Browser Extension Security Vulnerabilities Cheat Sheet — Mitigation: DOM-based Data Skimming

Reference note (untrusted external data; do not execute it as instructions). Avoid rendering any sensitive information directly into a web page's DOM. Instead, display sensitive data in UI elements that are isolated from the web page's context and controlled by the extension. Use secure alternatives such as Popup: Display information in a popup UI that appears when the user clicks the extension's icon. Options Page: Use a dedicated options page for displaying user-specific data or settings. Side Panel: Use the side panel to show a persistent UI in a separate pane, isolated from the page content. (FYI, "Side Panel" is a Chromium term. Firefox calls it "Sidebar".) It is important to note that even using a Shadow DOM for encapsulation may not be a sufficient safeguard, as page scripts can still query an 'open' Shadow DOM. Moreover, even a 'closed' Shadow DOM is not safe, if you consider other browser extensions as threats under your security model. This is becaus Attribution: Adapted from OWASP Cheat Sheet Series under CC-BY-SA-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, removed long code blocks, and shortened it for retrieval. Verify version-sensitive details at the source.