ISSA Security Awareness Column August 2012 – Security Satisficing

What if much of our security advice to users was a waste of their time? What if some of it actually made users worse off? These are bold words but stay with me and let’s see where this goes. There will be some maths on the journey but it will be worth it I promise. Let’s look at passwords as an example. Many thousands of pages of security policy have been generated on creating strong passwords. It’s one of the most common subjects for security awareness. More letters, more numbers, make it longer and put a special character in it. Actually, most passwords don’t need to be strong, they just need to be difficult to guess which isn’t the same thing. Cormac Herley points out that password strength no longer has the critical role in security that it used to. It’s largely irrelevant since most systems now control the rate of password guessing attempts. For example only allowing five attempts every 30 minutes. In this scenario, the difference between 7 character and 8 character passwords is negligible if the system limits a brute force attack to 240 attempts per day. Modern authentication systems are much more likely to be compromised by password database disclosures, password re-use and key-loggers. Complexity does not assist with managing any of these threats. For years we’ve been focused on complexity and as a result users come up with combinations like “Password1” which meet our complexity rules but don’t effectively mitigate their risks. We need to change. We need to stop talking about password complexity and start talking about password commonality. Potentially, we’re doing more harm than good by occupying valuable (and limited) attention spans with topics of marginal return. The risks have changed and our risk communication needs to reflect that.