attack-surface.md

Attack Surface Analysis for mwaterfall/mwphotobrowser

Attack Surface: Cross-Site Scripting (XSS) via Configuration

• Description: Injection of malicious JavaScript code into the web page through application configuration options that are rendered by mwphotobrowser. This occurs when unsanitized user-controlled data is used in configuration options like caption or description.
• How mwphotobrowser contributes: mwphotobrowser directly renders configuration options, including caption and description, into the DOM. If the application provides unsanitized data to these options, mwphotobrowser will render it as HTML, potentially executing injected JavaScript.
• Example: An attacker injects <img src=x onerror=alert('XSS')> into an image caption field in the application. If the application passes this unsanitized caption as the caption option to mwphotobrowser, the JavaScript alert('XSS') will execute when mwphotobrowser renders the image display.
• Impact: Full compromise of the user's browser session, including stealing cookies, session tokens, redirecting to malicious websites, defacement, and potentially further attacks against the user's system.
• Risk Severity: High
• Mitigation Strategies:
  • Input Sanitization: The application must sanitize all user-provided data before using it in mwphotobrowser configuration options (especially caption, description, and any URL-based options). Use robust HTML escaping or sanitization libraries to neutralize potentially malicious JavaScript code before passing data to mwphotobrowser.
  • Content Security Policy (CSP): Implement a strict Content Security Policy to limit the sources from which the browser can load resources and execute scripts. This acts as a secondary defense to mitigate the impact of XSS even if input sanitization is bypassed.

Attack Surface: DOM-based XSS through Image Attributes

• Description: XSS vulnerability arising from mwphotobrowser's manipulation of the Document Object Model (DOM) when setting image attributes (like alt or title) using data from potentially untrusted sources.
• How mwphotobrowser contributes: If mwphotobrowser dynamically sets image attributes based on configuration data originating from user input or untrusted sources without proper encoding, it can introduce DOM-based XSS. mwphotobrowser's code is responsible for setting these attributes in the DOM.
• Example: The application uses a user-provided description as the alt attribute for images displayed by mwphotobrowser. If the description contains <img alt="Attacker's payload" onerror=alert('DOM XSS')>, and mwphotobrowser directly sets this as the alt attribute without encoding, the JavaScript alert('DOM XSS') will execute when the browser processes the image tag.
• Impact: Similar to reflected XSS, can lead to browser session compromise, data theft, redirection, and defacement.
• Risk Severity: High
• Mitigation Strategies:
  • Output Encoding: Ensure that data used to set HTML attributes by mwphotobrowser is properly encoded before being inserted into the DOM. Use browser-provided encoding functions or libraries to escape special characters and prevent JavaScript injection within attribute values.
  • Input Validation and Sanitization (Defense in Depth): While output encoding is essential, sanitizing input as a defense-in-depth measure can further reduce the risk. Validate and sanitize user inputs before they are used to configure mwphotobrowser.
  • Regular Security Audits: Review the source code of mwphotobrowser (or the parts you are using and configuring) and the application's integration to verify that proper output encoding is consistently applied when setting DOM attributes.