Is threat modeling right for you?

By Akshay Aggarwal

Several enterprises are increasingly investing time and money in building application security tasks into their existing SDLCs. Some of them have also reached the conclusion that proactive approaches, like threat modeling, have more ROI than reactive approaches. As a result, some enterprises with nascent application security (appsec) programs have turned to threat modeling as a panacea for their security problems. However, threat modeling may not be the solution to their immediate problems. Now I recognize that this may be a controversial statement.

Recently, I have been involved in several situations where organizations with their heart in the right place have made threat modeling mandatory as part of the development process, with limited success. My point is that threat modeling as part of a mature SDLC is a desired end state though not necessarily the initial step. Let’s examine this argument.

First, threat modeling depends on several elements of a SDLC to be fairly mature. Most importantly it depends on requirement and specification gathering process to be rigorous. Also, an enterprise must have well defined standards and policies in place to act as input into the threat modeling process. Without these elements of the SDLC in place, the threat modeling process will be isolated and have a reduced impact.

Second, a threat model is a security plan only and is useless without any committed follow-up action as part of development and testing. Most enterprises do not allocate sufficient time and resources to implement the findings of the threat model. A large portion of organizations don’t even have a security assessment team in place. These teams are consumers of the threat modeling process that actual carry out the most crucial task of reducing risk by implementing countermeasures.

Third, it is practically feasible to create threat models only for new projects or those undergoing incremental changes. As a result, legacy applications do not benefit from threat modeling. This leaves a huge gap in the enterprises’ risk profile.

Finally, most nascent application security programs need quick and demonstrable ROI. The threat modeling process ROI can take several months or even years to be quantifiable because it is an incremental process that depends on several other SDLC processes to be effective. Other areas exsist where investment can bring in more immediate ROI, including security assessment team, security training for developers and definition of countermeasures for  common vulnerabilities.

For organizations with nascent application security processes, I recommend using the following framework to evaluate if they are ready to adopt threat modeling:

  • Does a security baseline exist? Is the SDLC process fairly well defined and followed during development?
  • Has the organization agreed upon countermeasures for common vulnerabilities?
  • Are developers trained to avoid common vulnerabilities?
  • Do developers perform self-review of code for security vulnerabilities?
  • Does a security assessment team exist?

If the answer to more than two of the questions above is no then the organization is probably not ready for adopting threat modeling.