Skip to content

Latest commit

 

History

History
87 lines (72 loc) · 6.31 KB

attack-tree.md

File metadata and controls

87 lines (72 loc) · 6.31 KB

Attack Tree Analysis for thoughtbot/paperclip

Objective: To gain unauthorized access to sensitive data or execute arbitrary code on the server by exploiting vulnerabilities in the paperclip gem's file handling and processing.

Attack Tree Visualization

                                      Compromise Application via Paperclip
                                                  |
                                                  |
                                        **2. Arbitrary Code Execution** [HIGH RISK]
                                                  |
                                        -------------------------
                                        |                       |
                                     **2.1 Command Injection**   2.2 File Overwrite (Included for context, but less critical)
                                     **via Vulnerable**          via Malicious
                                     **Processors** [HIGH RISK]  Filename/Content
                                        |||
                                  ===============
                                  |             |
                               **2.1.1**       2.1.2
                               **ImageMagick**   FFmpeg
                               **Shell**         Shell
                               **Injection**     Injection
                               [HIGH RISK]

Attack Tree Path: 2. Arbitrary Code Execution [HIGH RISK]

  • Description: This is the overarching goal of the high-risk attack path. Achieving arbitrary code execution means the attacker can run any command they want on the server, effectively taking full control.
  • Likelihood: Low to Medium
  • Impact: Very High
  • Effort: Medium to High
  • Skill Level: Intermediate to Expert
  • Detection Difficulty: Hard to Very Hard

Attack Tree Path: 2.1 Command Injection via Vulnerable Processors [HIGH RISK]

  • Description: Paperclip relies on external processors (like ImageMagick and FFmpeg) to handle file transformations. These processors can be vulnerable to command injection if the input passed to them is not properly sanitized. An attacker crafts a malicious file that, when processed, executes arbitrary commands. This is the primary high-risk vector.
  • Likelihood: Low to Medium
  • Impact: Very High
  • Effort: Medium to High
  • Skill Level: Intermediate to Expert
  • Detection Difficulty: Hard to Very Hard
*   **Mitigation:**
    *   **Keep Processors Updated:** The most crucial step. Ensure ImageMagick, FFmpeg, and any other processors are running the latest patched versions.
    *   **Input Sanitization:** Rigorously sanitize *any* data passed to external processors.  Do not trust user-supplied filenames or content.  Use Paperclip's built-in sanitization, but understand its limitations and supplement it with additional checks.
    *   **Least Privilege:** Run the processors with the lowest possible privileges.  Don't run them as root.
    *   **Resource Limits:** Use `cgroups` (Linux) or `ulimit` to restrict the resources (CPU, memory) that processors can consume.
    *   **Policy Files (ImageMagick):** Configure ImageMagick with a strict `policy.xml` file to disable unnecessary coders and limit its capabilities.
    *   **Alternative Libraries:** Consider using alternative, potentially less vulnerable, libraries for image and video processing (e.g., `mini_magick` with `vips` instead of ImageMagick).

Attack Tree Path: 2.1.1 ImageMagick Shell Injection [HIGH RISK]

  • Description: ImageMagick has a history of security vulnerabilities, including shell injection flaws. An attacker uploads a specially crafted image file that exploits a known (or zero-day) ImageMagick vulnerability to execute shell commands.
  • Likelihood: Low to Medium
  • Impact: Very High
  • Effort: Medium to High
  • Skill Level: Intermediate to Expert
  • Detection Difficulty: Hard to Very Hard
  • Specific Mitigations (beyond 2.1): * Policy File (Crucial): A well-configured policy.xml is essential for mitigating ImageMagick vulnerabilities. Disable coders you don't need (e.g., MSL, MVG, potentially HTTPS if you don't process remote images). Restrict resource usage. * Disable Delegates: If you don't need ImageMagick to delegate processing to other tools (e.g., Ghostscript), disable delegates. * Monitor for Known Exploits: Stay informed about newly discovered ImageMagick vulnerabilities and apply patches immediately.

Attack Tree Path: 2.1.2 FFmpeg Shell Injection

  • Description: Similar to ImageMagick, FFmpeg can be vulnerable to shell injection if user-supplied data is not properly sanitized. An attacker could upload a malicious video file designed to exploit an FFmpeg vulnerability.
  • Likelihood: Low to Medium
  • Impact: Very High
  • Effort: Medium to High
  • Skill Level: Intermediate to Expert
  • Detection Difficulty: Hard to Very Hard
  • Specific Mitigations (beyond 2.1): * Input Validation: Be extremely cautious about any user-supplied parameters passed to FFmpeg. Validate and sanitize thoroughly. * Limited Functionality: If you only need a small subset of FFmpeg's features (e.g., thumbnail generation), consider using a more restricted wrapper or library.

Attack Tree Path: 2.2 File Overwrite via Malicious Filename/Content (Included for context, but less critical)

  • Description: Although less likely and requiring more specific conditions than command injection, file overwrite is still a potential threat. An attacker could try to upload a file with a malicious filename (path traversal) or content to overwrite existing files.
  • Likelihood: Low
  • Impact: High to Very High
  • Effort: Low to Medium
  • Skill Level: Intermediate
  • Detection Difficulty: Medium to Hard