CVE-2011-2894 in SpringSource Spring Security
Summary
by MITRE
Spring Framework 3.0.0 through 3.0.5, Spring Security 3.0.0 through 3.0.5 and 2.0.0 through 2.0.6, and possibly other versions deserialize objects from untrusted sources, which allows remote attackers to bypass intended security restrictions and execute untrusted code by (1) serializing a java.lang.Proxy instance and using InvocationHandler, or (2) accessing internal AOP interfaces, as demonstrated using deserialization of a DefaultListableBeanFactory instance to execute arbitrary commands via the java.lang.Runtime class.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability identified as CVE-2011-2894 represents a critical deserialization flaw affecting multiple versions of the Spring Framework and Spring Security libraries. This vulnerability resides in the object serialization and deserialization mechanisms within these widely-used enterprise Java frameworks, creating a significant attack surface that can be exploited by remote adversaries. The flaw specifically impacts versions 3.0.0 through 3.0.5 of Spring Framework, 3.0.0 through 3.0.5 and 2.0.0 through 2.0.6 of Spring Security, and potentially other affected versions, making it a widespread concern across enterprise application environments that rely on these components.
The technical implementation of this vulnerability stems from the improper handling of serialized objects within the Spring framework's object serialization pipeline. Attackers can exploit this weakness by crafting malicious serialized objects that, when processed by the vulnerable system, trigger unintended code execution. The exploit demonstrates two primary attack vectors: the first involves serializing a java.lang.Proxy instance with a custom InvocationHandler that can execute arbitrary code when the proxy object is deserialized. The second vector leverages access to internal AOP (Aspect-Oriented Programming) interfaces, specifically utilizing the DefaultListableBeanFactory instance to gain access to the java.lang.Runtime class and execute arbitrary commands on the target system. This represents a classic deserialization vulnerability where untrusted input is processed without proper validation or sanitization.
The operational impact of CVE-2011-2894 is severe and far-reaching, as it allows remote attackers to bypass intended security restrictions and execute arbitrary code on affected systems. This vulnerability can lead to complete system compromise, data exfiltration, and unauthorized access to sensitive information within enterprise environments. The attack requires minimal privileges to initiate, making it particularly dangerous as it can be exploited through network-based attacks without requiring physical access or prior authentication. Systems running vulnerable versions of Spring Framework or Spring Security are at risk of being fully compromised, potentially allowing attackers to establish persistent backdoors, escalate privileges, or use the compromised system as a launch point for further attacks against internal networks.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to patched versions of Spring Framework and Spring Security, implementing proper input validation for serialized objects, and restricting network access to affected systems. The vulnerability aligns with CWE-502, which describes "Deserialization of Untrusted Data" as a critical weakness in software systems. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control through deserialization attacks and privilege escalation via code execution. Additional protective measures should include network segmentation, monitoring for unusual deserialization patterns, and implementing application-level firewalls to prevent unauthorized deserialization operations. The security community has classified this vulnerability as high-risk due to its remote exploitability and potential for complete system compromise, emphasizing the critical need for immediate remediation across affected enterprise environments.