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attack-surface.md

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Attack Surface Analysis for stackexchange/stackexchange.redis

Attack Surface: Unencrypted Connections

  • Description: Data transmitted between the application and the Redis server is sent in plain text, vulnerable to interception.
  • StackExchange.Redis Contribution: The library supports TLS/SSL but doesn't enforce it. It's the developer's responsibility to configure it correctly. Incorrect configuration (e.g., ignoring certificate errors) is a direct misuse of the library.
  • Example: An attacker uses a network sniffer to capture Redis commands and data, including sensitive information.
  • Impact: Data breach, unauthorized access to sensitive information.
  • Risk Severity: High (if sensitive data is involved).
  • Mitigation Strategies:
    • Developers: Always enable TLS/SSL in the StackExchange.Redis connection string (ssl=true). Configure SslProtocols and CertificateSelection correctly. Validate server certificates properly. Never disable certificate validation in production.

Attack Surface: Command Injection

  • Description: User-supplied data is directly incorporated into Redis commands without proper sanitization, allowing attackers to inject arbitrary Redis commands.
  • StackExchange.Redis Contribution: While the library's API encourages safe usage, it's still possible to construct raw commands unsafely using Execute or ExecuteAsync. This is a direct misuse of the library's features.
  • Example: An attacker injects FLUSHALL into a key name, causing all data in the Redis instance to be deleted.
  • Impact: Data loss, data corruption, denial of service, potential for server compromise (depending on injected command).
  • Risk Severity: Critical.
  • Mitigation Strategies:
    • Developers: Never concatenate user input directly into Redis commands. Use the provided API methods (e.g., StringSet, HashGet, etc.) which handle escaping automatically. Validate and sanitize all user input before using it in any Redis operation. Avoid constructing raw command strings and using Execute with unsanitized input.

Attack Surface: Lua Script Injection

  • Description: User-supplied data is used to construct Lua scripts executed on the Redis server, allowing attackers to inject malicious Lua code.
  • StackExchange.Redis Contribution: The library provides methods for executing Lua scripts (ScriptEvaluate). If user input is used unsafely within these scripts (passed directly to ScriptEvaluate without sanitization), it creates a direct injection vulnerability through the library.
  • Example: An attacker injects Lua code that iterates through all keys and exfiltrates their values.
  • Impact: Data exfiltration, data modification, denial of service, potential for server compromise.
  • Risk Severity: Critical.
  • Mitigation Strategies:
    • Developers: Avoid using user input directly in Lua scripts. If unavoidable, treat it as completely untrusted and sanitize it rigorously. Prefer pre-compiled Lua scripts. Use parameterized inputs with ScriptEvaluate whenever possible. Never pass unsanitized user input directly to ScriptEvaluate.

Attack Surface: Deserialization Vulnerabilities

  • Description: The application stores serialized objects in Redis, and the deserialization process is vulnerable to injection attacks.
  • StackExchange.Redis Contribution: While the library doesn't handle serialization itself, it facilitates storing and retrieving the serialized data. The vulnerability arises from how the application uses the library to store potentially unsafe data.
  • Example: An attacker crafts a malicious serialized object that, when retrieved using StringGet and then deserialized, executes arbitrary code.
  • Impact: Remote code execution (RCE) on the application server.
  • Risk Severity: Critical.
  • Mitigation Strategies:
    • Developers: Use secure serialization libraries. Avoid deserializing untrusted data retrieved from Redis. If possible, use a format with schema validation. Implement a whitelist of allowed types for deserialization.

Attack Surface: Connection Pool Exhaustion (DoS)

  • Description: The application fails to properly manage Redis connections, leading to exhaustion of the connection pool and a denial-of-service condition.
  • StackExchange.Redis Contribution: The library uses a connection pool, but improper usage (e.g., not disposing of ConnectionMultiplexer instances, or creating too many instances) directly leads to this vulnerability. This is a direct consequence of misusing the library's connection management.
  • Example: A bug causes the application to repeatedly create new ConnectionMultiplexer instances without disposing of them.
  • Impact: Denial of service; the application becomes unable to interact with Redis.
  • Risk Severity: High.
  • Mitigation Strategies:
    • Developers: Ensure proper disposal of ConnectionMultiplexer instances (use using statements or explicit Dispose() calls). Follow the recommended singleton pattern for ConnectionMultiplexer. Monitor connection pool usage and set appropriate limits. Implement robust error handling and retry logic.