I’ve read a number of articles about account security, passwords and secret questions this week for obvious reasons. Although I’ve seen a number of posts directed at end users as to how to better safeguard their accounts, I haven’t seen anything similar providing guidance to developers of online services on how to better safeguard their users in what is a very hostile environment.
Below are the top five (plus a bonus one) account security features that every competent online service should have implemented. None of these are ground breaking but it is quite clear that many services that we all use every day don’t implement even these basic security features thus putting our data at risk.
Analysis of these lists show that people are quite predictable and you often find "password", "abc123", "letmein" or the name of the website being used by a sizable percentage of the users on your site. It thus makes sense to ban users from using any of these fairly common passwords which can then lead to successful drive-by hacking incidents. For example, a hacker can take the basic approach of trying to log-in to a bunch of users accounts using "password", "123456" as their email address and if past history is a judge can end up compromising thousands of user accounts with just this brain dead tactic.
Throttling failed password attempts: Regardless of how strong a user’s password is, it is trying to stop a bullet with a wet paper towel against a dedicated brute force attack if no protections are in place. Password cracking tools like John the Ripper can crack a strong eight character password in about 15 minutes. This means to fully protect users, online services should have a limit on how often a user can fail a password challenge before you put some road blocks in their way. These road blocks can include exponentially increasing delays after each failed attempt (wait 1 minute, if failed again then 2 minutes, etc) or requiring the person to solve a CAPTCHA to prove they are human.
Another thing services should do is look at patterns of failed password attempts to see if broader prevention strategies are necessary. For example, if you are seeing hundreds of users failing multiple password attempts from a particular IP range you may want to block that IP range since given our previous discussion about weak passwords they probably have successfully hacked some of your accounts.
2-factor authentication: Every online service should give customers the option to trade convenience (i.e. password only sign in) with more security. Two-factor authentication is typically the practice of combining something the user knows (e.g. a password) with something the user has (e.g. their smart phone or biometric data). Although more inconvenient than just providing a password, it greatly increases the security for users who may be desirable targets for account hijackings or when providing a service that holds sensitive data. This is why it is supported by a number of popular online service providers including Google, Microsoft and Twitter.
A common practice to improve the usability of 2-factor authentication is to give users the option to only require it the first time the sign-in from a particular device. This means that once the user goes through the two step authentication process from a new computer, you can assume that that device is safe and then only require a password the next time they sign in from that device.
Choose better secret questions or better yet replace them with proofs: Inevitably, users will forget the password they use with your service especially if you require strong passwords and have a policy that is incompatible with their default password choice (which hopefully isn’t “password1” ). A common practice, which has now become an Achilles heel of account security, is to have a set of back up questions that you ask the user if they have forgotten their password. The problem for account security is that it is often easier to guess the answers to these questions than it is to hack the user’s password. There is a great check list for what makes a good secret question at goodsecurityquestions.com with examples of good, fair and poor security questions.
In general you should avoid security questions because most can be easily guessed such as what is your favorite color or sports team and for others their answers can be easily found on Facebook such as where the user went to high school or via social engineering your friends. A much better approach is to use a similar approach to 2-factor authentication where a user provides proof of something they have such as their smartphone (send an SMS) or alternate email account (send an email) to verify that they are who they say they are.
Show customers their sign-in activity: When all else fails, it is important to give your customers the tools to figure out for themselves if they have been hacked. A good way to do this is to let them know of sign-in attempts that have occurred on their account so they can that either failed or were successful. Google does this today via its last account activity feature. You can find this by going to security.google.com and click Recent activity under “Security” on the left. Microsoft provides this with its recent activity feature which you can find by going to https://account.live.com/activity.
Implementing these features isn’t a cure all for account security woes and should instead be treated as the minimum bar for providing a reasonable level of security for your users.
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