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attack-surface.md

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Attack Surface Analysis for duendesoftware/products

Attack Surface: Open Redirect Vulnerabilities in Authorization Endpoint

  • Description: Attackers can manipulate the redirect_uri parameter in the authorization request to redirect users to a malicious website after successful authentication due to insufficient validation within Duende IdentityServer's redirect URI handling.
  • How Products Contributes to Attack Surface: Duende IdentityServer's authorization endpoint and its redirect URI validation logic are the components directly responsible for preventing open redirects. Weaknesses here are product-specific attack surfaces.
  • Example: An attacker crafts a malicious authorization URL targeting Duende IdentityServer with a redirect_uri pointing to attacker.com. If Duende IdentityServer's validation logic is bypassed (e.g., due to overly permissive wildcard configurations or flaws in URI parsing), the user authenticates successfully but is then redirected to attacker.com, potentially leading to credential theft or malware installation.
  • Impact: Credential theft, malware distribution, phishing attacks, account compromise.
  • Risk Severity: High
  • Mitigation Strategies:
    • Strict Redirect URI Validation in IdentityServer Configuration: Configure clients in Duende IdentityServer with a precise whitelist of allowed redirect URIs. Avoid wildcard URIs unless absolutely necessary and with extreme caution.
    • Regularly Review Redirect URI Configurations: Audit client configurations in Duende IdentityServer to ensure redirect URIs are accurate and minimize the attack surface.
    • Implement Robust URI Parsing and Validation Logic (Product Improvement): Duende IdentityServer developers should ensure robust and secure URI parsing and validation logic within the product itself to prevent bypasses.

Attack Surface: Client Secret Exposure and Brute-forcing

  • Description: Weak or default client secrets configured within Duende IdentityServer for confidential clients can be easily guessed or brute-forced, allowing attackers to impersonate legitimate clients and obtain access tokens from Duende IdentityServer.
  • How Products Contributes to Attack Surface: Duende IdentityServer relies on client secrets for authenticating confidential clients at the token endpoint. The product's configuration and handling of these secrets directly contribute to this attack surface.
  • Example: A developer, during initial setup of Duende IdentityServer, uses a weak or default client secret (e.g., "secret", "password") for a confidential client. An attacker, through reconnaissance or by guessing common defaults, discovers this weak secret and uses it to directly request access tokens from Duende IdentityServer's token endpoint, bypassing intended authorization flows and gaining unauthorized access to protected resources.
  • Impact: Unauthorized access to protected resources, data breaches, impersonation of legitimate applications, complete compromise of client identity.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Enforce Strong Client Secret Generation: Duende IdentityServer administrators should enforce the generation of strong, randomly generated client secrets during client registration. The product itself could provide tools or guidance for this.
    • Secure Secret Storage Practices: Developers and operators must store client secrets securely, utilizing secure configuration management, secrets vaults, or encrypted storage mechanisms outside of easily accessible configuration files.
    • Secret Rotation Policies: Implement and enforce policies for regular rotation of client secrets within Duende IdentityServer configurations to limit the lifespan of potentially compromised secrets.
    • Consider Stronger Client Authentication Methods (Product Feature Consideration): For highly sensitive clients, consider utilizing stronger client authentication methods supported by Duende IdentityServer, such as client certificates or mutual TLS, to reduce reliance on shared secrets.

Attack Surface: SQL Injection Vulnerabilities in Custom Data Stores (If Applicable)

  • Description: If custom data stores are implemented as extensions to Duende IdentityServer (e.g., custom user stores, client stores) and these implementations involve direct database queries without proper input sanitization, SQL injection vulnerabilities can be introduced.
  • How Products Contributes to Attack Surface: Duende IdentityServer's extensibility model allows for custom data store implementations. If developers create these extensions insecurely, it becomes an attack surface stemming from the product's extensibility features. While not a core product vulnerability, it's a risk directly related to how the product is extended.
  • Example: A developer creates a custom user store for Duende IdentityServer that directly constructs SQL queries based on username input without using parameterized queries or proper sanitization. An attacker exploits this by injecting malicious SQL code through the username field during login, potentially bypassing authentication, extracting sensitive data from the database managed by the custom store, or even gaining control over the database server.
  • Impact: Data breaches, data manipulation, unauthorized access, privilege escalation, potential compromise of the underlying database infrastructure.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Promote Secure Coding Practices in Extension Development (Product Guidance): Duende IdentityServer documentation and developer resources should strongly emphasize secure coding practices for custom extensions, particularly regarding database interactions, highlighting the risks of SQL injection.
    • Mandatory Use of Parameterized Queries/ORMs in Custom Data Stores: Developers creating custom data stores for Duende IdentityServer must be required to use parameterized queries or ORMs to interact with databases, effectively preventing SQL injection.
    • Code Review and Security Audits for Custom Extensions: Thorough code reviews and security audits should be performed on all custom data store extensions for Duende IdentityServer before deployment to identify and remediate potential SQL injection vulnerabilities.
    • Input Validation and Sanitization in Custom Extensions: Even with parameterized queries, implement input validation and sanitization within custom extensions as a defense-in-depth measure.

Attack Surface: Misconfiguration Leading to Excessive Scope Granting

  • Description: Incorrect configuration of clients or resources within Duende IdentityServer can result in clients being granted overly broad scopes, providing them with access to more APIs or user data than intended or necessary. This expands the potential impact if a client is compromised.
  • How Products Contributes to Attack Surface: Duende IdentityServer's configuration system for clients and resources directly controls scope granting. Misconfigurations within this system are product-related vulnerabilities.
  • Example: A client in Duende IdentityServer is mistakenly configured to request and receive the "admin" scope, which grants access to sensitive administrative APIs. If this client (or an application using it) is compromised through other means (e.g., XSS, supply chain attack), the attacker can leverage this excessive scope to gain administrative privileges and further compromise the system.
  • Impact: Privilege escalation, unauthorized access to sensitive APIs and data, increased impact of client compromise, potential for wider system compromise.
  • Risk Severity: High
  • Mitigation Strategies:
    • Principle of Least Privilege in Scope Configuration: Configure clients and resources in Duende IdentityServer with the minimum necessary scopes required for their intended functionality. Avoid granting broad or administrative scopes unless absolutely essential and justified.
    • Regular Scope Configuration Audits: Periodically review and audit client and resource configurations within Duende IdentityServer to identify and rectify any instances of overly permissive scope granting.
    • Granular Scope Definition and Management (Product Feature): Duende IdentityServer should provide features for defining and managing scopes in a granular and easily understandable manner, making it easier for administrators to adhere to the principle of least privilege.
    • Automated Scope Validation and Policy Enforcement: Implement automated checks and policies within Duende IdentityServer configuration management to validate scope configurations against security best practices and prevent overly permissive grants.