CVE-2014-1868 in Restlet
Summary
by MITRE
Restlet Framework 2.1.x before 2.1.7 and 2.x.x before 2.2 RC1, when using XMLRepresentation or XML serializers, allows attackers to cause a denial of service via an XML Entity Expansion (XEE) attack.
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Analysis
by VulDB Data Team • 03/13/2019
The vulnerability identified as CVE-2014-1868 represents a critical security flaw in the Restlet Framework versions prior to 2.1.7 and 2.2 RC1. This issue specifically affects applications that utilize XMLRepresentation or XML serializers within the framework, creating a pathway for malicious actors to exploit XML Entity Expansion attacks. The vulnerability stems from insufficient input validation and processing of XML documents, allowing attackers to craft specially malformed XML content that can trigger excessive resource consumption during parsing operations.
The technical implementation of this vulnerability involves the framework's XML processing mechanisms failing to properly restrict the expansion of XML entities during document parsing. When an XML document containing external entity declarations or recursive entity references is processed, the Restlet Framework does not adequately limit the expansion process, leading to exponential resource consumption patterns. This behavior aligns with the common characteristics of XML External Entity attacks as classified under CWE-611, which specifically addresses improper restriction of XML external entity references. The vulnerability enables attackers to craft XML payloads that cause the application to consume excessive CPU cycles and memory resources, ultimately leading to denial of service conditions.
From an operational impact perspective, this vulnerability poses significant risks to applications relying on Restlet Framework for XML processing capabilities. Attackers can exploit this weakness to consume system resources at rates that can overwhelm server capacity, effectively rendering applications unavailable to legitimate users. The attack can be executed through various means including direct HTTP requests containing malicious XML content, file uploads with XML attachments, or any interaction that processes XML data through the vulnerable framework components. The impact extends beyond simple service disruption as the resource exhaustion can affect system stability and potentially impact other applications running on the same infrastructure.
The mitigation strategies for CVE-2014-1868 primarily focus on updating the Restlet Framework to versions that properly address XML entity expansion vulnerabilities. Organizations should immediately upgrade to Restlet Framework 2.1.7 or 2.2 RC1 and later versions where the XML processing components have been hardened against entity expansion attacks. Additionally, administrators should implement XML parser configurations that disable external entity resolution andDTD processing, which aligns with recommended practices from the Open Web Application Security Project. The ATT&CK framework categorizes this vulnerability under the 'Resource Exhaustion' technique, specifically targeting application-level resource consumption through malformed input processing. Security teams should also consider implementing network-level controls and monitoring for unusual XML processing patterns that could indicate exploitation attempts, as well as establishing proper input validation and sanitization measures for all XML content entering the system.