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attack-surface.md

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Attack Surface Analysis for mengto/spring

Attack Surface: Mass Assignment / Over-Posting

  • Description: Attackers manipulate HTTP requests to modify object properties they shouldn't have access to, bypassing intended restrictions.
    • Spring Contribution: Spring's automatic data binding (mapping request parameters to object fields) directly enables this attack if not properly configured. This is a core Spring feature.
    • Example: A user updates their profile. The form only allows changing name and email. An attacker adds &isAdmin=true to the request, potentially gaining administrative privileges if the User object has an isAdmin field and no protection (via Spring's mechanisms) is in place.
    • Impact: Unauthorized data modification, privilege escalation, bypassing security controls.
    • Risk Severity: High (can be Critical depending on the data).
    • Mitigation Strategies:
      • Use DTOs (Data Transfer Objects): Create separate classes (DTOs) that represent only the data needed for a specific operation. This is the best practice and directly addresses the Spring data binding issue.
      • @ModelAttribute with Allowed/Disallowed Fields: Use WebDataBinder.setAllowedFields() or WebDataBinder.setDisallowedFields() within a @Controller's @InitBinder method. This is a Spring-specific mitigation.
      • Input Validation (with Spring's Framework): While input validation is generally important, using Spring's validation framework (@Valid, @Validated, custom validators) helps ensure data conforms to expected types before Spring's data binding occurs.

Attack Surface: SpEL Injection (Spring Expression Language)

  • Description: Attackers inject malicious SpEL code into user-controllable input that is then evaluated by the Spring Framework.
    • Spring Contribution: SpEL is a core component of the Spring Framework, used extensively. This vulnerability is entirely due to Spring's SpEL feature.
    • Example: A forum application uses SpEL in a Thymeleaf template (which integrates deeply with Spring) to display user-provided content: <span th:text="${user.profile.bio}"></span>. An attacker enters a "bio" containing: ${T(java.lang.Runtime).getRuntime().exec('rm -rf /')}. If not properly escaped (using Spring's escaping utilities), this executes arbitrary code.
    • Impact: Remote Code Execution (RCE), complete system compromise.
    • Risk Severity: Critical.
    • Mitigation Strategies:
      • Avoid User Input in SpEL: The primary mitigation is to never directly incorporate user-supplied data into SpEL expressions. This is a direct recommendation related to Spring's SpEL usage.
      • Strict Whitelisting (if unavoidable): If user input must be used, implement extremely strict whitelisting.
      • Context-Aware Escaping (using Spring Utilities): Use Spring's HtmlUtils.htmlEscape (for HTML contexts within Thymeleaf, a Spring-integrated technology) or JavaScriptUtils.javaScriptEscape.

Attack Surface: Spring Security Misconfiguration

  • Description: Incorrect or weak configuration of Spring Security features, leading to authentication or authorization bypass.
    • Spring Contribution: This vulnerability is directly related to the configuration of the Spring Security framework itself.
    • Example: Disabling CSRF protection (a Spring Security feature) without a valid reason. Using overly permissive hasRole expressions in Spring Security's @PreAuthorize annotations.
    • Impact: Authentication bypass, authorization bypass, unauthorized access.
    • Risk Severity: High to Critical (depending on the specific misconfiguration).
    • Mitigation Strategies:
      • Follow Spring Security Best Practices: Adhere strictly to Spring Security's documentation.
      • Enable CSRF Protection (Spring Security Feature): Unless a specific, well-understood exception exists (and alternative Spring-based protections are in place), CSRF protection should always be enabled. This is a direct Spring Security configuration.
      • Principle of Least Privilege (within Spring Security): Configure authorization rules (using Spring Security annotations and configurations) to grant only the minimum necessary permissions.
      • Regular Audits of Spring Security Configuration: Regularly review the Spring Security setup.

Attack Surface: Actuator Endpoint Exposure

  • Description: Exposing Spring Boot Actuator endpoints to the public internet without proper security.
    • Spring Contribution: Actuator is a core feature of Spring Boot, providing these management endpoints. The vulnerability arises from exposing these Spring-provided endpoints.
    • Example: Accessing /actuator/env (a Spring Boot Actuator endpoint) reveals environment variables. /actuator/heapdump allows downloading a heap dump.
    • Impact: Sensitive information disclosure.
    • Risk Severity: High to Critical.
    • Mitigation Strategies:
      • Restrict Network Access: Limit access to Spring Boot Actuator endpoints.
      • Authentication and Authorization (using Spring Security): Use Spring Security to protect Actuator endpoints.
      • Disable Unnecessary Endpoints (Spring Boot Configuration): Disable endpoints that are not needed using Spring Boot's management.endpoints.web.exposure.exclude property. This is a direct Spring Boot configuration setting.
      • Separate Port (Spring Boot Configuration): Use a separate port for Actuator endpoints via Spring Boot configuration.

Attack Surface: Insecure Deserialization

  • Description: Deserializing untrusted data using Java's built-in serialization mechanism can lead to arbitrary code execution.
    • Spring Contribution: While not exclusively a Spring issue, Spring applications, particularly older ones or those using technologies like RMI or Spring's remoting capabilities, might be more prone to using Java serialization. Spring's ecosystem and historical use patterns contribute to the potential presence of this vulnerability.
    • Example: A Spring application using RMI (Remote Method Invocation) receives a serialized Java object from an untrusted client. The object contains a malicious payload that is executed upon deserialization.
    • Impact: Remote Code Execution (RCE), complete system compromise.
    • Risk Severity: Critical.
    • Mitigation Strategies:
      • Avoid Untrusted Deserialization: The primary mitigation is to avoid deserializing data from untrusted sources.
      • Whitelist Approach: If deserialization is unavoidable, use a strict whitelist to allow only specific, known-safe classes to be deserialized.
      • Alternative Serialization (with Spring Support): Consider using safer serialization formats like JSON (with libraries like Jackson, often used with Spring) or Protocol Buffers, which have better security characteristics. Spring provides excellent support for these alternatives.
      • Look-Ahead Deserialization: Implement look-ahead deserialization techniques to inspect the object stream before fully deserializing it.