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Mitigation Strategies Analysis for mattermost/mattermost-server

Mitigation Strategy: Strict System Console Permission Control

1. Mitigation Strategy: Strict System Console Permission Control

  • Description:

    1. Identify Core Admins: Determine the minimum number of users needing full System Console access.
    2. Create Custom Roles: Within the Mattermost System Console ("Permissions" -> "Roles"), create custom roles with granular permissions. Examples:
      • "Integration Manager": Manage integrations, but not system settings or users.
      • "Team Administrator": Manage a specific team, not others or system settings.
      • "Channel Moderator": Moderate channels, not create them or manage users.
    3. Assign Roles: Assign users to these custom roles instead of full System Administrator. Regularly review assignments.
    4. Revoke Unnecessary Permissions: Review existing System Administrators' permissions; revoke any not strictly needed.
    5. Document: Maintain clear documentation of permissions and assignments.

  • Threats Mitigated:

    • Unauthorized System Configuration Changes (Severity: High): Prevents unauthorized users from altering critical settings, leading to data exposure or disruption.
    • Malicious Plugin/Integration Installation (Severity: High): Limits compromised accounts or malicious insiders from installing harmful plugins/integrations.
    • Privilege Escalation (Severity: High): Reduces the chance of attackers escalating from lower-level accounts to System Administrator.
    • Accidental Misconfiguration (Severity: Medium): Reduces unintentional changes by users lacking full understanding.

  • Impact:

    • Unauthorized System Configuration Changes: Risk significantly reduced (80-90%).
    • Malicious Plugin/Integration Installation: Risk significantly reduced (70-80%).
    • Privilege Escalation: Risk significantly reduced (70-80%).
    • Accidental Misconfiguration: Risk moderately reduced (50-60%).

  • Currently Implemented:

    • Partially. Basic System Administrator role exists, but custom roles are underutilized. Some users have excessive permissions.

  • Missing Implementation:

    • Creation and use of granular custom roles.
    • Regular review/audit of System Console permissions.
    • Formal documentation of assignments.

Mitigation Strategy: Enforce Multi-Factor Authentication (MFA)

2. Mitigation Strategy: Enforce Multi-Factor Authentication (MFA)

  • Description:

    1. Enable MFA: In the System Console, go to "Authentication" -> "MFA".
    2. Choose Method: Select a supported MFA method (e.g., TOTP apps like Google Authenticator).
    3. Enforce MFA: Set "Enforce Multi-factor Authentication" to "true". This makes MFA mandatory for all users.
    4. User Education: Provide instructions on setting up and using MFA.
    5. Monitor Usage: Regularly check that users have MFA enabled and are using it.

  • Threats Mitigated:

    • Account Takeover via Password Compromise (Severity: High): Reduces risk even if passwords are obtained.
    • Brute-Force Attacks (Severity: Medium): Makes brute-force much harder; attackers need both password and MFA token.
    • Credential Stuffing (Severity: High): Protects against using stolen credentials from other breaches.

  • Impact:

    • Account Takeover via Password Compromise: Risk drastically reduced (95-99%).
    • Brute-Force Attacks: Risk significantly reduced (90-95%).
    • Credential Stuffing: Risk drastically reduced (95-99%).

  • Currently Implemented:

    • MFA is enabled, but not enforced. Some users have it, others don't.

  • Missing Implementation:

    • Mandatory MFA enforcement for all accounts.
    • Comprehensive user education/onboarding.
    • Regular monitoring of MFA usage.

Mitigation Strategy: Restrict File Uploads

3. Mitigation Strategy: Restrict File Uploads

  • Description:

    1. System Console Settings: Go to "Files" -> "Storage" in the System Console.
    2. Maximum File Size: Set a reasonable "Maximum File Size" (e.g., 20MB, 50MB), based on user needs.
    3. Allowed File Types: Crucially, use a whitelist. Only list explicitly allowed extensions (e.g., .pdf, .docx, .xlsx, .pptx, .jpg, .jpeg, .png, .gif, .txt). Do not use a blacklist.
    4. Antivirus Integration (If Available): If using a supported antivirus, configure the integration to scan uploads.
    5. Regular Review: Periodically review settings.

