A useful domain-purchase chat shows the right documents to the right person. A polished interface cannot replace a check of who can read messages and download attachments. DESCRIBE THE CONVERSATION FIRST For each conversation, identify the buyer, domain or order and the permitted seller staff. A proposed test sequence is buyer A opening their dialogue, buyer B trying the same address, a staff member without messaging permission checking access, and the conversation closing. Write the expected outcomes before running it. Use synthetic documents, not real identity or financial records. Include an owner for investigating each failed expectation so that the checklist leads to action. CHECK EVERY OPERATION OWASP recommends server-side authorization rather than relying on hidden interface controls. Apply this to history retrieval, message submission, attachment upload and obtaining a download link. A conversation ID in a URL is not permission. Repeat checks after a role change and session expiry. A closed conversation can remain readable, but define explicitly whether it accepts new messages. Test direct requests as well as the normal interface. MINIMIZE WHAT PEOPLE EXCHANGE Ask for information needed for the particular transfer step. A simple question about a domain name can stay a text message. Registrar passwords and one-time sign-in codes should not be part of correspondence. When a document contains unnecessary details, ask for a reduced copy before uploading it instead of exposing a complete copy through a public link. Keep instructions short enough for a buyer to understand what is required and why. HANDLE ATTACHMENTS AS A WORKFLOW Define allowed formats and a size boundary. Inspect actual file content rather than trusting its name. After authorization, serve documents through a controlled private mechanism instead of permanent public URLs. Assign responsibility for file checks, errors and retention. For a practical exercise, use an innocuous PDF representing a fictional transaction and an image without personal data. Record whether upload, inspection and download each completed. TEST THE INTERFACE TOO Switch rapidly between two test conversations and make sure old messages never appear under the new domain heading. Check send progress, network failure and refresh after returning to the tab. A read indicator needs a defined event, not an assumption. Secure exchange is a comprehensible process with tested boundaries, not a decorative padlock. Domain catalogue: https://domainevery.com/en/domains Primary sources: https://cheatsheetseries.owasp.org/cheatsheets/Authorization_Cheat_Sheet.html https://cheatsheetseries.owasp.org/cheatsheets/File_Upload_Cheat_Sheet.html
