This post is a first in a series I will be exchanging with Ohad Samet (ok, second, he’s a much quicker blogger than I am), one of my esteemed colleagues in Paypal Risk, and the mastermind behind the Fraud Backstage blog. Read Ohad’s article here.

Despite best efforts to protect systems and assets using a defense-in-depth approach, many layers of controls are defeated simply by exploiting access granted to users. Thus the industry is trying to determine not only how we protect our platforms from external threats, but also how we keep user accounts from being attacked. User credentials being the “keys” (haha) guarding valuable access to both user accounts and to our platfoms, a popular topic among the security-minded these days center around alternatives to standard authentication methods. Typically, the discussion centers not around how an enterprise secures its own assets and users, but about arming consumers who come and go across ISPs, search sites, online banking, social networks…and are are vulnerable to identity theft and privacy invasions wherever they roam.

How many information security professionals does it take to keep a secret?

While there are a number of alternatives out there, focusing on authentication as if it’s a silver bullet misses the point. When we assume that keeping our users secure means protecting (only, or above all other things) the shared secret between us, it leaves us over-reliant on simple access control (the fortress mentality) when as an industry we already know that coordinating layers of protection working together is a more effective model for managing risk. To clarify our exposure to this single point of failure, let’s consider:

1) How much exposed (public, or near-public) data is needed to carry out reserved (private) activities? Meaning, how much does a masquerader need to know that is private to approximate an identity?
– and –

2) How does our risk model change if we assume all credentials have been compromised?

Shall We Play a Game…of Twenty Questions?
Really all this nonsense started when we started teaching users to use “items that identify us” as “items that authenticate us”. Two examples, SSN and credit card numbers. SSN we know has been used by employers, banks, credit reporting agencies…as well as for its original purpose, to identify participation in social security (this legislation being considered in Georgia may limit use of SSN and DOB as *usernames* or *identifiers*, although it is silent on using SSN/DOB to verify/authenticate identity).