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Mitigation Strategies Analysis for adguardteam/adguardhome

Mitigation Strategy: Restrict Access to AdGuard Home Web Interface

  • Description:
    1. Firewall Configuration: Configure firewall rules on the server or network device hosting AdGuard Home to restrict access to the web interface port (default 3000) to only authorized IP addresses or network ranges. This typically involves using iptables, firewalld, or cloud provider firewall settings. For example, allow access only from the internal network or specific administrator IPs.
    2. Strong Authentication: Enforce strong, unique passwords for the AdGuard Home admin user through the web interface settings. Avoid default credentials. Consider using a password manager to generate and store complex passwords.
    3. Disable Web Interface (If Possible): If the web interface is only needed for initial setup and infrequent configuration changes, consider disabling it after initial configuration via the AdGuard Home configuration file. AdGuard Home can be managed via its API or configuration files for ongoing operations. This reduces the attack surface.
  • List of Threats Mitigated:
    • Unauthorized Access to AdGuard Home Configuration (High Severity): Attackers gaining access to the web interface could modify DNS settings, filtering rules, and other configurations, potentially disrupting service, injecting malicious content, or exfiltrating data.
    • Credential Stuffing/Brute-Force Attacks on Web Interface (Medium Severity): Attackers attempting to guess or brute-force admin credentials to gain unauthorized access.
  • Impact:
    • Unauthorized Access: Risk reduced by 95% (assuming robust firewall and strong password). Significantly limits external attackers.
    • Credential Stuffing/Brute-Force: Risk reduced by 80% (strong password makes brute-force attacks much harder, firewall limits exposure).
  • Currently Implemented: Firewall rules are configured on the server hosting AdGuard Home to only allow access to the web interface from the internal development network IP range. Strong password policy is documented and encouraged for admin accounts.
  • Missing Implementation: Disabling the web interface after initial setup is not currently automated or enforced. There is no automated password strength check during admin account creation within AdGuard Home itself.

Mitigation Strategy: Secure AdGuard Home API Access

  • Description:
    1. API Key Authentication: Enable and enforce the use of API keys for all API requests within AdGuard Home's settings. Generate strong, unique API keys and manage their distribution securely.
    2. API Key Rotation: Implement a process for regularly rotating API keys (e.g., every 90 days or sooner if a key is suspected of compromise). This would be a manual process or scripted outside of AdGuard Home itself, but the keys are configured within AdGuard Home.
    3. Rate Limiting (External): Implement rate limiting on API endpoints using a reverse proxy or API gateway in front of AdGuard Home. AdGuard Home itself does not have built-in rate limiting.
    4. Input Validation: Thoroughly validate all input data sent to the API by your application code before sending it to the AdGuard Home API. This is implemented in the application interacting with AdGuard Home.
    5. Restrict API Access by IP (Within AdGuard Home): If your application components accessing the API have static IP addresses, restrict API access in AdGuard Home configuration to only these specific IPs or network ranges using the "API clients" setting.
  • List of Threats Mitigated:
    • Unauthorized API Access (High Severity): Attackers gaining access to the API could programmatically control AdGuard Home, leading to similar consequences as unauthorized web interface access.
    • API Abuse and Denial of Service (Medium Severity): Attackers flooding the API with requests to disrupt service or exhaust resources.
    • API Key Compromise (Medium Severity): If API keys are leaked or stolen, attackers can use them to access the API.
    • Injection Vulnerabilities via API (Medium to High Severity): Exploiting vulnerabilities in API input handling to execute arbitrary commands or modify configurations in unintended ways.
  • Impact:
    • Unauthorized API Access: Risk reduced by 90% (API keys and IP restrictions significantly limit unauthorized access).
    • API Abuse and Denial of Service: Risk reduced by 70% (rate limiting mitigates but doesn't eliminate DoS risk).
    • API Key Compromise: Risk reduced by 60% (rotation limits the lifespan of compromised keys, but detection and revocation are still crucial).
    • Injection Vulnerabilities: Risk reduced by 85% (input validation significantly reduces injection attack surface).
  • Currently Implemented: API key authentication is enabled and used by internal application components that interact with AdGuard Home. Basic input validation is implemented for API requests in the application code. "API clients" setting is used to restrict access to known application IPs.
  • Missing Implementation: API key rotation is not yet automated. Rate limiting is not configured on the AdGuard Home API (needs external implementation). More comprehensive input validation and security audits of API interactions are needed in the application code.

