Nov. 8th, 2010

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In a spectacular display of missing the point, a group of “security researchers” released a Firefox plugin called BlackSheep, designed to combat Firesheep by detecting if it’s in use on a network and, if so, warning the user.

To explain why this is at best pointless and at worst harmful, let’s recapitulate what Firesheep does: By listening to unencrypted traffic on a network (e.g. an unsecured wireless network), it steals authentication cookies and makes it trivial to hijack sessions on social networks like Facebook.

Let’s use an analogy. Suppose some auto makers, Fnord and eHonda and so on, were to release a bunch of remote controls that could be used to unlock their cars and start the engines. Suppose, furthermore, that these remote controls were very poorly designed: Anyone who can listen to the remote control signals can copy them and use them to steal your car. This takes a bit of technical know-how, but it’s not exactly hard, and it means that anyone with a bit of know-how and a bit of malice can hang around the parking lot, wait for you to use your remote, and then steal your car while you’re in the shop.

Now suppose a bunch of guys come along and say Hey, that’s terrible, we need to show people how dangerous this situation is, and they start giving away a device for free that allows anyone to listen to remotes and steal cars. What this device is to Fnord and eHonda remotes is exactly what Firesheep is to Facebook, Twitter, and so forth. What’s important to realise is that the device is not the problem. It does allow the average schmoe, or incompetent prankster, to steal your car (or use your Facebook account), but the very important point is that the car thieves already knew how to do this. Firesheep didn’t create a problem, but by making it trivial for anyone to exploit the problem, they generated a lot of press for the problem.

What the Firesheep guys wanted to accomplish was for Facebook and Twitter and so on to stand up and, in essence, say Whoops, we clearly need to make better remote controls for our cars. (It’s actually much easier for them than for our imaginary auto manufacturers, though.) True, Firesheep does expose users to pranksters who would not otherwise have known how to do this, but the flaw was already trivial to exploit by savvy attackers, which means that people who maliciously wanted to use your account to spam and so forth could already do so.

Now along come the BlackSheep guys and say, Hey, that’s terrible, the Firesheep guys are giving away a remote that lets people steal other people’s cars!, and create a detection device to stop this horrible abuse. But of course that doesn’t address the real point at all, because the real point has nothing to do with using Firesheep maliciously, but to illustrate how easy it was to attack a flawed system.

This is stupid for several reasons:

  1. If BlackSheep gets press, it might create an impression that the problem is solved. It isn’t, of course, firstly because Firesheep wasn’t the problem to begin with, and secondly because BlackSheep only runs in, and protects, Firefox.

  2. People running badly protected websites like Facebook could use BlackSheep as an excuse not to solve the real problem, by pretending that Firesheep was the problem and that problem has been solved.

  3. Even as a stop-gap measure, BlackSheep is a bad solution. The right solution is for Facebook and Twitter and so on to force secure connection. Meanwhile, as a stop-gap solution, the consumer can install plugins like the EFF’s HTTPS Everywhere that forces secure connections even to sites that don’t do it automatically. This is a superior solution: BlackSheep tells you when someone’s eavesdropping on you; HTTPS Everywhere prevents people from eavesdropping in the first place.

    Let me restate this, because I think it’s important: BlackSheep is meaningful only to people with sufficient awareness of the problem to install software to combat it. To such people, it’s an inferior solution. The correct solution is not to ask consumers to do anything, but for service providers (Facebook, Twitter, …) to fix the problem on their end; but if a consumer does anything, BlackSheep shouldn’t be it.

As I write this post, I hope that BlackSheep will get no serious press beyond a mention on Slashdot. It deserves to be forgotten and ignored. In case it isn’t ignored, though, there need to be mentions in the blogosphere of how misguided it seems.

Let’s all hope that Facebook, Twitter, and others get their act together; meanwhile install HTTPS Everywhere.


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Petter Häggholm

April 2016

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