attack-surface.md

Attack Surface Analysis for elastic/elasticsearch-net

Attack Surface: Data Injection through Query Parameters

Description: Attackers inject malicious code or commands into Elasticsearch queries by manipulating user-controlled input that is used to construct queries via elasticsearch-net. This occurs when application code fails to properly sanitize or parameterize user input before incorporating it into Elasticsearch queries built using elasticsearch-net's query building features. elasticsearch-net Contribution: elasticsearch-net provides flexible query building methods (e.g., QueryStringQuery, MatchQuery) that, if misused by directly embedding unsanitized user input, create injection points. Example: Application code uses elasticsearch-net to build a search query based on user input for product names:

var userInputProductName = GetUserInput(); // User input from request
var searchResponse = client.Search<Product>(s => s
    .Query(q => q
        .QueryString(qs => qs
            .Query(userInputProductName) // Unsanitized user input directly in query
        )
    )
);

An attacker could input a malicious string like Laptop OR _exists_:sensitive_field into userInputProductName. elasticsearch-net will execute this crafted query against Elasticsearch, potentially bypassing intended search logic and exposing sensitive data (sensitive_field) that should not be accessible. Impact: Unauthorized access to data, data modification, data deletion within Elasticsearch. In some configurations, it could potentially lead to limited command execution on the Elasticsearch server. Risk Severity: High Mitigation Strategies:

• Strict Input Sanitization and Validation: Thoroughly validate and sanitize all user inputs before they are used to construct Elasticsearch queries within elasticsearch-net. Use allow-lists and escape special characters relevant to Elasticsearch query syntax.
• Utilize Parameterized Queries and Query Builders: Leverage elasticsearch-net's query builder methods (e.g., MatchQuery, TermQuery, BoolQuery) which inherently handle input more safely than directly constructing query strings. Avoid using QueryStringQuery with unsanitized user input.
• Principle of Least Privilege (Elasticsearch User): Configure the Elasticsearch user used by elasticsearch-net with the minimum necessary permissions to limit the potential damage from a successful injection attack.

Attack Surface: Insecure Connection Configuration (HTTP)

Description: elasticsearch-net is configured to communicate with the Elasticsearch cluster over unencrypted HTTP. This exposes all communication, including potentially sensitive query data and Elasticsearch credentials, to eavesdropping and man-in-the-middle attacks. elasticsearch-net Contribution: elasticsearch-net's ConnectionSettings allows specifying the Elasticsearch endpoint URI. If the URI scheme is http:// instead of https://, elasticsearch-net will establish an unencrypted connection. Example: elasticsearch-net client is initialized with an HTTP endpoint:

var settings = new ConnectionSettings(new Uri("http://elasticsearch.example.com:9200")); // HTTP - Insecure
var client = new ElasticClient(settings);

All data transmitted between the application (using elasticsearch-net) and the Elasticsearch server, including query parameters, request bodies, and response data, is sent in plaintext over the network. Impact: Confidentiality breach - sensitive data transmitted to and from Elasticsearch can be intercepted. Credentials used for Elasticsearch authentication (if passed in the URI or headers) can be exposed. Potential for man-in-the-middle attacks to modify data in transit. Risk Severity: High Mitigation Strategies:

• Enforce HTTPS for Elasticsearch Connections: Always configure elasticsearch-net to use https:// in the Elasticsearch endpoint URI within ConnectionSettings.
• Enable TLS/SSL on Elasticsearch: Ensure the Elasticsearch cluster itself is configured to enforce TLS/SSL encryption for all incoming connections.
• Network Security Best Practices: Implement network security measures like firewalls and network segmentation to further protect the communication channel between the application and Elasticsearch.

Attack Surface: Exposed Elasticsearch Credentials

Description: Elasticsearch credentials required by elasticsearch-net for authentication are stored insecurely, making them easily accessible to attackers. This compromises the security of the Elasticsearch cluster. elasticsearch-net Contribution: elasticsearch-net's ConnectionSettings allows various methods for providing authentication credentials (e.g., BasicAuthentication, API keys). If these credentials are hardcoded directly in the application code or stored in easily accessible configuration files in plaintext, it creates a critical vulnerability. Example: Credentials hardcoded directly in the elasticsearch-net initialization:

var settings = new ConnectionSettings(new Uri("https://elasticsearch.example.com:9200"))
    .BasicAuthentication("elastic", "P@$$wOrd"); // Hardcoded credentials - Highly Insecure!
var client = new ElasticClient(settings);

Or credentials stored in a plain text configuration file committed to source control or accessible via web server misconfiguration. Impact: Complete compromise of the Elasticsearch cluster. Attackers can gain full administrative access, leading to unauthorized data access, modification, deletion, denial of service, and potentially further lateral movement within the infrastructure. Risk Severity: Critical Mitigation Strategies:

• Never Hardcode Credentials: Absolutely avoid hardcoding credentials directly in application code.
• Secure Credential Storage: Utilize secure methods for storing and retrieving Elasticsearch credentials:
  • Environment Variables: Store credentials as environment variables, accessed at runtime by the application.
  • Secrets Management Systems: Employ dedicated secrets management systems (e.g., HashiCorp Vault, Azure Key Vault, AWS Secrets Manager) to securely store, manage, and rotate credentials.
  • Encrypted Configuration: If configuration files are used, encrypt them and ensure secure decryption mechanisms are in place.
• Principle of Least Privilege (Credentials): Use dedicated service accounts with minimal necessary permissions for elasticsearch-net connections to Elasticsearch.
• Regular Credential Rotation: Implement a policy for regular rotation of Elasticsearch credentials.

Attack Surface: Dependency Vulnerabilities

Description: elasticsearch-net relies on third-party libraries (dependencies). Known vulnerabilities in these dependencies can be exploited through applications using elasticsearch-net, even if the application code itself is secure. elasticsearch-net Contribution: elasticsearch-net, like most .NET libraries, depends on NuGet packages. If these dependencies contain security vulnerabilities, they become part of the attack surface of any application using elasticsearch-net. Example: elasticsearch-net might depend on a specific version of a JSON serialization library that has a known deserialization vulnerability. If an attacker can control or influence data processed by elasticsearch-net that utilizes this vulnerable dependency (e.g., through crafted Elasticsearch responses or requests), they could potentially exploit the vulnerability. Impact: Impact varies depending on the specific dependency vulnerability. It can range from denial of service and information disclosure to remote code execution. Risk Severity: High (can be Critical depending on the vulnerability) Mitigation Strategies:

• Regular Dependency Scanning: Implement automated dependency scanning as part of the development and deployment pipeline. Use tools like OWASP Dependency-Check, Snyk, or GitHub Dependabot to identify known vulnerabilities in elasticsearch-net's dependencies.
• Keep Dependencies Updated: Proactively update elasticsearch-net and all its dependencies to the latest versions. Regularly monitor for security updates and patch releases for NuGet packages used by elasticsearch-net.
• Vulnerability Monitoring and Alerts: Subscribe to security advisories and vulnerability databases related to .NET and NuGet packages to stay informed about potential risks affecting elasticsearch-net's dependency chain.
• Software Composition Analysis (SCA): Integrate SCA tools into the development process to continuously monitor and manage the security risks associated with open-source dependencies.