downgrade of https to http, but Sullivan said that Facebook had not seen that happen.

Posted by Brian Whitaker, 25 Jan 2011.