CVE-2016-4977 in Spring Security OAuth
Summary
by MITRE
When processing authorization requests using the whitelabel views in Spring Security OAuth 2.0.0 to 2.0.9 and 1.0.0 to 1.0.5, the response_type parameter value was executed as Spring SpEL which enabled a malicious user to trigger remote code execution via the crafting of the value for response_type.
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Analysis
by VulDB Data Team • 10/03/2020
The vulnerability identified as CVE-2016-4977 represents a critical remote code execution flaw within Spring Security OAuth implementations that affected versions ranging from 2.0.0 through 2.0.9 and 1.0.0 through 1.0.5. This vulnerability stems from improper input validation and sanitization within the authorization request processing mechanism, specifically when utilizing whitelabel views. The core issue manifests in how the framework handles the response_type parameter during OAuth authorization flows, creating a dangerous execution path that allows attackers to inject malicious Spring Expression Language expressions directly into the application's processing pipeline.
The technical exploitation of this vulnerability occurs through the manipulation of the response_type parameter value, which is processed as Spring SpEL (Spring Expression Language) expressions rather than being properly sanitized or validated. When a malicious actor crafts a specially designed response_type parameter containing executable SpEL code, the Spring Security framework inadvertently executes this code within the application context, providing attackers with remote code execution capabilities. This flaw directly maps to CWE-94, which describes the execution of code from untrusted sources, and represents a classic case of insecure deserialization combined with improper input validation. The vulnerability leverages the legitimate Spring framework capabilities to execute arbitrary code, making it particularly dangerous as it operates within the normal application flow without raising immediate suspicion.
The operational impact of CVE-2016-4977 is severe and far-reaching, as it allows attackers to gain complete control over affected systems. Once exploited, malicious users can execute arbitrary commands on the server, potentially leading to data breaches, system compromise, and full network infiltration. The vulnerability affects organizations using Spring Security OAuth implementations in production environments, creating a significant risk for applications handling sensitive authentication and authorization processes. This vulnerability directly aligns with ATT&CK technique T1059.007, which covers the execution of malicious code through script interpreters, and represents a critical weakness in the application's input validation controls. The impact extends beyond immediate system compromise to include potential credential theft, privilege escalation, and lateral movement within network environments.
Organizations affected by this vulnerability should immediately implement mitigations including updating to patched versions of Spring Security OAuth, implementing proper input validation and sanitization for all authorization parameters, and deploying web application firewalls to detect and block malicious response_type parameter values. The recommended remediation strategy involves upgrading to Spring Security OAuth versions 2.0.10 and 1.0.6 or later, which contain the necessary fixes for the SpEL execution vulnerability. Additionally, security teams should implement comprehensive monitoring of authorization request parameters and establish strict validation rules to prevent any unauthorized execution of expression language within the application framework. The vulnerability highlights the critical importance of validating all user inputs, particularly those used in framework-level processing, and demonstrates the potential consequences of inadequate input sanitization in authentication and authorization systems.