threat-modeling.md

Threat Model Analysis for standardnotes/app

Threat: Malicious Standard Notes Extension Injection

• Threat: Malicious Standard Notes Extension Injection

  • Description: An attacker crafts a malicious Standard Notes extension that appears legitimate. They exploit a vulnerability in our application's extension loading mechanism to install it (with or without user interaction, depending on the vulnerability). The malicious extension could steal data, modify notes, or execute arbitrary code within the context of our application. This assumes our application allows for the installation of Standard Notes extensions.
  • Impact:
    • Compromise of user's notes (confidentiality, integrity).
    • Potential execution of arbitrary code within our application, leading to a full system compromise.
    • Loss of user trust and significant reputational damage.
  • Affected Component:
    • Extension loading/management module (e.g., functions for fetching, validating, installing, and running extensions).
    • Any component that interacts with the extension's API (if the extension provides an API).
  • Risk Severity: Critical (if arbitrary code execution is possible) or High (if limited to data access/modification within the extension's sandbox).
  • Mitigation Strategies:
    • Developer:
      • Implement a very strict extension vetting process. Ideally, only allow extensions from a tightly controlled, officially sanctioned source.
      • Use strong code signing and verification. Reject any extension that fails signature checks.
      • Implement robust sandboxing. Use Web Workers or iframes with strict sandbox attributes to isolate extensions and severely limit their access to the main application context and system resources. Consider using a Content Security Policy (CSP) to further restrict extension capabilities.
      • Regularly audit the extension loading, management, and sandboxing code. This is a high-risk area.
      • Provide clear, unavoidable UI warnings to users before installing any extension, emphasizing the risks.
      • Implement a mechanism to disable or uninstall extensions remotely if a vulnerability is discovered.

Threat: Sync Token Leakage via Logging or Error Handling

• Threat: Sync Token Leakage via Logging or Error Handling

  • Description: Our application inadvertently logs the Standard Notes sync token (or other sensitive authentication credentials related to Standard Notes) to application logs, error reports, or debugging output. An attacker who gains access to these logs (through a separate vulnerability in our application, social engineering, or other means) can then impersonate the user and access their Standard Notes data via our application.
  • Impact:
    • Unauthorized access to the user's Standard Notes account and all associated notes through our application.
    • Potential for data modification or deletion.
  • Affected Component:
    • Any component that handles the sync token. This includes:
      • Logging functions.
      • Error handling routines.
      • API request/response handlers (especially if the token is included in requests).
      • Configuration management (if the token is stored insecurely).
  • Risk Severity: High
  • Mitigation Strategies:
    • Developer:
      • Implement strict redaction rules for logging. Use a logging library with built-in redaction capabilities, and configure it to never log sensitive data like sync tokens, API keys, or passwords. Use regular expressions or other pattern matching to identify and redact sensitive data.
      • Regularly review all logging configurations and code to ensure no sensitive data is being leaked. This is a continuous process.
      • Store sync tokens securely. Use the operating system's secure credential storage (e.g., Keychain on macOS, Credential Manager on Windows) or a dedicated secrets management solution. Never store tokens in plain text in configuration files or environment variables.
      • Use short-lived tokens and implement automatic token rotation.
      • Sanitize error messages and API responses to prevent token leakage.

Threat: Decrypted Note Exposure in Memory

• Threat: Decrypted Note Exposure in Memory

  • Description: Our application decrypts Standard Notes content for processing (displaying, searching, editing). If the application doesn't handle this decrypted data securely in memory, an attacker who gains access to the application's runtime environment (e.g., through a memory dump, a debugger attached to the process, or exploiting another vulnerability in our application) could read the decrypted notes.
  • Impact:
    • Compromise of user's note confidentiality.
  • Affected Component:
    • Any component that decrypts or processes note content. This includes:
      • Functions responsible for decryption.
      • Rendering components that display note content.
      • Editing components.
      • Search functionality.
      • Memory management routines.
  • Risk Severity: High
  • Mitigation Strategies:
    • Developer:
      • Minimize the time that decrypted note data exists in memory. Decrypt only when absolutely necessary and immediately clear the memory after use (e.g., using memset or equivalent, depending on the language).
      • Use secure memory management techniques. Avoid global variables or long-lived objects for decrypted data. Consider using specialized libraries for secure memory handling if available for your platform/language.
      • If possible, perform operations on encrypted data directly, avoiding decryption whenever feasible (e.g., for some types of indexing or filtering).
      • Leverage operating system memory protection mechanisms (ASLR, DEP/NX) to make exploitation more difficult.
      • Regularly review memory handling code for potential vulnerabilities.

Threat: Improper Permissions Handling for Shared Notes (If Applicable)

• Threat: Improper Permissions Handling for Shared Notes (If Applicable)

  • Description: If our application integrates with Standard Notes' sharing features (or implements its own sharing on top of Standard Notes), a vulnerability in our application's permissions handling could allow unauthorized users to access or modify shared notes. This is due to flaws in our code, not necessarily Standard Notes itself.
  • Impact:
    • Unauthorized access to or modification of shared notes.
    • Violation of user privacy and data integrity.
  • Affected Component:
    • Any component that handles note sharing in our application. This includes:
      • Functions for creating, managing, and enforcing sharing permissions.
      • Database queries or API calls that retrieve or update shared note metadata within our application's context.
  • Risk Severity: High
  • Mitigation Strategies:
    • Developer:
      • Implement robust access control mechanisms based on the principle of least privilege. Ensure users can only access notes they are explicitly authorized to access.
      • Regularly audit the permissions handling code. This is a critical area.
      • Use a well-defined and thoroughly tested permissions model.
      • Thoroughly test all sharing-related functionality, including edge cases and error conditions.
      • Ensure that permissions are correctly synchronized with the Standard Notes server (if applicable) and that our application handles any discrepancies gracefully.