Twitter is looking to add another layer of protection to its user authentication. After at least 250,000 account passwords were compromised in an attack against its service last week, Twitter apparently plans to implement two-factor authentication as an option to help users better protect their accounts—or at least it's hiring people to help do that.

In a job listing posted by Twitter this week, the company seeks software engineers to develop "user-facing security features, such as multifactor authentication and fraudulent login detection." When contacted by Ars, a representative for Twitter said the company has no specific details to share about its plans at this time.

Twitter currently uses OAuth as its authentication protocol via applications (either mobile apps or other Web services), which prevents attackers from recording and replaying session information trying to hijack open user sessions. For direct user authentication, Twitter uses secure socket layer (SSL) encryption to pass user credentials from Web browsers and other Twitter clients.

Those measures protect users' passwords and sessions from being directly intercepted and taken over in most cases. But they don't guard against "man-in-the-middle" attacks, where a malicious access point or firewall using an SSL proxy intercepts encrypted Web traffic. Hackers have grabbed users' Twitter credentials in the past through malicious webpages using cross-site scripting, e-mail "phishing" attacks, and other means. Last August, for example, the Reuters news service had its Twitter feed taken over by pro-Syrian hackers who pulled the Twitter password from the service's blogging platform.

Two-factor schemes are helpful for preventing password hacking through many of these means, and these can prevent account hacks in cases where passwords themselves are compromised—like the case of last week's Twitter breach. Currently, Google and Microsoft have forms of two-factor authentication for their services, using text messages sent to a "trusted" mobile device to confirm logins from previously unknown devices or IP addresses. Google also allows for users to print out "one-use" codes to carry with them to authenticate themselves at new locations or devices without a phone.

But two-factor authentication isn't a cure-all for user security. For example, in the case of Wired's Mat Honan, attackers were able to use information available publicly to convince Apple they were Honan so they could "recover" his account and reset his AppleID passwords. Hackers gained access to his Twitter accounts and Gizmodo's Twitter account in the process. Account recovery allows users to use an e-mail address to reset their account information if they have lost or forgotten their password, but it also allowed the hackers to gain access to Honan's Gmail account, as his alternate account was his Apple e-mail address.

Listing image by Shawn Campbell