CVE-2017-9787 in Struts
Summary
by MITRE
When using a Spring AOP functionality to secure Struts actions it is possible to perform a DoS attack when user was properly authenticated. Solution is to upgrade to Apache Struts version 2.5.12 or 2.3.33.
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Analysis
by VulDB Data Team • 01/01/2021
The vulnerability identified as CVE-2017-9787 represents a critical denial of service weakness within Apache Struts frameworks that leverages Spring AOP security mechanisms. This flaw specifically manifests when authenticated users interact with Struts actions that are secured through Spring Aspect-Oriented Programming functionality, creating an exploitable condition that allows attackers to disrupt service availability. The vulnerability stems from improper handling of certain request parameters within the Struts framework when integrated with Spring AOP, enabling malicious actors to craft specific payloads that cause the application to consume excessive resources or enter unstable states.
The technical implementation of this vulnerability occurs through the interaction between Spring AOP's proxy mechanism and Struts action processing. When Spring AOP secures Struts actions, it creates dynamic proxies that intercept method calls to enforce security constraints. However, the vulnerability arises from inadequate validation of user input within this interception process, particularly when dealing with complex parameter structures. Attackers can exploit this by submitting carefully crafted requests that trigger recursive processing or excessive memory allocation within the Struts framework's action execution pipeline. The flaw operates at the application layer and can be classified under CWE-400 as an unspecified resource management error, specifically manifesting as a denial of service condition.
The operational impact of CVE-2017-9787 extends beyond simple service disruption to potentially affect business continuity and system availability. An attacker with valid authentication credentials can trigger resource exhaustion that causes the application server to become unresponsive or crash entirely, effectively rendering the service unavailable to legitimate users. This vulnerability is particularly dangerous because it requires only authenticated access, meaning that internal users or compromised accounts can exploit it to cause significant disruption. The attack can be executed with minimal resources and can be automated to create sustained denial of service conditions that are difficult to distinguish from legitimate traffic patterns.
Organizations affected by this vulnerability should immediately implement the recommended mitigation strategies, primarily focusing on upgrading to Apache Struts versions 2.5.12 or 2.3.33, which contain the necessary patches to address the underlying issue. Beyond the mandatory upgrade, security teams should implement additional protective measures including request rate limiting, input validation, and monitoring for unusual processing patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of proper security configuration management and the need for comprehensive testing when integrating different security frameworks like Spring AOP with web application frameworks such as Struts. This issue aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a classic example of how integrated security frameworks can introduce unexpected attack vectors when not properly coordinated. The vulnerability demonstrates the complexity of modern web application security where the interaction between multiple security layers can create new attack surfaces that are not immediately apparent during initial security assessments.