attack-tree.md

Attack Tree Analysis for comfyanonymous/comfyui

Objective: Gain Unauthorized Control over ComfyUI Backend

Attack Tree Visualization

Goal: Gain Unauthorized Control over ComfyUI Backend ├── 1. Exploit Custom Node Vulnerabilities │ ├── 1.1 Code Injection in Custom Node Logic │ │ ├── 1.1.1 Unsanitized Input in Node Parameters (e.g., filename, text fields) [CRITICAL] [HIGH RISK] │ │ ├── 1.1.2 Vulnerable Dependencies within Custom Node [HIGH RISK] │ ├── 1.2 Path Traversal in Custom Node File Access │ │ ├── 1.2.1 Reading Arbitrary Files via Node Input [HIGH RISK] │ │ ├── 1.2.2 Writing to Arbitrary Files via Node Output [HIGH RISK] ├── 2. Exploit Core ComfyUI Vulnerabilities │ ├── 2.2 Workflow Execution Vulnerabilities │ │ ├── 2.2.1 Arbitrary Workflow Execution via Malicious Workflow JSON [HIGH RISK] │ ├── 2.3 Dependency Vulnerabilities in ComfyUI Itself │ │ ├── 2.3.1 Vulnerable Python Packages [HIGH RISK] │ ├── 2.5 Configuration Vulnerabilities │ ├── 2.5.1 Default or Weak Credentials [CRITICAL] ├── 3. Supply Chain Attacks ├── 3.1 Compromised Custom Node Repository ├── 3.1.1 Malicious Node Published to a Public Repository [HIGH RISK]

Attack Tree Path: 1.1.1 Unsanitized Input in Node Parameters (CRITICAL) (HIGH RISK)

• Description: Custom nodes often accept user-provided input through parameters (e.g., text fields, filenames, URLs). If this input is not properly validated and sanitized, an attacker can inject malicious code that will be executed by the ComfyUI backend. This is a classic code injection vulnerability.
• Likelihood: High. This is a common vulnerability in custom-developed code.
• Impact: Very High (RCE). Successful exploitation allows the attacker to execute arbitrary code on the server, leading to complete system compromise.
• Effort: Low. Finding and exploiting unsanitized input is often straightforward.
• Skill Level: Intermediate. Requires understanding of code injection techniques.
• Detection Difficulty: Medium (if input/output is logged), Hard (if not). Requires careful monitoring of logs or dynamic analysis of the application.
• Mitigation:
  • Strict Input Validation: Use whitelisting to allow only specific, expected input patterns. Reject any input that doesn't match the whitelist.
  • Input Sanitization: Escape or encode any special characters that could be interpreted as code.
  • Parameterization: Use parameterized queries or commands to prevent input from being treated as code.
  • Code Review: Thoroughly review custom node code for proper input handling.

Attack Tree Path: 1.1.2 Vulnerable Dependencies within Custom Node (HIGH RISK)

• Description: Custom nodes may rely on third-party libraries or packages. If these dependencies have known vulnerabilities, an attacker can exploit them to compromise the ComfyUI backend.
• Likelihood: Medium. Depends on the specific dependencies used and how frequently they are updated.
• Impact: High (RCE, Data Breach). The impact depends on the specific vulnerability, but often leads to RCE or data theft.
• Effort: Medium. Requires finding a suitable vulnerable dependency and crafting an exploit.
• Skill Level: Intermediate. Requires knowledge of vulnerability research and exploitation.
• Detection Difficulty: Hard. Requires vulnerability scanning and monitoring of dependencies.
• Mitigation:
  • Dependency Analysis: Regularly scan custom node dependencies for known vulnerabilities using tools like pip list --outdated, npm audit, or dedicated Software Composition Analysis (SCA) tools.
  • Dependency Updates: Keep dependencies up-to-date to patch known vulnerabilities.
  • Vulnerability Monitoring: Subscribe to security advisories for the dependencies used.

Attack Tree Path: 1.2.1 Reading Arbitrary Files via Node Input (HIGH RISK)

• Description: If a custom node allows reading files based on user-provided input (e.g., a filename), an attacker can use path traversal techniques (e.g., ../../etc/passwd) to read arbitrary files on the server.
• Likelihood: Medium. Depends on how file paths are handled in custom nodes.
• Impact: High (Information Disclosure, Potential RCE). Can expose sensitive data (configuration files, credentials) and potentially lead to RCE if the attacker can read executable files.
• Effort: Low. Path traversal attacks are relatively simple to execute.
• Skill Level: Intermediate. Requires understanding of file system structures and path traversal techniques.
• Detection Difficulty: Medium (if file access is logged), Hard (if not). Requires monitoring file access logs or using a Web Application Firewall (WAF).
• Mitigation:
  • Strict File Path Validation: Validate and sanitize file paths provided to custom nodes. Use a whitelist of allowed directories and file extensions.
  • Avoid User Input in Paths: Do not use user-supplied input directly in file paths. Instead, use a predefined base directory and map user input to a safe filename.
  • Sandboxing: Run custom nodes in a sandboxed environment with limited file system access.

