The Rules of Engagement (RoE) document is crucial when there's a dispute or issue with accepting a penetration test report. The RoE outlines the scope, methods, timing, legal considerations, and objectives of a penetration test. It serves as a guideline for both the client and the testing team on what is expected and permissible during the assessment. If there are issues with the report, referring back to the agreed-upon RoE can clarify whether the test was conducted within the agreed parameters and help resolve any disputes.
The signed authorization letter, statement of work, and non-disclosure agreement are also important documents but are more related to the permission, scope of work, and confidentiality aspects of the engagement, respectively, rather than the specifics of how the test was to be conducted, which is what the RoE covers.