Attack Surface: 1. Network Topology Discovery
- Description: An attacker attempts to learn about the internal network structure by observing the application's behavior related to reachability checks.
- How Reachability Contributes: The library's core function is to test reachability to specific hosts, making it a direct tool for network probing if misused.
- Example: An attacker observes that the application's UI shows "Offline" when they try to access a feature, and the error message (or timing) reveals that the application is attempting to reach
internal-db.example.com. - Impact: Leaked information about internal network structure can be used to plan further attacks, identify vulnerable services, and bypass perimeter defenses.
- Risk Severity: High
- Mitigation Strategies:
- Abstraction: Do not expose raw reachability results or target hostnames to the user. Use generic status indicators (e.g., "Service Unavailable").
- Rate Limiting: Implement strict rate limiting on any user-facing features that trigger reachability checks.
- Generic Targets: Use generic hostnames or IP addresses for reachability checks when possible (e.g., a gateway address instead of a specific database server).
- Logging and Monitoring: Log all reachability check targets and results, and monitor for unusual patterns or probes.
Attack Surface: 2. DNS Spoofing/Hijacking Amplification
- Description: An attacker manipulates DNS resolution to redirect reachability checks to a malicious host, potentially leading to data exfiltration or further compromise.
- How Reachability Contributes: If the library uses hostnames, it relies on DNS. The application's reaction to the (spoofed) reachability result is the key vulnerability.
- Example: An attacker poisons the DNS cache to point
api.example.comto their server. The application, believing the API is "reachable" (because the attacker's server responds), sends sensitive data to the attacker. - Impact: Data breaches, man-in-the-middle attacks, and potential compromise of the application or connected services.
- Risk Severity: High
- Mitigation Strategies:
- IP Addresses: Use IP addresses instead of hostnames for critical reachability checks whenever feasible.
- DNSSEC: Implement DNSSEC to validate DNS responses and prevent spoofing.
- Trusted Resolver: Use a dedicated, trusted DNS resolver for reachability checks.
- Certificate Pinning (if applicable): If the application communicates with a specific service after the reachability check, use certificate pinning to ensure it's talking to the legitimate server, even if DNS is compromised.
- Monitor DNS Resolution: Monitor DNS resolution times and failures for anomalies.