Tag Archives: application security

DevSecOps Decisioning Principles

I know you’ve heard this before, but DevOps is not about tools. At its core, DevOps is really a supply chain for efficiently delivering software. At various stages of the process, you need testing and validation to ensure the delivery of a quality product. With that in mind, DevSecOps should adhere to certain principles to best support the automated SDLC process. To this end, I’ve developed a set of fundamental propositions for the practice of good DevSecOps.

  • Security tools should integrate as decision points in a DevOps pipeline aka DevSecOps.
  • DevSecOps tool(s) should have a policy engine that can respond with a pass/fail decision for the pipeline. 
    • This optimizes response time.
    • Supports separation of duties (SoD) by externalizing security decisions outside the pipeline.
    • “Fast and frugal” decisioning is preferred over customized scoring to better support velocity and consistency. 
    • Does not exclude the need for detailed information provided as pipeline output.
  • Full inspection of the supply chain element to be decisioned, aka “slow path,” should be used when an element is unknown to the pipeline decisioner. 
  • Minimal or incremental inspection of the supply chain element to be decisioned, aka “fast path,” should be used when an element is recognized (e.g. hash) by the pipeline decisioner.
  • Decision points should have a “fast path” available, where possible, to minimize any latency introduced from security decisioning.
  • There should be no attempt to use customized risk scores in the pipeline. While temporal and contextual elements are useful in reporting and judging how to mitigate operational risk, attempts to use custom scores in a pipeline could unnecessarily complicate the decisioning process, create inconsistency and decrease performance of the pipeline.  
  • Security policy engines should not be managed by the pipeline team, but externally by a security SME, to comply with SoD and reduce opportunities for subversion of security policy decisions during automation.

Using a master policy engine, such as the Open Policy Agent (OPA), is an ideal way to “shift left” by providing a validation capability-as-a-service that can be integrated at different phases into the development and deployment of applications. Ideally, this allows the decoupling of compliance from control, reducing bottlenecks and inconsistency in the process from faulty security criteria integrated into pipeline code. By using security policy-as-code that is created and managed by security teams, DevSecOps will align more closely with the rest of the SDLC. Because at the end of the day, the supply chain is only as good as the product it delivers.

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Moving Appsec To the Left

After spending the last year in a Product Security Architect role for a software company, I learned an important lesson:

Most application security efforts are misguided and ineffective.

While many security people have a good understanding of how to find application vulnerabilities and exploit them, they often don’t understand how software development teams work, especially in Agile/DevOps organizations. This leads to inefficiencies and a flawed program. If you really want to build secure applications, you have to meet developers where they are, by understanding how to embed security into their processes.

In some very mature Agile organizations, application security teams have started adding automated validation and testing points into their DevOps pipelines as DevSecOps (or SecDevOps, there seems to be a religious war over the proper terminology) to enforce the release of secure code. This is a huge improvement, because it ensures that you can eliminate the manual “gates” that block rapid deployment. My personal experience with this model is that it’s a work-in-progress, but a necessary aspirational goal for any application security program. Ultimately, if you can’t integrate your security testing into a CI/CD pipeline, the development process will circumvent security validation and introduce software vulnerabilities into your applications.

However, this is only one part of the effort. In Agile software development, there’s an expression, “shifting to the left,” which means moving validation to earlier parts of the development process.  While I could explain this in detail, DevSecOps.org already has an excellent post on the topic. In my role, I partnered with development teams by acting as a product manager and treating security as a customer feature, because this seemed more effective than the typical tactic of adding a bunch of non-functional requirements into a product backlog.

A common question I would receive from scrum teams is whether a security requirement should be written as a user story or simply as acceptance criteria. The short answer is, “it depends.” If the requirement translates into direct functional requirements for a user, i.e. for a public service, it is better suited as a user story with its own acceptance criteria. If the requirement is concerned with a back-end service or feature, this is better expressed as acceptance criteria in existing stories. One technique I found useful was to create a set of user security stories derived from the OWASP Application Security Verification Standard (ASVS) version 3.0.1 that could be used as a template to populate backlogs and referenced during sprint planning. I’m not talking about “evil user stories,” because I don’t find those particularly useful when working with a group of developers.

Another area where product teams struggle is whether a release should have a dedicated sprint for security or add the requirements as acceptance criteria to user stories throughout the release cycle. I recommend having a security sprint for all new or major releases due to the inclusion of time-intensive tasks such as manual penetration testing, architectural risk assessments and threat modeling. But this should be a collaborative process with a product team and  I met regularly with product owners to assist with sprint planning and backlog grooming. I also found it useful to add a security topic to the MVS (minimum viable solution) contract.

I don’t pretend to have all the answers when it comes to improving software security, but spending time in the trenches with product development teams was an enlightening experience. The biggest takeaway: security teams have to grok the DevOps principle of collaboration if we want more secure software. To further this aim, I’m posting the set of user security stories and acceptance criteria I created here. Hopefully, it will be the starting point for a useful dialogue with your own development teams.

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