threat-modeling.md

Threat Model Analysis for tonymillion/reachability

Threat: Threat: Network Topology Enumeration via Hostname Probing

• Description: An attacker provides a series of different hostnames or IP addresses to the application's interface that utilizes the reachability library. The attacker observes the application's responses (either directly or through timing analysis) to determine which hosts are reachable and which are not. This allows the attacker to map out accessible networks, infer firewall rules, and potentially discover internal network resources.
• Impact:
  • Disclosure of internal network structure.
  • Identification of vulnerable services on reachable hosts.
  • Information gathering for further attacks.
• Reachability Component Affected:
  • The core reachability checking function (e.g., a function like isReachable(hostname) or similar). This is the primary entry point for checking reachability.
  • Potentially any wrapper functions or classes that expose this core functionality.
• Risk Severity: High
• Mitigation Strategies:
  • Whitelist Allowed Hosts: Implement a strict whitelist of allowed hostnames or IP addresses. Reject any input that is not on the whitelist.
  • Obfuscate Results: Do not directly expose the raw reachability result (true/false). Return a generic "available" or "unavailable" status.
  • Introduce Delays: Add consistent, artificial delays to all responses, regardless of reachability status, to prevent timing attacks.
  • Rate Limiting: Limit the number of reachability checks per user/IP address within a given time period.

Threat: Threat: Resource Exhaustion via Repeated Checks

• Description: An attacker repeatedly triggers reachability checks, either to the same host or to a large number of different hosts. This consumes resources on the device (CPU, memory, battery) and potentially on the network.
• Impact:
  • Denial of service (DoS) for legitimate reachability checks.
  • Reduced application performance.
  • Increased battery drain (on mobile devices).
  • Network congestion.
• Reachability Component Affected:
  • The core reachability checking function (e.g., isReachable(hostname)).
  • Any internal queuing or scheduling mechanisms within the library.
• Risk Severity: High
• Mitigation Strategies:
  • Strict Rate Limiting: Implement very strict rate limiting, both per client and globally, on the number of reachability checks allowed.
  • Queue Management: Use a queue to manage reachability requests, limiting the number of concurrent checks.
  • Timeouts: Set reasonable timeouts for reachability checks to prevent them from running indefinitely.
  • Resource Monitoring: Monitor resource usage and alert on unusual spikes.

Threat: Threat: Exploitation of Library Bugs (e.g., Memory Corruption)

• Description: An attacker exploits a bug in the reachability library itself, such as a buffer overflow or memory leak, to cause a crash, execute arbitrary code, or gain unauthorized access. This is less likely with a well-maintained library, but still a possibility.
• Impact:
  • Application crash (DoS).
  • Potential arbitrary code execution (in severe cases).
  • Compromise of the application or device.
• Reachability Component Affected:
  • Potentially any part of the library, depending on the specific bug. This could be in the core reachability logic, the network interaction code, or the error handling routines.
• Risk Severity: Critical (if a code execution vulnerability exists), otherwise High.
• Mitigation Strategies:
  • Keep the Library Updated: Regularly update the reachability library to the latest version to receive bug fixes and security patches.
  • Dependency Auditing: Use tools to scan for known vulnerabilities in the library and its dependencies. Although this is an indirect threat via dependencies, keeping the library updated is a direct action to mitigate vulnerabilities within the library itself.
  • Fuzzing (Advanced): Consider fuzzing the library's input to identify potential vulnerabilities.
  • Code Review (Advanced): If feasible, review the library's source code for potential security issues.
  • Sandboxing (Advanced): Isolate reachability checks in a sandboxed environment.