threat-modeling.md

Threat Model Analysis for yiisoft/yii2

Threat: Yii2 Core Bug - Remote Code Execution (RCE)

• Description: An attacker exploits an undiscovered vulnerability in Yii2 core code. By crafting a malicious request, they can trigger the bug and execute arbitrary code on the server. This could involve injecting code through input parameters or manipulating request headers to exploit weaknesses in request handling or routing logic within Yii2.
• Impact: Full compromise of the web server and application. The attacker gains complete control, can steal data, modify application logic, install malware, or use the server for further attacks.
• Yii2 Component Affected: Yii2 Core Framework (potentially Request, Router, or other core components)
• Risk Severity: Critical
• Mitigation Strategies:
  • Keep Yii2 framework updated to the latest stable version.
  • Monitor Yii2 security advisories and apply security patches immediately.
  • Implement a Web Application Firewall (WAF) to detect and block malicious requests targeting known or zero-day vulnerabilities.
  • Conduct regular security code reviews and penetration testing to identify potential vulnerabilities proactively.

Threat: Deserialization Vulnerability - Object Injection

• Description: An attacker exploits Yii2's deserialization processes, particularly if user-controlled data is involved. By injecting malicious serialized objects, they can achieve Remote Code Execution when these objects are deserialized by the application. This could target Yii2 components like Session or Cache that might use serialization internally or when developers use serialization with user inputs.
• Impact: Remote Code Execution (RCE), leading to full server compromise and data breaches.
• Yii2 Component Affected: Yii2 Core Framework (potentially Session, Cache, or components using serialization)
• Risk Severity: Critical
• Mitigation Strategies:
  • Avoid deserializing user-controlled data whenever possible.
  • If deserialization is absolutely necessary, use secure and well-vetted deserialization methods. Sanitize and strictly validate input before deserialization.
  • Regularly audit code for potential deserialization vulnerabilities.
  • Consider using safer data formats like JSON instead of PHP's native serialization where feasible.

Threat: Insecure Cookie Configuration - Session Hijacking

• Description: An attacker intercepts or steals session cookies due to misconfigured Yii2 cookie settings. Missing httpOnly or secure flags, or a weak cookieValidationKey can make session cookies vulnerable to theft. With a stolen cookie, an attacker can impersonate a legitimate user, gaining unauthorized access to their account and application functionalities.
• Impact: Unauthorized access to user accounts, data breaches, and potential manipulation of user data or application functionality within the context of the hijacked session.
• Yii2 Component Affected: Yii2 Request/Response, Session Component
• Risk Severity: High
• Mitigation Strategies:
  • Strictly configure cookie parameters in Yii2 application configuration: httpOnly: true, secure: true (for HTTPS), and sameSite: 'Strict' or 'Lax' as appropriate.
  • Use a strong, randomly generated, and unique cookieValidationKey in Yii2 configuration. Rotate this key periodically.
  • Enforce HTTPS for all application traffic to protect cookies in transit and prevent man-in-the-middle attacks.

Threat: Debug Mode Enabled in Production - Information Disclosure

• Description: An attacker accesses a production Yii2 application with debug mode enabled. Yii2's debug mode exposes detailed error messages, stack traces, and debugging tools. This reveals sensitive information about the application's internal workings, configuration, and potential vulnerabilities, aiding attackers in planning further attacks.
• Impact: Information disclosure of sensitive application details, potentially including database credentials, application paths, code structure, and vulnerabilities. This information significantly lowers the barrier for further, more severe attacks.
• Yii2 Component Affected: Yii Debug Module
• Risk Severity: High
• Mitigation Strategies:
  • Absolutely ensure debug mode is disabled in production environments. Set YII_DEBUG environment variable or debug configuration parameter to false in production.
  • Implement robust environment-specific configuration management to prevent accidental debug mode activation in production deployments.
  • Regularly audit production configurations and deployments to verify debug mode is disabled and no debugging tools are exposed.

Threat: Insecure File Upload Handling - Arbitrary File Upload & RCE

• Description: An attacker exploits weaknesses in the application's file upload functionality, often built using Yii2's file handling features. By bypassing validation, they upload a malicious executable file (e.g., a PHP script). If the application fails to properly secure uploaded files (e.g., storing them within the webroot and allowing direct access), the attacker can execute the malicious file, achieving Remote Code Execution.
• Impact: Remote Code Execution (RCE), full server compromise, data breaches, website defacement, and potential for persistent backdoors.
• Yii2 Component Affected: Yii2 UploadedFile, FileHelper
• Risk Severity: Critical
• Mitigation Strategies:
  • Implement robust file validation using Yii2's features, strictly limiting allowed file types and sizes.
  • Validate file types based on file content (magic numbers) and not solely on file extensions.
  • Store uploaded files outside of the webroot in a dedicated, protected storage location with restricted access.
  • Generate unique and unpredictable filenames for uploaded files to prevent direct access attempts.
  • Implement strict access controls to prevent direct execution of uploaded files by the web server. Consider using a separate domain or subdomain for serving user-uploaded content with restricted execution permissions.

