CVE-2018-1327 in Struts REST Plugin
Summary
by MITRE
The Apache Struts REST Plugin is using XStream library which is vulnerable and allow perform a DoS attack when using a malicious request with specially crafted XML payload. Upgrade to the Apache Struts version 2.5.16 and switch to an optional Jackson XML handler as described here http://struts.apache.org/plugins/rest/#custom-contenttypehandlers. Another option is to implement a custom XML handler based on the Jackson XML handler from the Apache Struts 2.5.16.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 02/06/2021
The vulnerability identified as CVE-2018-1327 represents a critical denial of service weakness within the Apache Struts framework that specifically affects the REST plugin implementation. This flaw manifests through the improper handling of XML payloads within the XStream library integration, creating an exploitable condition where malicious actors can craft specially formatted requests designed to overwhelm system resources and cause service disruption. The issue stems from the default configuration of the REST plugin that relies on XStream for XML processing, making it susceptible to resource exhaustion attacks that can effectively render applications unavailable to legitimate users. Organizations running affected Apache Struts versions face significant operational risks as this vulnerability can be exploited without authentication and requires minimal technical expertise to implement.
The technical implementation of this vulnerability involves the XStream library's deserialization process which lacks proper input validation and resource limiting mechanisms when processing malformed XML data. When the REST plugin receives a crafted XML payload, the XStream parser attempts to deserialize the content in a manner that consumes excessive computational resources including memory allocation and processing cycles. This behavior aligns with CWE-400 which categorizes improper resource exhaustion vulnerabilities, specifically targeting denial of service conditions through resource consumption attacks. The vulnerability operates at the application layer and can be classified under ATT&CK technique T1499.004 which describes network denial of service attacks targeting application availability.
The operational impact of CVE-2018-1327 extends beyond simple service disruption to encompass potential business continuity issues and increased operational overhead for security teams. Organizations may experience cascading effects where a single exploited instance can cause widespread application unavailability across dependent systems, particularly in environments where multiple applications share common Struts frameworks. The vulnerability's exploitability is enhanced by the fact that it requires no authentication and can be executed through standard HTTP requests, making it particularly dangerous in publicly accessible applications. Security operations centers must implement immediate monitoring and response procedures to detect and mitigate exploitation attempts while simultaneously planning the necessary software upgrades.
Mitigation strategies for this vulnerability center on software version upgrades to Apache Struts 2.5.16 or later versions which include patched XStream integration and improved resource handling mechanisms. The recommended approach involves transitioning from the vulnerable XStream library to the optional Jackson XML handler as outlined in the official Apache Struts documentation, providing a more robust and secure XML processing implementation. Organizations should also consider implementing custom XML handlers based on the Jackson framework's approach to ensure compatibility with existing application requirements while maintaining security posture. Additional protective measures include implementing network-level rate limiting, input validation at the application firewall level, and regular security scanning to identify potentially affected components within the application stack. The vulnerability's resolution requires careful coordination between development teams and security operations to ensure proper implementation without disrupting existing application functionality while establishing proper security controls to prevent future similar issues.