  • Threats Mitigated:

    • Malware Upload (Severity: High): Prevents uploading malicious files (executables, scripts) that could compromise the server or users.
    • Denial-of-Service (DoS) via Large Files (Severity: Medium): Limits file sizes, preventing server overload.
    • Storage Exhaustion (Severity: Medium): Prevents running out of storage due to large uploads.
    • Data Exfiltration (Severity: Medium): Restricting types can hinder exfiltration of certain data (though not a primary defense).

  • Impact:

    • Malware Upload: Risk significantly reduced (80-90%, depending on whitelist and antivirus).
    • Denial-of-Service (DoS) via Large Files: Risk significantly reduced (70-80%).
    • Storage Exhaustion: Risk moderately reduced (50-60%).
    • Data Exfiltration: Risk slightly reduced (20-30%).

  • Currently Implemented:

    • A maximum file size limit exists, but is high (100MB).
    • A blacklist of file types is used (less secure).
    • No antivirus integration.

  • Missing Implementation:

    • Strict whitelist of allowed file types.
    • Reduction of maximum file size.
    • Antivirus integration.

Mitigation Strategy: Plugin Management and Approval Process

4. Mitigation Strategy: Plugin Management and Approval Process

  • Description:

    1. Establish a Plugin Repository: Curate a list of approved plugins (Mattermost Marketplace and internally vetted).
    2. Security Review Process: Before approval, review:
      • Source Code Review (if available): Check for vulnerabilities.
      • Permission Analysis: Review requested permissions.
      • Reputation Check: Research developer and community reputation.
      • Testing: Test in a staging environment before production.
    3. Plugin Whitelisting (Optional but Recommended): Configure Mattermost to only allow approved plugins. Strongest protection. This is done via the PluginSettings -> AllowedPaths in the config.json file, or via the MM_PLUGINSETTINGS_ALLOWEDPATHS environment variable. It's a direct Mattermost server configuration.
    4. Regular Updates: Update plugins to patch vulnerabilities.
    5. Disable Unused Plugins: Remove unneeded plugins to reduce attack surface. This is done directly within the Mattermost System Console.
    6. Documentation: Document the process and list approved/installed plugins.

  • Threats Mitigated:

    • Malicious Plugin Installation (Severity: High): Prevents installing malicious plugins.
    • Vulnerable Plugin Exploitation (Severity: High): Reduces risk from outdated/poorly written plugins.
    • Data Breaches via Plugins (Severity: High): Limits plugin access to sensitive data.
    • System Instability (Severity: Medium): Prevents poorly written plugins from causing issues.

  • Impact:

    • Malicious Plugin Installation: Risk significantly reduced (80-90% with whitelist).
    • Vulnerable Plugin Exploitation: Risk significantly reduced (70-80% with updates).
    • Data Breaches via Plugins: Risk significantly reduced (60-70%).
    • System Instability: Risk moderately reduced (50-60%).

  • Currently Implemented:

    • No formal approval process.
    • Plugins installed from Marketplace without thorough review.
    • Updates not consistently applied.

  • Missing Implementation:

    • Formal approval process and curated list.
    • Plugin whitelisting (if feasible).
    • Regular review/update process.
    • Documentation.

