Episode 22 — Define Security Requirements for Acquisitions That Vendors Can Actually Meet
In this episode, we ease into a part of security engineering that quietly shapes everything downstream: how you write security requirements when you are buying a product or service instead of building it yourself. New learners often picture requirements as strict rules you throw over the wall, but in real acquisitions, requirements must do two jobs at the same time. They must protect the organization’s security needs, and they must be realistic enough that a vendor can understand them, price them, and deliver them without turning the project into a long argument. If the requirements are vague, vendors will promise the world and deliver confusion, and if the requirements are impossible, vendors will either walk away or pretend they can do it and then fail later. The skill you are building here is learning to write security requirements that are clear, testable, and achievable, so the acquisition results in something you can actually operate and defend.
Before we continue, a quick note: this audio course is a companion to our course companion books. The first book is about the exam and provides detailed information on how to pass it best. The second book is a Kindle-only eBook that contains 1,000 flashcards that can be used on your mobile device or Kindle. Check them both out at Cyber Author dot me, in the Bare Metal Study Guides Series.
A good requirement starts with a clear problem statement, even if that problem statement is only implied in the way you write. The organization is not buying security in the abstract; it is buying a system that will handle data, support a mission, and interact with people and other systems. Security requirements should therefore be tied to what the system needs to protect, what could go wrong, and what level of assurance is needed for the context. For a beginner, it helps to separate needs from solutions, because needs describe outcomes and constraints while solutions describe specific products or technical designs. A requirement like the system must protect sensitive records from unauthorized disclosure is a need, while a requirement like the system must use a specific encryption product is a solution. Vendors can meet needs in multiple ways, but they cannot fairly compete when you force one design, and you also risk locking yourself into choices you do not fully understand yet.
One of the biggest mistakes in acquisition requirements is writing requirements that sound impressive but cannot be verified. If you say the vendor must provide enterprise-grade security or military-level encryption, those phrases may feel strong, but they do not tell anyone what to build, what to configure, or how to test. A vendor can claim compliance with a vague phrase, and you will have no clean way to prove whether the claim is true when the system arrives. A good requirement is measurable in some way, even if the measurement is a process check rather than a technical metric. For example, requiring that the vendor provide documented security architecture artifacts, a vulnerability disclosure process, and evidence of patch release practices creates something you can check. Verifiable requirements prevent disagreements later because they turn opinions into observable evidence.
To keep requirements realistic, you need to understand what vendors typically control and what they do not. A cloud service provider can often control the security of their infrastructure and platform, but the customer controls how identities are managed, how data is classified, and what user behaviors are allowed. A software vendor can deliver secure code and features, but the customer may be responsible for configuration, user provisioning, and ongoing monitoring. If you write requirements that assign responsibilities to the wrong party, the vendor may respond with a proposal that looks compliant but includes fine print saying the customer must do most of the work. That is not automatically bad, but it must be explicit, because hidden shared responsibility leads to gaps. A realistic set of requirements makes ownership clear, so everyone knows which security outcomes the vendor must deliver and which outcomes the organization must deliver.
A strong technique for beginners is to think in terms of security capabilities rather than security promises. Capabilities are things the product or service can do that support your policies and risk decisions. Examples of capabilities include producing reliable audit logs, supporting strong authentication options, enabling role-based access control, and allowing data to be encrypted in storage and in transit. These are not implementation steps, but they are concrete enough that a vendor can respond clearly. Capabilities also let you compare vendors fairly, because you can ask each one how they support the capability, what is included, and what is an add-on. When requirements are capability-based, you reduce the chance of buying something that sounds secure but cannot support the controls you need when you actually deploy it.
Another key idea is to separate mandatory requirements from desired features, even if you never label them that way in your documents. If everything is written as a must, vendors will either inflate cost, refuse to bid, or claim compliance without meaningful commitment. Realistic acquisition language uses must statements for items that are truly non-negotiable for risk acceptance, and then uses flexible language for items that are preferences or future goals. This does not weaken security; it strengthens it by clarifying what matters most and avoiding a situation where vendors focus on the wrong details to appear compliant. A practical way to decide what is truly mandatory is to ask whether you would accept the system if the item were missing, and if the honest answer is no, then it belongs in the non-negotiable category. Requirements become more achievable when they reflect true priorities rather than wish lists.
Security requirements also need to account for the full lifecycle of the acquisition, not just the day the system goes live. A product that is secure on day one but cannot be patched safely, cannot be monitored, or cannot be supported under your operational constraints becomes insecure over time. Requirements should include expectations for vulnerability management, patch cadence, end-of-support timelines, and how security updates are communicated. They should also address what happens when the vendor discovers a security flaw, including how quickly they will notify customers and what mitigation guidance they will provide. These items are often easier for vendors to meet than very specific technical controls, because they fit into mature development and support practices. They also have a direct impact on your ability to manage risk after deployment, which is a major concern for any secure system.
