Reflected or stored cross-site scripting
Attacker-controlled input executes in another controlled user’s browser under the application origin.
Candidate CWE: CWE-79
Test hypothesis#
Locate the HTML, attribute, or script context with a text marker. In a private shared fixture, use a context-appropriate benign DOM-marker payload and verify execution from B’s normal viewing workflow.
Evidence required#
The affected origin executes the marker in B’s browser without manual DevTools execution. Preserve source input, delivery path, sink, browser context, and cleanup.
Rule out false positives#
Reflection without execution, self-XSS requiring console paste, execution only in an isolated untrusted origin, or CSP-blocked payloads do not prove the claimed impact.
Playbook and command references#
- Browser execution, cross-origin reads, and forged actions — Use real browser behavior to distinguish XSS, CSRF, CORS, and messaging failures from header-only leads.
- Uploads, downloads, paths, archives, and XML — Follow a file through acceptance, storage, processing, publication, and retrieval while preserving ownership and path boundaries.
Find the associated command snippets
Referenced by these target playbooks#
Report checklist#
- Capture the affected version, configuration, identities, and object ownership.
- Preserve a valid baseline and a negative control.
- Reproduce the forbidden data access, action, or state change on controlled fixtures.
- Explain the intended security rule and why the observed behavior violates it.
- State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.
Conditional ATT&CK mapping#
- T1539 · Steal Web Session Cookie — Only if: The tested weakness exposes an authentication session cookie across a boundary, for example from a controlled victim browser or improperly protected storage. Not established by: XSS alone does not prove cookie theft, especially when the relevant cookie is HttpOnly. Cookie acquisition and successful session replay are distinct evidence steps.