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attack-surface.md

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Attack Surface Analysis for owncloud/core

Attack Surface: Unauthenticated File Upload leading to Remote Code Execution

  • Description: Vulnerabilities in ownCloud Core's file upload functionality allowing unauthenticated users to upload files, combined with insufficient file type validation or server-side processing flaws within core or its extensions, can lead to remote code execution.
  • How Core Contributes: ownCloud Core itself provides the core file upload mechanism and defines how files are handled within the system. Vulnerabilities in the core upload endpoints, file handling logic, or default configurations directly contribute to this attack surface. Extensions interacting with the core upload process can also introduce vulnerabilities, but the core is the initial entry point.
  • Example: An attacker exploits a vulnerability in ownCloud Core's file upload endpoint to upload a malicious PHP script. Due to insufficient validation in the core file handling routines, this script is placed in a publicly accessible directory and executed by the web server, granting the attacker control over the server.
  • Impact: Critical. Full compromise of the ownCloud server, data breach, data manipulation, denial of service.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Developers (ownCloud Core & Extensions):
      • Implement strict server-side file type validation within the core upload processing logic, using allowlists and robust checks.
      • Sanitize filenames within the core to prevent path traversal and other injection attacks during file upload and storage.
      • Secure or disable server-side file processing within core if not essential. If required, use sandboxed environments and hardened libraries within core modules.
      • Regularly update ownCloud Core and all core dependencies to patch known vulnerabilities in file handling and upload mechanisms.
      • Implement Content Security Policy (CSP) within core to mitigate execution of uploaded scripts.
    • Users/Administrators:
      • Ensure the web server configuration, interacting with ownCloud Core, prevents script execution in upload directories (e.g., using .htaccess or web server configuration).
      • Monitor upload directories for suspicious files, especially those uploaded without authentication.
      • Keep ownCloud Core and server software up to date.

Attack Surface: SQL Injection

  • Description: Improperly sanitized user inputs in database queries within ownCloud Core can allow attackers to inject malicious SQL code, leading to data breaches, data manipulation, or even database server compromise.
  • How Core Contributes: ownCloud Core directly interacts with the database for almost all operations. Vulnerabilities in the core code that constructs SQL queries without proper parameterization or input validation when handling user requests (authentication, file access, sharing, etc.) create this critical attack surface.
  • Example: An attacker crafts a malicious username containing SQL injection code during login. If ownCloud Core's core authentication logic does not properly sanitize this input before constructing the SQL query to verify credentials, the attacker could bypass authentication, retrieve user credentials directly from the database, or even execute arbitrary SQL commands.
  • Impact: Critical. Data breach, data manipulation, potential for complete database server compromise, denial of service.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Developers (ownCloud Core):
      • Mandatory use of parameterized queries or prepared statements for all database interactions within ownCloud Core. This is the primary and most crucial defense against SQL injection in the core.
      • Implement robust input validation and sanitization within core for all user-supplied data before using it in database queries. This must be enforced throughout the core codebase.
      • Follow secure coding practices and conduct rigorous code reviews specifically focused on SQL injection vulnerabilities within ownCloud Core development.
      • Utilize a database abstraction layer or ORM within core that inherently prevents SQL injection by design.
    • Users/Administrators:
      • Ensure the database server used by ownCloud Core is properly secured and hardened.
      • Regularly update ownCloud Core to benefit from security patches addressing potential SQL injection flaws in the core.
      • Monitor database logs for suspicious activity that might indicate SQL injection attempts targeting ownCloud Core.

Attack Surface: Session Hijacking and Fixation

  • Description: Vulnerabilities in ownCloud Core's session management implementation that allow attackers to steal or fixate user session IDs, enabling them to impersonate legitimate users.
  • How Core Contributes: ownCloud Core manages user sessions directly. Weaknesses in the core session ID generation, storage, or handling mechanisms are direct vulnerabilities. The core is responsible for setting session cookies, validating sessions, and managing session lifecycle.
  • Example: * Session Hijacking: ownCloud Core, if not configured to enforce HTTPS, might transmit session cookies over insecure HTTP. An attacker intercepts a user's session cookie. They then use this cookie to access the ownCloud application as the victim user, bypassing core authentication. * Session Fixation: ownCloud Core, if vulnerable to session fixation, might allow an attacker to pre-set a session ID. The attacker then tricks a user into authenticating with this pre-set ID. After authentication through core, the attacker can use the same session ID to impersonate the user.
  • Impact: High. Account compromise, unauthorized access to data, data manipulation, actions performed as the impersonated user.
  • Risk Severity: High
  • Mitigation Strategies:
    • Developers (ownCloud Core):
      • Generate strong, unpredictable session IDs using cryptographically secure random number generators within the core session management module.
      • Enforce HTTPS for all communication within ownCloud Core by default or through mandatory configuration.
      • Set the HttpOnly and Secure flags for session cookies within core session handling to prevent client-side script access and ensure cookies are only transmitted over HTTPS.
      • Implement session timeout and inactivity timeout mechanisms within core.
      • Regenerate session IDs after successful login within core authentication processes to prevent session fixation.
      • Consider implementing anti-CSRF tokens within core to further protect session integrity.
    • Users/Administrators:
      • Mandatory configuration to enforce HTTPS for all ownCloud Core access.
      • Educate users to always access ownCloud over HTTPS.
      • Ensure proper web server configuration to support and enforce HTTPS for ownCloud Core.

Attack Surface: Insecure Direct Object Reference (IDOR)

  • Description: Vulnerabilities within ownCloud Core where the application exposes direct references to internal implementation objects (file IDs, share IDs, etc.) without proper authorization checks within the core access control logic. Attackers can manipulate these references to access unauthorized data managed by core.
  • How Core Contributes: ownCloud Core defines and implements the access control model for files, shares, and other resources. If the core code's authorization checks are insufficient or flawed when accessing resources based on identifiers, it directly creates IDOR vulnerabilities. The core is responsible for validating if a user is authorized to access a resource based on its ID.
  • Example: A user is able to access a file by directly manipulating a file ID in the URL, even if the file is not explicitly shared with them. This occurs because ownCloud Core's core authorization logic when handling file access requests based on IDs fails to properly verify if the user has the necessary permissions beyond just checking the ID's existence.
  • Impact: High. Unauthorized access to sensitive files and data managed by core, data breach, potential privilege escalation within the ownCloud system.
  • Risk Severity: High
  • Mitigation Strategies:
    • Developers (ownCloud Core):
      • Implement robust authorization checks within core at every access point to resources. Ensure that core verifies users are explicitly authorized to access resources based on their IDs before granting access. Authorization must be enforced at the core level.
      • Avoid exposing direct object references (e.g., database IDs) in URLs or client-side code generated by core. Use indirect references or access control mechanisms within core APIs and interfaces.
      • Implement and enforce access control lists (ACLs) or role-based access control (RBAC) within ownCloud Core to manage permissions effectively and consistently.
    • Users/Administrators:
      • Regularly review sharing permissions and access controls within ownCloud, ensuring they are configured as intended to limit exposure based on core's access management.
      • Report any unexpected access behavior or potential IDOR vulnerabilities to the ownCloud Core developers or administrators.