The threat gets a vote

The threat gets a vote

“The enemy gets a vote”

“Organizations often blame the end user who clicked the link. What about the actions taken after the initial click? This scenario indicates an organization’s entire security model may depend on users not clicking a link in an email. The organization does not intend to hinge all security on a single user, but the actions taken to defend their systems often say otherwise.”

Threat Gets A Vote: Applying a Threat Based Approach to Security Testing via Instapaper

How long is a piece of string?

Pop quiz:

If I need to secure something with a password, how long should that password be?

a) Three digits ("326")
b) 12 characters, alphanumeric and symbols ("JasperTato!7")
c) 32 hexadecimal characters ("41c9db4d3674590033790f6924be64ad")

Of course, this is a trick question: the correct answer is that it depends on what you’re trying to secure, and who you’re trying to secure it from.

Know your threat model

In very simple terms, a threat model is a combination of two pieces of knowledge:

  1. What you are trying to protect from attack
  2. What sort of person is likely to attack it

One example: I have a medicine cupboard at ground-level in my house, and I want to prevent my children from accessing it. I decide to use a combination lock with a three-digit code (answer ‘a’ above).

Another: I need a password to protect my personal email account, and I want to prevent hackers from trivially guessing it. In this case, I decide to use a 12 character password (answer ‘b’).

Finally: I need to encrypt a file for 20+ years, and I need it to be secure from even a government agency with access to billions of dollars worth of computing power. Along with a good encryption method, I use a 32-character alphanumeric password (answer ‘c’).

The differences in these answers seem obvious, because we tend to do basic threat modelling intuitively. Obviously I shouldn’t use a 3-digit code for my email account (even if the service allowed me to). Obviously I don’t need a 12+ character password protecting the medicine cupboard. Obviously neither of these is likely to be good enough against the NSA.

We’ve made a compromise between convenience and security, without really thinking about it.