You should also include requirements that make evaluation and acceptance possible, because a requirement you cannot test is a requirement you cannot enforce. Acceptance criteria can be technical, such as demonstrating that logs include certain fields, or procedural, such as providing a security test report or a penetration testing summary performed by a qualified third party. The important beginner lesson is that acceptance is not only about whether the system works, but whether the security controls work as intended in your environment. Vendors often test in their own lab conditions, so your requirements should reflect that the system must operate securely under the conditions you will actually use, such as your identity provider, your network boundaries, or your data handling rules. This is not about telling the vendor exactly how to build, but about making sure the delivered system can be validated in a way that matches your real risk.
When writing requirements that vendors can meet, clarity of language matters as much as technical content. Words like secure, robust, and adequate are open to interpretation, and different vendors will interpret them in ways that benefit their proposals. Instead, use plain statements that specify who does what, what evidence will be provided, and what conditions must hold true. For example, rather than saying the system must have strong access controls, you can describe the expected control outcome, such as supporting least privilege through configurable roles and separating administrative functions from regular user functions. Clear language reduces surprises and makes the contract relationship healthier because fewer expectations are left unspoken. It also helps non-technical stakeholders understand what is being purchased, which matters when the acquisition is reviewed by leadership or oversight bodies.
A crucial part of realism is understanding that vendors sell products, not perfect security, and every product has limitations that must be managed. That is why requirements should include disclosure of known limitations, constraints, and dependencies, because you need to know what assumptions the product makes about its environment. If a vendor solution assumes all administrators will be carefully trained and never reuse passwords, that assumption must be surfaced because it is a risk factor. If a service assumes it will have outbound network access to certain endpoints, that dependency affects your architecture and monitoring. When vendors can openly describe constraints without being punished, you get a more truthful proposal, and you can plan compensating controls where needed. Realistic requirements create space for honest limitation disclosure while still protecting the organization’s baseline security expectations.
Another common pitfall is copying large control catalogs into a requirements document without tailoring them to the acquisition. Control catalogs are useful references, but vendors respond better to tailored requirements that map to the system’s role and your environment’s needs. If you paste dozens of controls that are irrelevant, vendors may respond with generic compliance statements, and you will waste evaluation effort on noise. Tailoring means selecting the control outcomes that actually matter for the acquisition, then expressing them in language that fits the product and its delivery model. For example, a managed service might meet monitoring requirements through their operations center, while a software product might meet them by generating events your monitoring system can ingest. Tailoring keeps the requirement set both stronger and more achievable because it aligns with how the vendor can realistically deliver value.
You also need to think about how requirements affect competition, because acquisitions often depend on having multiple vendors able to bid. If requirements accidentally describe one vendor’s unique feature set, you may narrow the field and raise cost without improving security. Fair requirements describe what must be achieved, not which brand, platform, or proprietary approach must be used. This is not only a procurement concern; it is a security concern, because fewer options can mean weaker negotiating leverage on security commitments and support terms. A balanced requirement set improves both security and outcomes by encouraging vendors to propose strong solutions while still meeting your essential constraints. The best requirement sets create a clear minimum bar and then allow vendors to differentiate through better assurance, better transparency, or better operational fit.
Finally, the way you communicate requirements matters, because vendors need to understand the why behind the requirements to respond intelligently. When vendors see requirements as arbitrary hurdles, they look for the easiest way to claim compliance, but when they understand the risk context, they can offer designs and evidence that match your true needs. That does not mean you hand them your entire internal threat model, but it does mean you provide enough context about data sensitivity, mission impact, and operating environment. With context, vendors can propose realistic levels of logging detail, access control structure, and support commitments that match the acquisition. Without context, you get generic answers and later you discover mismatches during integration or testing. The mature skill is balancing context with confidentiality while still making the requirements understandable and actionable.
The most important takeaway is that security requirements for acquisitions should be written so they can be understood, priced, delivered, and verified, because that is how you avoid buying a security story instead of a secure capability. Requirements that are too vague create loopholes, requirements that are too rigid create failure and resentment, and requirements that are too broad create noise that hides what matters. When you focus on clear outcomes, shared responsibility, lifecycle support, and testable acceptance criteria, you create a requirement set vendors can actually meet and leaders can actually defend. As you continue learning, keep practicing the mindset that a requirement is a promise you intend to check, not a wish you hope comes true. That discipline is what turns acquisitions into dependable security outcomes rather than expensive surprises.
