Skip to content

Latest commit

 

History

History
79 lines (64 loc) · 8.03 KB

attack-surface.md

File metadata and controls

79 lines (64 loc) · 8.03 KB

Attack Surface Analysis for adguardteam/adguardhome

Attack Surface: DNS Cache Poisoning (Targeting AdGuard Home's Resolver)

  • Description: An attacker injects forged DNS records into AdGuard Home's cache, causing it to return incorrect IP addresses for domain names.
  • AdGuard Home Contribution: AdGuard Home acts as a recursive DNS resolver, making its cache a target. Vulnerabilities in its DNS handling logic are the key concern.
  • Example: An attacker sends specially crafted DNS responses to AdGuard Home, causing it to cache a malicious IP address for bank.com.
  • Impact: Users are redirected to a phishing site, potentially leading to credential theft or malware infection.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Developers): Rigorous input validation and sanitization of DNS responses within the resolver. Thorough testing for cache poisoning vulnerabilities. Ensure DNSSEC validation is correctly implemented and robust.
    • (Users): Keep AdGuard Home updated to the latest version. Use reputable upstream DNS servers with DoT/DoH enabled. Monitor for unusual DNS resolution behavior.

Attack Surface: Upstream DNS Server Compromise

  • Description: An attacker compromises or manipulates one of the upstream DNS servers that AdGuard Home uses.
  • AdGuard Home Contribution: AdGuard Home relies on external DNS servers for resolution. It's a conduit for the compromised data, and its configuration choices directly impact this risk.
  • Example: An attacker compromises a public DNS server, causing it to return malicious records. AdGuard Home, using that server, propagates the malicious data.
  • Impact: Widespread redirection of traffic to malicious sites, affecting all users relying on AdGuard Home.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Developers): Provide clear guidance and tools for users to configure multiple, diverse, and trusted upstream servers. Promote the use of DoT/DoH and make configuration straightforward.
    • (Users): Use a diverse set of reputable upstream DNS servers (e.g., Quad9, Cloudflare, Google). Enable DoT/DoH for all upstream connections. Avoid relying solely on a single provider.

Attack Surface: Filter List Poisoning/Manipulation

  • Description: An attacker provides a malicious filter list to AdGuard Home, causing it to block legitimate sites or allow malicious ones.
  • AdGuard Home Contribution: AdGuard Home's core function is to apply filter lists to DNS queries. The mechanism for fetching and applying lists is the attack surface, directly within AdGuard Home's control.
  • Example: An attacker compromises a filter list provider, inserting rules that block access to security update servers or allow access to known phishing domains.
  • Impact: Disruption of legitimate services, increased exposure to malware, or circumvention of security controls.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Developers): Implement integrity checks (e.g., checksums, signatures) for downloaded filter lists. Provide a curated list of trusted filter list sources. Implement robust error handling for malformed filter lists.
    • (Users): Use only reputable and well-maintained filter list sources. Be cautious about adding custom filter lists from untrusted sources. Monitor for unexpected blocking or allowing of websites.

Attack Surface: Authentication Bypass (Web Interface/API)

  • Description: An attacker gains unauthorized access to AdGuard Home's web interface or API, bypassing authentication.
  • AdGuard Home Contribution: AdGuard Home provides a web interface and API for management. Vulnerabilities in these interfaces' authentication mechanisms are the concern, directly within AdGuard Home's code.
  • Example: An attacker exploits a vulnerability in the web interface's login form to gain administrative access.
  • Impact: Complete control over AdGuard Home's configuration, allowing the attacker to redirect traffic, disable filtering, or exfiltrate data.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Developers): Implement strong authentication mechanisms (e.g., using well-vetted libraries). Enforce strong password policies. Implement multi-factor authentication (MFA). Regularly audit the authentication code. Rate-limit login attempts.
    • (Users): Use strong, unique passwords. Enable MFA if available. Consider placing the web interface behind a reverse proxy with additional security measures.

Attack Surface: API Abuse/Configuration Manipulation

  • Description: An attacker uses the AdGuard Home API to modify its configuration without authorization.
  • AdGuard Home Contribution: The API provides programmatic access to AdGuard Home's functionality. Weaknesses in API security are the issue, directly within AdGuard Home's design and implementation.
  • Example: An attacker discovers an exposed API key and uses it to add malicious entries to the filter lists.
  • Impact: Similar to authentication bypass – control over DNS resolution, filtering, and settings.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Developers): Secure API keys and authentication. Implement strict access controls and authorization for API endpoints. Validate all API input. Implement rate limiting.
    • (Users): Protect API keys carefully. Regularly review API usage logs.

Attack Surface: Denial-of-Service (DoS) against AdGuard Home

  • Description: An attacker floods AdGuard Home with requests, making it unresponsive and disrupting DNS resolution for the network.
  • AdGuard Home Contribution: AdGuard Home is the central DNS server. Its availability is critical, and its internal handling of requests determines its resilience to DoS.
  • Example: An attacker sends a large number of DNS queries to AdGuard Home, overwhelming its resources.
  • Impact: Loss of DNS resolution, preventing users from accessing the internet.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Developers): Implement rate limiting for DNS queries, API requests, and web interface access. Optimize code for performance and resource usage. Implement robust error handling.
    • (Users): Configure a firewall to limit incoming DNS traffic to trusted sources. Monitor AdGuard Home's resource usage. Consider using a load balancer or other infrastructure to improve resilience (although this is less direct involvement).

Attack Surface: Dependency Vulnerabilities

  • Description: Vulnerabilities in third-party libraries or components used by AdGuard Home.
  • AdGuard Home Contribution: AdGuard Home, like any software, relies on external dependencies. The choice and management of these dependencies are directly within the AdGuard Home project's control.
  • Example: A vulnerability is discovered in a networking library used by AdGuard Home, allowing for remote code execution.
  • Impact: Varies depending on the specific vulnerability, but could range from information disclosure to complete system compromise.
  • Risk Severity: High to Critical (depending on the dependency vulnerability)
  • Mitigation Strategies:
    • (Developers): Regularly update dependencies to their latest secure versions. Use software composition analysis (SCA) tools to identify and track vulnerable dependencies. Implement a robust vulnerability management process.
    • (Users): Keep AdGuard Home updated to the latest version, which should include updated dependencies.