Attack Tree Path: 1.2.2 Writing to Arbitrary Files via Node Output (HIGH RISK)

• Description: Similar to 1.2.1, but allows an attacker to write to arbitrary files on the server. This can be used to overwrite critical system files, inject malicious code, or create web shells.
• Likelihood: Medium.
• Impact: High (RCE, System Compromise).
• Effort: Low.
• Skill Level: Intermediate.
• Detection Difficulty: Medium (if file access is logged), Hard (if not).
• Mitigation: Similar to 1.2.1, but focused on output file paths. Ensure output is written to designated, sandboxed directories.

Attack Tree Path: 2.2.1 Arbitrary Workflow Execution via Malicious Workflow JSON (HIGH RISK)

• Description: ComfyUI workflows are defined using JSON. If an attacker can submit a malicious JSON workflow, they can potentially execute arbitrary code or perform unauthorized actions.
• Likelihood: Medium. Depends on how workflows are loaded and validated.
• Impact: Very High (RCE). Successful exploitation allows the attacker to execute arbitrary code within the context of the workflow execution.
• Effort: Medium. Requires crafting a malicious JSON workflow that bypasses any existing validation.
• Skill Level: Advanced. Requires a deep understanding of ComfyUI's workflow execution mechanism.
• Detection Difficulty: Hard. Requires robust input validation and anomaly detection.
• Mitigation:
  • JSON Schema Validation: Use a JSON schema validator to ensure the workflow JSON conforms to a predefined schema.
  • Input Sanitization: Sanitize the workflow JSON to remove any potentially malicious code or commands.
  • Safe Mode: Implement a "safe mode" that disables potentially dangerous nodes or features.
  • Code Review: Thoroughly review the code that handles workflow loading and execution.

Attack Tree Path: 2.3.1 Vulnerable Python Packages (HIGH RISK)

• Description: ComfyUI itself, and its core functionality, relies on Python packages. If these packages have known vulnerabilities, an attacker can exploit them.
• Likelihood: Medium.
• Impact: High (RCE, Data Breach).
• Effort: Medium.
• Skill Level: Intermediate.
• Detection Difficulty: Hard.
• Mitigation:
  • Regular Updates: Keep ComfyUI and all its Python dependencies up-to-date.
  • Vulnerability Scanning: Use tools like safety or pip-audit to scan for known vulnerabilities.

Attack Tree Path: 2.5.1 Default or Weak Credentials (CRITICAL)

• Description: If ComfyUI or any of its components use default credentials (e.g., "admin/admin"), an attacker can easily gain access.
• Likelihood: Medium (if users don't change defaults). Unfortunately, many users fail to change default credentials.
• Impact: Very High (System Compromise). Allows the attacker to gain full administrative access.
• Effort: Very Low. Requires simply trying known default credentials.
• Skill Level: Novice. No specialized skills are required.
• Detection Difficulty: Very Easy (if defaults are known). Can be detected by simply checking for the use of default credentials.
• Mitigation:
  • Change Default Credentials: Immediately change all default credentials upon installation.
  • Enforce Strong Passwords: Implement a strong password policy that requires complex passwords.
  • Multi-Factor Authentication (MFA): Implement MFA for all administrative accounts.

Attack Tree Path: 3.1.1 Malicious Node Published to a Public Repository (HIGH RISK)

• Description: An attacker could create a malicious custom node and publish it to a public repository (e.g., a GitHub repository or a community forum). If users install this node, it could compromise their ComfyUI installation.
• Likelihood: Low. Requires significant effort to create and distribute a malicious node convincingly.
• Impact: Very High (RCE, Data Breach). The malicious node could contain any of the vulnerabilities described above.
• Effort: High (to compromise a repository or gain user trust).
• Skill Level: Advanced. Requires both coding and social engineering skills.
• Detection Difficulty: Very Hard. Requires careful code review and reputation checks.
• Mitigation:
  • Vet Custom Nodes: Carefully evaluate custom nodes before installing them. Prefer nodes from trusted sources.
  • Code Review: If possible, review the source code of custom nodes before installing them.
  • Reputation Checks: Check the reputation of the node developer and the repository.
  • Internal Repository: Consider maintaining an internal, curated repository of approved custom nodes.
  • Code Signing: Implement code signing for custom nodes to verify their authenticity and integrity.