Client-Side Commercial Vendor Discovery
Client-Side Commercial Vendor Discovery is a reconnaissance sub-technique within Application Dependencies Mapping where attackers analyze traffic and available application binaries (across mobile, desktop, and on-prem environments) to identify third-party commercial software vendors in use. By examining network communications, API calls, embedded libraries, certificates, and binary signatures, adversaries can map the commercial software ecosystem supporting the target application. Furthermore, the presence of a known commercial vendor can signal a potential pivot point within the software supply chain, especially if the vendor is less mature or trusted implicitly via integration than the intended target. In parallel, public OSINT sources (e.g. marketing materials, case studies, job postings, or SOC 2 reports) can reveal formal relationships between a company and specific vendors, providing additional context for targeted exploitation.
Identifying commercial vendor integrations enables an attacker to keep the primary target in focus while exploiting the vendor as a weaker entry point. By leveraging trust relationships, exposed credentials, or insecure integration patterns, the attacker can gain indirect access to the target environment through a secondary target, bypassing potentially stronger front-line defenses. This technique is particularly effective because organizations often apply more rigorous security controls to their primary systems while treating vendor integrations as trusted third-party components with reduced scrutiny.
Mitigations
| ID | Mitigation | Description |
|---|---|---|
| M1013 | Application Developer Guidance | Use subresource integrity (SRI) and self-host critical vendor scripts to avoid disclosing CDN URLs that reveal technology stack. |
| M1021 | Restrict Web-Based Content | Obfuscate or bundle third-party JavaScript/CSS to limit passive fingerprinting of commercial SDK versions. |
Detection
Client-side vendor discovery happens within the attacker’s browser via public asset inspection and cannot be observed from inside the target environment.
After-the-fact clues may include:
- Web-server logs showing unusually deep enumeration of static asset directories (
/static/js/*, plugin lists) from unfamiliar IP ranges. - Threat-intel reporting on mass fingerprinting campaigns enumerating specific CMS or analytics SDK versions.
- Tailored exploits or phishing that reference proprietary vendor-script details gleaned during the inspection phase.