Mitigation Strategy: Configure Rate Limiting (Within Mattermost)

5. Mitigation Strategy: Configure Rate Limiting (Within Mattermost)

  • Description:

    1. Access config.json: Locate and edit the config.json file for your Mattermost server. Alternatively, use environment variables.
    2. RateLimitSettings: Within the RateLimitSettings section, configure the following:
      • Enable: Set to true to enable rate limiting.
      • PerSec: The maximum number of requests per second per IP address. Start with a conservative value (e.g., 5-10) and adjust as needed.
      • MaxBurst: The maximum number of requests allowed in a burst, above the PerSec limit.
      • MemoryStoreSize: The number of requests to track in memory.
      • VaryByRemoteAddr: Set to true to rate limit based on IP address.
      • VaryByHeader: Optionally, rate limit based on specific headers (e.g., X-Forwarded-For if behind a proxy). Use with caution.
    3. Restart Mattermost: Restart the Mattermost server for the changes to take effect.
    4. Monitor and Adjust: Monitor server logs and performance to fine-tune the rate limiting settings. Too strict settings can impact legitimate users.

  • Threats Mitigated:

    • Brute-Force Attacks (Severity: Medium): Makes it much more difficult for attackers to guess passwords by repeatedly trying different combinations.
    • Denial-of-Service (DoS) Attacks (Severity: Medium): Helps prevent the server from being overwhelmed by a flood of requests.
    • API Abuse (Severity: Medium): Limits the rate at which attackers can exploit API vulnerabilities or scrape data.

  • Impact:

    • Brute-Force Attacks: Risk significantly reduced (e.g., 70-80%).
    • Denial-of-Service (DoS) Attacks: Risk moderately reduced (e.g., 30-50%). This is a partial mitigation; a dedicated WAF or DDoS protection service is still recommended for robust DoS protection.
    • API Abuse: Risk moderately reduced (e.g., 40-60%).

  • Currently Implemented:

    • Rate limiting is likely not configured or is set to very permissive defaults.

  • Missing Implementation:

    • Proper configuration of RateLimitSettings in config.json (or via environment variables).
    • Monitoring and adjustment of rate limiting settings based on observed traffic.

Mitigation Strategy: Enable Detailed Logging and Auditing

6. Mitigation Strategy: Enable Detailed Logging and Auditing

  • Description:

    1. System Console Settings: Navigate to "Environment" -> "Logging" in the System Console.
    2. Enable File Output: Set "Output logs to file" to "true".
    3. File Log Level: Set "File Log Level" to "DEBUG" for maximum detail, or "INFO" for a less verbose but still informative level. "ERROR" is generally insufficient for security auditing.
    4. Enable Console Output (Optional): You can also enable console output for real-time monitoring, but file output is crucial for long-term retention.
    5. Enable JSON Output (Recommended): Set "Enable JSON Output" to "true". This makes logs easier to parse and analyze by log management tools.
    6. Log Rotation: Configure log rotation settings (file size, number of files) to prevent logs from consuming excessive disk space. This is often handled outside of Mattermost, at the OS level, but Mattermost has some basic settings.
    7. Audit Logs: Ensure audit logging is enabled. This is usually on by default, but verify. Audit logs track important events like user logins, permission changes, and configuration changes.

  • Threats Mitigated:

    • Incident Detection (Severity: High): Detailed logs are essential for detecting suspicious activity and security incidents.
    • Forensic Analysis (Severity: High): Logs provide crucial evidence for investigating security breaches and understanding the scope of an attack.
    • Compliance (Severity: Medium): Many compliance regulations require detailed logging and auditing.
    • Troubleshooting (Severity: Low): Logs can also help diagnose and troubleshoot non-security-related issues.

  • Impact:

    • Incident Detection: Significantly improved ability to detect incidents.
    • Forensic Analysis: Enables thorough investigation of security events.
    • Compliance: Helps meet regulatory requirements.
    • Troubleshooting: Improves ability to diagnose problems.
    • Note: Logging itself doesn't prevent threats, but it's crucial for detection, response, and recovery.

  • Currently Implemented:

    • Basic logging is likely enabled, but the level of detail may be insufficient.
    • JSON output may not be enabled.
    • Log rotation may not be properly configured.

  • Missing Implementation:

    • Setting "File Log Level" to "DEBUG" or "INFO".
    • Enabling JSON output.
    • Configuring robust log rotation.
    • Regular review of logs for suspicious activity.