How to Identify Known CVEs in Closed-Source Firmware Without Source Code

Security researchers working with embedded and IoT devices often face the challenge of auditing closed-source firmware binaries for known vulnerabilities without access to vendor source code. The recommended approach begins with unpacking firmware images using tools like binwalk to extract the underlying filesystem, followed by scanning binaries for version strings using the 'strings' command. Identified component versions can then be cross-referenced against CVE databases using automated tools such as CVE-bin-tool, which matches findings against NVD vulnerability data. For kernel modules lacking readable version banners, utilities like modinfo and reverse engineering tools such as Ghidra can help narrow down applicable vulnerabilities. Crucially, a version match should be treated as a lead rather than a confirmed finding, since vendors sometimes backport fixes without updating version strings.