Reviewing a vendor's security without a hundred-question spreadsheet
Threat modeling is a structured process to analyze system security from an adversarial perspective, according to OWASP Threat Modeling Cheat Sheet.
A thorough security review doesn't require an exhaustive checklist. Instead, verify that a vendor has integrated fundamental, high-impact security practices into their development lifecycle. This approach is more effective than a static questionnaire because it evaluates their security posture as a living process.
Look for evidence of threat modeling
A vendor should be able to describe how they systematically identify security threats during design. Threat modeling is a structured, repeatable process used to gain actionable insights into the security characteristics of a particular system by analyzing it from an adversarial perspective (OWASP Threat Modeling Cheat Sheet). The process should answer four key questions: what is being built, what can go wrong, what will be done about it, and whether the job was done well enough.
A common technique is STRIDE, which categorizes threats—Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, and Elevation of Privilege—to ensure a comprehensive review (OWASP Threat Modeling Cheat Sheet). For cloud-native systems, ensure their modeling accounts for shared responsibility models, managed service APIs, and dynamic infrastructure.
Verify they manage third-party dependencies
Modern applications rely heavily on external libraries, making dependency management a critical security control. A vendor must have an automated process to detect vulnerable third-party dependencies from the start of a project, as adding this later can impose a huge burden (OWASP Vulnerable Dependency Management Cheat Sheet).
Ask about their process when a vulnerability is found. A mature vendor follows a decision tree: updating to a patched version is the first response. If a patched version isn't available, they should implement protective code or workarounds. If the provider will not fix the issue, the vendor may need to patch the dependency themselves or find an alternative (OWASP Vulnerable Dependency Management Cheat Sheet).
Align with high-impact baseline goals
Use established baselines to frame your evaluation. The Cross-Sector Cybersecurity Performance Goals (CPGs) from CISA provide a voluntary set of high-impact practices aimed at meaningfully reducing risks, serving as an excellent benchmark for critical infrastructure entities (CISA Cross-Sector Cybersecurity Performance Goals). These goals are designed to help organizations prioritize a limited number of essential actions with known risk-reduction value.
The CPGs consider not only risk to the individual entity but also aggregate risk to the nation, and they are aligned with the NIST Cybersecurity Framework 2.0 (CISA Cross-Sector Cybersecurity Performance Goals). Asking how a vendor's practices map to these or similar frameworks can reveal the maturity and prioritization of their security program.
Frequently asked questions
Can I just rely on a SOC 2 report?
A structured threat modeling process is something that should be maintained, updated and refined alongside the system (OWASP Threat Modeling Cheat Sheet).
What if the vendor is a small company?
The scale of the process can be adapted. Threat modeling can begin with techniques like brainstorming and whiteboarding, and the CISA CPGs are specifically aimed at helping small- and medium-sized organizations kickstart their cybersecurity efforts (CISA Cross-Sector Cybersecurity Performance Goals). The key is the presence of a deliberate, repeatable approach.
How do I handle a vendor that uses many cloud services?
Ensure their threat modeling adapts to cloud architectures. For cloud-native systems, the threat modeling process should account for shared responsibility models, managed service APIs, and dynamic infrastructure like serverless functions (OWASP Threat Modeling Cheat Sheet). Frameworks like the AWS Well-Architected Framework – Security Pillar can serve as a reference.
What's the most common mistake in dependency management?
Adding automated dependency analysis late in a project lifecycle. It is highly recommended to perform automated analysis of the dependencies from the birth of the project to avoid a huge amount of remediation work later (OWASP Vulnerable Dependency Management Cheat Sheet).
Where to start
Sources
- raw.githubusercontent.com
- Cross-Sector Cybersecurity Performance Goals | CISA
- raw.githubusercontent.com
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_Researched with AI assistance from a live passive security scan run by NEL (scan eph_mtl35v4d_d), which was not retained; citing 3 external sources; 12 factual claims were extracted and checked against their sources (12 of 12 verified); each verification step was independently recorded and signed by Vitna, which attests that the check ran and what its verdict was — not that the underlying claim is true (records b18debc2-9c90-4636-bbc2-dba33cea2541, ddcadb36-7de9-40ce-86ab-c5fe0c65bd8c, 175e3d6c-4327-44e6-9265-fd8b18325751, +40 more, verify at https://vitna.costrinity.xyz/api/evidence/verify); released automatically after every check above passed; not reviewed by a human before publication; published by NEL Professionals with no individual byline._
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