Threat: Misconfigured Access Control (RBAC/ACL) - Privilege Escalation

• Description: An attacker exploits misconfigurations or flaws in the application's Role-Based Access Control (RBAC) or Access Control List (ACL) implementation, often using Yii2's Auth Manager. Incorrectly defined or overly permissive access rules can allow an attacker with low privileges to gain access to functionalities or data intended for higher-privileged users or administrators, effectively escalating their privileges within the application.
• Impact: Privilege escalation, unauthorized access to sensitive data and functionalities, potential data breaches, and disruption of application operations due to unauthorized actions.
• Yii2 Component Affected: Yii2 Auth Manager (RBAC), AccessControl Filter
• Risk Severity: High
• Mitigation Strategies:
  • Design and implement RBAC or ACL rules based on the principle of least privilege. Grant only the necessary permissions required for each role or user.
  • Thoroughly test access control configurations to ensure they function as intended and prevent unintended access paths.
  • Regularly review and audit access control rules, user roles, and permissions to identify and rectify any misconfigurations or overly permissive settings.
  • Utilize Yii2's built-in RBAC features correctly and avoid creating custom, potentially flawed, access control implementations if possible.

Threat: Improper Use of Security Components - Weak Password Hashing

• Description: Developers improperly use Yii2's security components, particularly the Security component for password hashing. Using outdated or weak hashing algorithms (like MD5 or SHA1) instead of strong algorithms (bcrypt or Argon2), or incorrect parameter usage, results in weak password hashes. These weak hashes are significantly easier for attackers to crack through brute-force or dictionary attacks if the password database is compromised.
• Impact: Password database compromise, leading to unauthorized access to user accounts, widespread data breaches, and potential identity theft.
• Yii2 Component Affected: Yii2 Security Component
• Risk Severity: High
• Mitigation Strategies:
  • Use Yii2's Security component correctly and exclusively for password hashing.
  • Always utilize strong and modern hashing algorithms like bcrypt or Argon2, which are well-supported by Yii2.
  • Strictly adhere to Yii2 documentation and security best practices for password hashing.
  • Regularly review and update password hashing implementation to ensure it remains secure against evolving password cracking techniques and computational advancements. Consider using password salting correctly.

Threat: Vulnerable Composer Dependencies - Supply Chain Attack

• Description: An attacker exploits known vulnerabilities in third-party libraries used by the Yii2 application, managed by Composer. These vulnerabilities can exist in Yii2 itself or in any of its dependencies. By targeting these vulnerabilities, attackers can compromise the application or server. This represents a supply chain attack, as the vulnerability originates from an external dependency.
• Impact: Impact varies depending on the vulnerability, ranging from Denial of Service (DoS) to Remote Code Execution (RCE), and data breaches. Vulnerabilities in widely used dependencies can have a broad and severe impact.
• Yii2 Component Affected: Composer, Third-party Libraries
• Risk Severity: Varies (can be Critical to High depending on the vulnerability)
• Mitigation Strategies:
  • Regularly audit and update Composer dependencies using composer audit or dedicated automated dependency scanning tools.
  • Keep all dependencies up-to-date with the latest security patches and stable versions.
  • Proactively monitor security advisories for Yii2 and all its dependencies.
  • Implement a Software Composition Analysis (SCA) tool in the development pipeline to continuously monitor and alert on vulnerable dependencies.

Threat: Vulnerable or Malicious Yii2 Extension - Extension Compromise

• Description: An attacker exploits vulnerabilities within a Yii2 extension used by the application, or the extension itself is intentionally malicious (backdoored). Yii2 extensions have extensive access to the application and server environment. Vulnerabilities or malicious code within an extension can be leveraged to fully compromise the application.
• Impact: Wide range of severe impacts, including Remote Code Execution (RCE), data breaches, installation of backdoors for persistent access, website defacement, and denial of service. The impact is highly dependent on the extension's functionality and the nature of the vulnerability or malicious code.
• Yii2 Component Affected: Yii2 Extension System, specific vulnerable/malicious extension
• Risk Severity: Varies (can be Critical to High depending on the extension and vulnerability)
• Mitigation Strategies:
  • Exercise extreme caution when selecting and using Yii2 extensions. Only use extensions from highly trusted and reputable sources (official Yii extensions, well-known developers/organizations with a strong security track record).
  • Carefully review extension code before installation, especially for extensions from less established sources. Pay close attention to permissions requested and any potentially suspicious code patterns.
  • Keep all installed extensions updated to their latest versions to patch known vulnerabilities.
  • Regularly audit installed extensions for known vulnerabilities using security scanning tools designed for Yii2 or PHP applications.
  • Implement a Content Security Policy (CSP) to limit the capabilities of extensions and mitigate potential damage in case of compromise. Consider using Subresource Integrity (SRI) for external extension assets.