Skip to content

Latest commit

 

History

History
89 lines (71 loc) · 5.76 KB

attack-tree.md

File metadata and controls

89 lines (71 loc) · 5.76 KB

Attack Tree Analysis for thoughtbot/bourbon

Objective: To degrade the user experience, inject malicious styles, or cause denial-of-service (DoS) conditions within the application by exploiting vulnerabilities or misconfigurations in the Bourbon library or its usage.

Attack Tree Visualization

[Attacker's Goal: Degrade UX, Inject Malicious Styles, or Cause DoS]
    |
    -------------------------------------------------
    |								|
    [Exploit Bourbon Mixin/Function Vulnerabilities]		 [[4. CSS Injection]]
    |								|
    -------------------------					   -----------------
    |								|
[[1. Input Validation Issues]]					  [[4a. Injecting
    |								Malicious CSS via
    -------------------------					   Mixins]]
    |
[1a. Unsanitized User Input to Mixins/Funcs]

Attack Tree Path: [[1. Input Validation Issues]] (Critical Node)

  • [[1. Input Validation Issues]] (Critical Node): This is the root cause of the most significant threat. Bourbon mixins and functions, like any code that accepts input, can be vulnerable if that input isn't properly handled.

    • Description: The core issue is the lack of, or insufficient, sanitization or validation of user-provided data before it's used within Bourbon mixins or functions. This allows an attacker to inject malicious CSS code.
    • Likelihood: Medium-High. Developers often overlook or underestimate the importance of input validation, especially in contexts they perceive as "safe" (like CSS).
    • Impact: High. Successful CSS injection can lead to a variety of attacks, including website defacement, data exfiltration, phishing, and even browser crashes.
    • Effort: Low-Medium. Exploiting this vulnerability typically involves crafting malicious input strings. Tools and techniques for CSS injection are readily available.
    • Skill Level: Medium. Requires understanding of CSS syntax, how Sass variables are used, and common injection techniques.
    • Detection Difficulty: Medium. Requires careful code review, input validation testing, and potentially monitoring of generated CSS. Obvious injections are easy to spot, but subtle ones can be hidden.

Attack Tree Path: 1a. Unsanitized User Input to Mixins/Funcs (Critical Node)

*   **1a. Unsanitized User Input to Mixins/Funcs (Critical Node):** This is the specific mechanism of the vulnerability.

    *   **Description:** User-supplied data (e.g., from form fields, URL parameters, or even data stored in a database) is passed directly into a Bourbon mixin or function without being properly escaped or validated. This allows the attacker to inject arbitrary CSS code.
    *   **Example:**
        ```scss
        // Vulnerable Sass code
        @mixin my-mixin($color) {
          .element {
            color: $color;
          }
        }

        // Attacker input (in a URL parameter, for example):
        // ?color=red;%20}body{background-image:url(http://attacker.com/evil.jpg);}%20/*

        // Resulting CSS (after Sass compilation):
        .element {
          color: red; } body{background-image:url(http://attacker.com/evil.jpg);} /*;
        }
        ```
        In this example, the attacker has injected a `background-image` property that applies to the entire `body`, potentially loading a malicious image or tracking the user.
    *   **Likelihood:** Medium-High (same as parent node).
    *   **Impact:** High (same as parent node).
    *   **Effort:** Low-Medium (same as parent node).
    *   **Skill Level:** Medium (same as parent node).
    *   **Detection Difficulty:** Medium (same as parent node).

Attack Tree Path: [[4. CSS Injection]] (Critical Node)

  • [[4. CSS Injection]] (Critical Node): This is the primary attack vector enabled by the input validation issues.

    • Description: The attacker injects malicious CSS code into the application, typically by exploiting vulnerabilities in how user input is handled.
    • Likelihood: Medium-High (directly tied to the likelihood of input validation issues).
    • Impact: High. CSS injection can lead to:
      • Defacement: Altering the appearance of the website.
      • Data Exfiltration: Stealing sensitive information using CSS selectors and properties.
      • Phishing: Creating fake login forms or overlays.
      • Cross-Site Scripting (XSS) - in older browsers: Some older browsers had vulnerabilities that allowed CSS to execute JavaScript, effectively turning CSS injection into XSS. This is less common now, but still a consideration for legacy support.
      • Denial of Service (DoS): Crafting CSS that causes browser crashes or performance issues.
    • Effort: Low-Medium.
    • Skill Level: Medium.
    • Detection Difficulty: Medium.

Attack Tree Path: 4a. Injecting Malicious CSS via Mixins (Critical Node)

*   **4a. Injecting Malicious CSS via Mixins (Critical Node):** This is the specific method of CSS injection leveraging Bourbon.

    *   **Description:** The attacker exploits the lack of input validation in Bourbon mixins to inject their malicious CSS. This is the most direct and likely path.
    *   **Likelihood:** Medium-High (same as parent node).
    *   **Impact:** High (same as parent node).
    *   **Effort:** Low-Medium (same as parent node).
    *   **Skill Level:** Medium (same as parent node).
    *   **Detection Difficulty:** Medium (same as parent node).