CVE-2018-15758 in Spring Security OAuth
Summary
by MITRE
Spring Security OAuth, versions 2.3 prior to 2.3.4, and 2.2 prior to 2.2.3, and 2.1 prior to 2.1.3, and 2.0 prior to 2.0.16, and older unsupported versions could be susceptible to a privilege escalation under certain conditions. A malicious user or attacker can craft a request to the approval endpoint that can modify the previously saved authorization request and lead to a privilege escalation on the subsequent approval. This scenario can happen if the application is configured to use a custom approval endpoint that declares AuthorizationRequest as a controller method argument. This vulnerability exposes applications that meet all of the following requirements: Act in the role of an Authorization Server (e.g. @EnableAuthorizationServer) and use a custom Approval Endpoint that declares AuthorizationRequest as a controller method argument. This vulnerability does not expose applications that: Act in the role of an Authorization Server and use the default Approval Endpoint, act in the role of a Resource Server only (e.g. @EnableResourceServer), act in the role of a Client only (e.g. @EnableOAuthClient).
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Analysis
by VulDB Data Team • 05/30/2023
Spring Security OAuth framework versions prior to specific patched releases contain a critical privilege escalation vulnerability that stems from improper handling of authorization requests within custom approval endpoints. The vulnerability exists when applications configure custom approval endpoints that accept AuthorizationRequest as a method argument while operating as authorization servers. This flaw allows malicious actors to manipulate authorization requests through crafted HTTP requests to the approval endpoint, potentially enabling unauthorized access to protected resources. The technical mechanism relies on the framework's failure to properly validate and sanitize authorization request parameters when they are passed through custom controller methods, creating an injection vector for privilege escalation attacks.
The vulnerability operates within the OAuth 2.0 authorization framework where applications function as authorization servers and implement custom approval logic. When a custom approval endpoint declares AuthorizationRequest as a controller method parameter, the framework deserializes and processes this object without adequate input validation. Attackers can exploit this by crafting malicious requests that modify the authorization request data structure, effectively changing the scope, permissions, or target resources of the original authorization request. This manipulation occurs during the approval process where users are prompted to grant permissions, allowing attackers to escalate their privileges by altering the authorization context before final approval. The vulnerability specifically affects applications using the @EnableAuthorizationServer annotation and implementing custom approval endpoints, making it particularly dangerous for enterprise applications that require fine-grained access control.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially compromise entire authorization systems within affected applications. An attacker who successfully exploits this vulnerability could gain access to resources they should not be authorized to access, potentially leading to data breaches, unauthorized system modifications, or complete compromise of the authorization infrastructure. The attack requires specific application configurations to be effective, limiting its scope but making it particularly dangerous for applications that implement custom approval logic. Organizations running affected versions of Spring Security OAuth must consider the potential for cascading effects, as successful exploitation could allow attackers to move laterally within systems that rely on proper authorization controls. The vulnerability's impact is further amplified because it operates at the authorization layer, meaning that compromised applications could affect multiple downstream services that depend on proper authorization decisions.
Organizations should immediately upgrade to patched versions of Spring Security OAuth, specifically versions 2.3.4, 2.2.3, 2.1.3, and 2.0.16 respectively, to mitigate this vulnerability. The recommended mitigation strategy includes implementing proper input validation and sanitization for all custom approval endpoints, particularly those that accept AuthorizationRequest objects as method parameters. Security teams should review all custom approval endpoint implementations to ensure they do not inadvertently expose the vulnerability through improper parameter handling. Additionally, organizations should conduct comprehensive security assessments of their OAuth implementations to identify any other potential injection vectors or authorization bypass opportunities. The vulnerability aligns with CWE-20 Improper Input Validation and follows ATT&CK technique T1078 Valid Accounts, as it allows attackers to escalate privileges through manipulation of legitimate authorization processes. Organizations should also consider implementing additional monitoring and logging around authorization server endpoints to detect potential exploitation attempts and establish proper incident response procedures for authorization-related security events.