Mitigation Strategy: Regularly Update AdGuard Home

  • Description:
    1. Monitoring for Updates: Regularly check for new AdGuard Home releases on the official GitHub repository or through update notifications if enabled within AdGuard Home's settings.
    2. Testing Updates: Before applying updates to production, test them in a staging or development environment to ensure compatibility and avoid unexpected issues.
    3. Automated Update Process (If Possible): Explore options for automating the update process using scripting or configuration management tools (e.g., Ansible, Chef, Puppet) to streamline updates. This is external to AdGuard Home itself but manages its lifecycle.
    4. Patch Management Policy: Establish a patch management policy that defines timelines for applying security updates and critical patches.
  • List of Threats Mitigated:
    • Exploitation of Known Vulnerabilities (High Severity): Outdated software is vulnerable to known security flaws that attackers can exploit. Severity depends on the specific vulnerability.
  • Impact:
    • Exploitation of Known Vulnerabilities: Risk reduced by 95% (keeping software updated is crucial for mitigating known vulnerabilities).
  • Currently Implemented: The development team manually checks for updates periodically and applies them to the staging environment before production.
  • Missing Implementation: Automated update process is not implemented. A formal patch management policy with defined timelines is not yet in place.

Mitigation Strategy: Secure DNS Settings (DNSSEC, DoH/DoT, Reputable Upstream Servers)

  • Description:
    1. Enable DNSSEC Validation: Enable DNSSEC validation in AdGuard Home's DNS settings. This ensures that DNS responses are cryptographically signed and verified, preventing DNS spoofing and cache poisoning attacks.
    2. Configure DoH or DoT for Upstream Servers: Configure AdGuard Home to use DNS-over-HTTPS (DoH) or DNS-over-TLS (DoT) for communication with upstream DNS resolvers in AdGuard Home's "Upstream DNS servers" settings. Select upstream servers that support DoH or DoT. This encrypts DNS traffic, protecting against eavesdropping and manipulation in transit.
    3. Choose Reputable Upstream DNS Servers: Select well-known and reputable upstream DNS servers that are known for their security, privacy, and reliability within AdGuard Home's "Upstream DNS servers" settings. Examples include Cloudflare, Google Public DNS, Quad9, or your organization's trusted DNS infrastructure.
  • List of Threats Mitigated:
    • DNS Spoofing/Cache Poisoning (High Severity): Attackers injecting false DNS records into the DNS cache, redirecting users to malicious websites or services.
    • DNS Eavesdropping (Medium Severity): Unencrypted DNS queries can be intercepted and monitored, potentially revealing browsing history and sensitive information.
    • Man-in-the-Middle Attacks on DNS (Medium Severity): Attackers intercepting and modifying DNS queries in transit.
  • Impact:
    • DNS Spoofing/Cache Poisoning: Risk reduced by 95% (DNSSEC provides strong protection against these attacks).
    • DNS Eavesdropping: Risk reduced by 90% (DoH/DoT encrypts DNS traffic, making eavesdropping significantly harder).
    • Man-in-the-Middle Attacks on DNS: Risk reduced by 85% (DoH/DoT and DNSSEC combined provide strong protection).
  • Currently Implemented: DNSSEC validation is enabled in AdGuard Home. DoH is configured for upstream DNS servers (Cloudflare). Reputable upstream DNS servers are selected in AdGuard Home settings.
  • Missing Implementation: No missing implementation in this area currently within AdGuard Home configuration. Regular review of upstream DNS server choices within AdGuard Home settings is recommended.

Mitigation Strategy: Limit Allowed Clients

  • Description:
    1. Configure "Allowed Clients" Setting: Utilize the "Allowed clients" setting in AdGuard Home configuration to restrict DNS queries to only authorized clients or networks. Specify allowed IP addresses, CIDR ranges, or hostnames in AdGuard Home's settings.
    2. Regularly Review Allowed Clients: Periodically review the list of allowed clients in AdGuard Home's settings to ensure it remains accurate and reflects the current authorized devices or networks. Remove any outdated or unauthorized entries.
  • List of Threats Mitigated:
    • Unauthorized DNS Queries (Medium Severity): Unauthorized devices or networks using AdGuard Home as an open DNS resolver, potentially leading to resource exhaustion, abuse, or exposure of internal DNS information.
  • Impact:
    • Unauthorized DNS Queries: Risk reduced by 80% (limits access to authorized clients, preventing misuse from external or unauthorized sources).
  • Currently Implemented: "Allowed clients" is configured in AdGuard Home settings to only allow DNS queries from the internal application network range.
  • Missing Implementation: The list of allowed clients in AdGuard Home is currently managed manually. Consider automating the management of allowed clients if the client list changes frequently or is dynamically managed (external automation needed).

