attack-surface.md

Attack Surface Analysis for elastic/elasticsearch-php

Attack Surface: Elasticsearch Query Injection

• Description: A critical vulnerability where unsanitized user input is directly embedded into Elasticsearch queries constructed using elasticsearch-php. This allows attackers to manipulate the intended query logic, potentially leading to severe consequences.
• How elasticsearch-php Contributes: elasticsearch-php provides methods to build queries, including accepting raw arrays or strings for the query body. If developers directly concatenate user input into these raw query parts without proper sanitization or parameterization, they create a direct pathway for query injection. The library's flexibility in query construction becomes a risk when misused.
• Example:
  • Scenario: An application allows users to search products by name. Vulnerable code directly incorporates user input into a match query:

    $productName = $_GET['product_name']; // User input
    $params = [
        'index' => 'products',
        'body' => [
            'query' => [
                'match' => [
                    'name' => $productName // Direct user input injection
                ]
            ]
        ]
    ];
    $client->search($params);

  • Attack: An attacker crafts input like "* OR _exists_:_index" for product_name. This injected clause bypasses the product name search and could return documents from all indices, potentially exposing sensitive data from unrelated indices if permissions allow. In more sophisticated attacks, malicious aggregations or script queries could be injected.
• Impact:
  • Critical Data Breach: Unauthorized access to sensitive data across multiple indices within Elasticsearch.
  • Data Manipulation/Destruction: Ability to modify or delete data in Elasticsearch indices through malicious query construction.
  • Denial of Service: Crafting resource-intensive queries that overload the Elasticsearch cluster.
• Risk Severity: Critical
• Mitigation Strategies:
  • Mandatory Parameterized Queries: Force the use of elasticsearch-php's query builder or array-based query construction methods. Strictly avoid any direct string concatenation of user input into query bodies.
  • Strict Input Validation and Sanitization: Implement robust input validation to define allowed characters, data types, and lengths for user inputs used in queries. Sanitize or escape any special characters if absolutely necessary (though parameterized queries are the preferred approach).
  • Principle of Least Privilege (Elasticsearch Permissions): Configure Elasticsearch user roles and permissions used by the application to grant only the minimum necessary access. This limits the scope of damage even if query injection is successful.

Attack Surface: Misconfiguration Leading to Unencrypted Communication (HTTP)

• Description: A high-severity misconfiguration where the elasticsearch-php client is configured to communicate with Elasticsearch over unencrypted HTTP instead of HTTPS. This exposes sensitive data in transit to potential interception.
• How elasticsearch-php Contributes: elasticsearch-php's configuration allows specifying the transport protocol (HTTP or HTTPS) when defining Elasticsearch hosts. If developers incorrectly configure or default to HTTP, or fail to enforce HTTPS, the library will facilitate unencrypted communication.
• Example:
  • Scenario: elasticsearch-php client is initialized with a configuration like this, explicitly or implicitly using HTTP:

    $client = ClientBuilder::create()
        ->setHosts(['http://elasticsearch.example.com:9200']) // HTTP is specified
        ->build();

    Or if HTTPS is not explicitly configured when it should be.
  • Attack: All communication between the PHP application and Elasticsearch, including queries, data being indexed, and search results, is transmitted in plaintext over the network. Attackers on the network (e.g., through Man-in-the-Middle attacks) can intercept and read this sensitive data. This is especially critical in production environments or untrusted networks.
• Impact:
  • High Data Confidentiality Breach: Interception of sensitive data transmitted between the application and Elasticsearch, including potentially user data, application secrets, or internal system information.
  • Potential Data Manipulation: In some scenarios, attackers might not only intercept but also modify requests in transit if HTTP is used, though this is less common than simple interception.
• Risk Severity: High
• Mitigation Strategies:
  • Enforce HTTPS for All Elasticsearch Communication: Always configure the elasticsearch-php client to use HTTPS for all connections to Elasticsearch. Ensure Elasticsearch itself is also configured to support and enforce HTTPS.
  • Explicitly Configure HTTPS in Client: Clearly specify https:// in the host configuration when initializing the elasticsearch-php client.
  • Regular Configuration Review: Periodically review the elasticsearch-php client configuration to verify that HTTPS is correctly configured and enforced, especially after deployments or configuration changes.
  • Network Security Measures: Implement network security best practices, such as using secure networks and monitoring for suspicious network activity, to further reduce the risk of Man-in-the-Middle attacks.