attack-surface.md

Attack Surface Analysis for usememos/memos

Attack Surface: Cross-Site Scripting (XSS) via Note Content (Stored XSS)

• Description: Malicious JavaScript code injected into memo content is stored and executed in the browsers of other users viewing the memo. This is due to insufficient sanitization of user-provided memo content.
• Memos Contribution: Memos' core functionality of creating and displaying notes, especially with rich text formatting like Markdown, makes it vulnerable if input sanitization is lacking.
• Example: A user creates a memo with Markdown including `<script>/* malicious JS */</script>`. When another user views this memo, the script executes, potentially stealing session cookies or redirecting to malicious sites.
• Impact: High - Account takeover of users viewing the malicious memo, data theft, defacement within the application for other users.
• Risk Severity: High
• Mitigation Strategies:
  • Developers:
    • Robust Input Sanitization and Output Encoding: Implement strict sanitization and output encoding for all user-provided memo content before rendering. Utilize a security-focused Markdown parser and HTML sanitizer library. Ensure proper escaping of HTML entities and JavaScript-sensitive characters.
    • Content Security Policy (CSP): Implement a strict Content Security Policy to limit script execution sources, mitigating the impact of XSS.

Attack Surface: Unrestricted File Uploads (If Attachment Feature is Implemented)

• Description: If Memos allows file attachments to memos, lack of restrictions on file types or content can lead to uploading malicious files, potentially compromising the server or other users.
• Memos Contribution: A file attachment feature in Memos, if implemented without proper security measures, directly introduces this attack surface.
• Example: An attacker uploads a malicious PHP script disguised as an image. If the server is misconfigured, this script could be executed, granting the attacker remote code execution.
• Impact: Critical - Remote code execution on the server, full server compromise, potential for data breaches, malware distribution to users downloading attachments.
• Risk Severity: Critical
• Mitigation Strategies:
  • Developers:
    • Strict File Type Whitelisting: Only allow explicitly permitted and safe file types for upload based on application needs.
    • File Size Limits: Enforce reasonable file size limits to prevent denial-of-service.
    • Input Sanitization and Validation: Sanitize and validate file names to prevent path traversal and injection attacks.
    • Secure File Storage: Store uploaded files outside the webroot with restricted access.
    • Antivirus/Malware Scanning: Integrate malware scanning for uploaded files to prevent storage of malicious content.

Attack Surface: Password Reset Vulnerabilities

• Description: Weaknesses in the password reset process can allow attackers to reset passwords of other users and gain unauthorized account access.
• Memos Contribution: Memos' user account management, including password reset functionality, is a direct contributor if the reset process is not securely implemented.
• Example: The password reset mechanism uses predictable reset tokens. An attacker could guess a token for another user, use it to reset their password, and take over their account.
• Impact: High - Account takeover, unauthorized access to user memos and potentially sensitive information.
• Risk Severity: High
• Mitigation Strategies:
  • Developers:
    • Secure Token Generation: Use cryptographically strong, unpredictable, and unique tokens for password reset links.
    • Token Expiration: Implement short expiration times for reset tokens.
    • Account Verification: Ensure password reset requires verification via email to the registered account.
    • Rate Limiting: Implement rate limiting on password reset requests to prevent brute-force token guessing.