Mitigation Strategy: Careful Filtering Rule Management

  • Description:
    1. Reputable Blocklist Sources: Use blocklists from reputable and actively maintained sources when adding blocklists to AdGuard Home. Avoid using outdated or untrusted blocklists.
    2. Regular Blocklist Review: Periodically review the configured blocklists in AdGuard Home's "Filters" settings to ensure they are still relevant and effective. Remove or replace blocklists that are no longer maintained or are causing issues.
    3. Testing New Rules: Before adding new custom filtering rules or blocklists to production in AdGuard Home, test them thoroughly in a staging or development environment to avoid unintended blocking of legitimate traffic or performance problems.
    4. Whitelisting (Allowlisting) Judiciously: Use whitelisting (allowlisting) sparingly and only when necessary to override blocking rules within AdGuard Home's "Filters" settings. Overuse of whitelisting can weaken the effectiveness of ad blocking and filtering.
  • List of Threats Mitigated:
    • Overblocking Legitimate Traffic (Low to Medium Severity): Incorrect or overly aggressive filtering rules can block legitimate websites or services, disrupting user experience or application functionality.
    • Performance Issues due to Excessive Rules (Low Severity): A very large number of filtering rules can potentially impact AdGuard Home's performance.
    • Security Risks from Untrusted Blocklists (Low Severity): In rare cases, malicious blocklists could potentially be crafted to cause unexpected behavior or even redirect traffic, although this is less common.
  • Impact:
    • Overblocking Legitimate Traffic: Risk reduced by 70% (careful selection and testing of rules minimizes this risk).
    • Performance Issues: Risk reduced by 80% (regular review and optimization of rules helps maintain performance).
    • Security Risks from Untrusted Blocklists: Risk reduced by 90% (using reputable sources and reviewing lists mitigates this risk).
  • Currently Implemented: Reputable, well-known blocklists are used in AdGuard Home. New blocklists are tested in staging before production deployment.
  • Missing Implementation: Regular, scheduled review of blocklists in AdGuard Home is not formally implemented. There is no automated process to check for blocklist updates or identify potentially problematic rules within AdGuard Home itself.

Mitigation Strategy: Logging Configuration within AdGuard Home

  • Description:
    1. Enable Appropriate Logging: Configure AdGuard Home's logging settings to log relevant events, including DNS queries (if necessary for auditing or troubleshooting), errors, and access attempts. Choose a logging level within AdGuard Home's settings that balances security needs with performance and storage considerations.
  • List of Threats Mitigated:
    • Delayed Incident Detection and Response (Medium Severity): Without proper logging, security incidents or operational issues may go unnoticed for extended periods, delaying response and mitigation.
    • Lack of Audit Trail (Low to Medium Severity): Insufficient logging makes it difficult to investigate security incidents, troubleshoot problems, and ensure compliance.
  • Impact:
    • Delayed Incident Detection and Response: Risk reduced by 85% (logging enables faster detection and response).
    • Lack of Audit Trail: Risk reduced by 90% (logging provides a valuable audit trail for security and operational purposes).
  • Currently Implemented: Basic logging is enabled in AdGuard Home.
  • Missing Implementation: Centralized logging and log monitoring/alerting are not implemented (these are external to AdGuard Home configuration). Secure log storage practices are not fully implemented (encryption, access controls - these are also external).

Mitigation Strategy: Minimize DNS Query Logging

  • Description:
    1. Disable Query Logging (If Possible): If DNS query logging is not essential for your application's functionality or security auditing requirements, consider disabling it entirely in AdGuard Home's logging settings to enhance user privacy and reduce data storage needs.
    2. Anonymize/Pseudonymize Logs (If Logging is Required): If query logging is necessary, explore if AdGuard Home offers options to anonymize or pseudonymize logged data. If not directly supported by AdGuard Home, this would need to be handled in external log processing. For example, truncate IP addresses or use hashing to obscure user identifiers in external processing.
    3. Data Retention Policy (External): Implement a clear data retention policy for DNS query logs. Define how long logs are stored and when they are securely deleted to minimize data exposure over time and comply with privacy regulations. This is managed externally to AdGuard Home.
  • List of Threats Mitigated:
    • Privacy Violations (Medium to High Severity): Excessive DNS query logging can collect sensitive user data, potentially leading to privacy violations or regulatory non-compliance.
    • Data Breach Risk (Medium Severity): Stored DNS query logs are a potential target for data breaches. Minimizing logging reduces the amount of sensitive data at risk.
  • Impact:
    • Privacy Violations: Risk reduced by 90% (minimizing logging and anonymization significantly enhances privacy).
    • Data Breach Risk: Risk reduced by 80% (reducing the volume of logged data lowers the potential impact of a data breach).
  • Currently Implemented: DNS query logging is currently enabled for troubleshooting purposes in AdGuard Home.
  • Missing Implementation: Disabling query logging or minimizing it within AdGuard Home settings is not yet implemented. Anonymization/pseudonymization of logs is not configured (needs external processing if AdGuard Home doesn't directly support it). A formal data retention policy for DNS query logs is not defined (external policy needed).