Authentication schemes have often been adopted by widely used websites out of convenience, but they've also become a growing source of serious security risks in recent history.  In an open Wi-Fi network a stranger, with the proper tools, can see everything including your authentication token.  With that token they can access your Facebook or Twitter account, with little skill involved.

Such issues were long thought to be constrained to the PC, with programs like Firesheep making exploitation a cakewalk for novice hackers.  However, a weak authentication API (application protocol interface) has landed Google's Android OS as the latest victim of exploits.

Like PCs, Google's API requests a token by sending a password and user name encrypted via a clear http connection.  Since http is used, the response token is broadcast in plaintext over your network connection.  That means that one a public network everyone can see it.

The exploit was just discovered [press release] this week by Bastian Könings, Jens Nickels, and Florian Schaub, a trio of German researchers at the University of Ulm.  They conducted a proof of concept attack, using Wireshark to sniff the packets containing the authentication token from certain Android apps.  They found that any Android version prior to 2.3.4 (the most recent version of Android "Gingerbread") was susceptible.

The exploit affects all first and third party apps that make use of the ClientLogin API.  Apps that use this API for authentication include Facebook, Twitter, and Google's own Calendar app.

It is unknown whether iOS's authentication-dependent APIs are completely secure or whether one or more of them might have similar issues.  But pro-Apple commentators were quick to gloat about this apparent security embarrassment for Android.  Daring Fireball blogger John Gruber takes the opportunity to take a jab at the laggard pace of updates from Android hardware makers and phone carrier, writing:

I’m sure most Android handsets will be updated to version 2.3.4 or later very soon, so no worries.

While the exploit is indeed troublesome, there's still plenty that Android users who don't have the update can do to protect themselves.  First and foremost they can avoid open Wi-Fi networks.

If that's not an option, users can still safeguard themselves with a bit of work.

Android users can simply access Facebook and Twitter via the https versions of the pages in the browser, instead of using the commonly used Android apps.  There shouldn’t be any authentication issues if that approach is taken.

The calendar is a bit more problematic as there's no way to safeguard it.  Android users' best bet is to kill your calendar app when they're on an open connection.

Again these steps are only necessary if you are on an open Wi-Fi connection.

The good news is that Google appears to be moving to fix this issue sooner or later.  It already has enforced mandatory use of https (which does not reveal the authtoken in plain text) in its Google Docs API, and this change is expected to spread to the rest of the authentication-dependent APIs briefly.  Given the press coverage this hack is getting, we're guessing that will pushed out as a patch sooner, rather than later.

Until that patch arrives, follow the above described precautions whenever you're on an open network.

Last fall the iOS was shown to have a bug that gave unauthorized users full access to the phone app via a trick on the unlock screen.  While dangerous, that exploit was a bit different -- it required physical access.  By contrast this exploit doesn't even require a hacker to touch your Android handset.