CVE-2013-4202 in Compute
Summary
by MITRE
The (1) backup (api/contrib/backups.py) and (2) volume transfer (contrib/volume_transfer.py) APIs in OpenStack Cinder Grizzly 2013.1.3 and earlier allows remote attackers to cause a denial of service (resource consumption and crash) via an XML Entity Expansion (XEE) attack. NOTE: this issue is due to an incomplete fix for CVE-2013-1664.
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Analysis
by VulDB Data Team • 01/07/2022
The vulnerability described in CVE-2013-4202 represents a critical denial of service weakness affecting OpenStack Cinder Grizzly 2013.1.3 and earlier versions. This issue specifically targets two core API components within the Cinder storage service: the backup functionality located at api/contrib/backups.py and the volume transfer functionality found in contrib/volume_transfer.py. The vulnerability stems from insufficient protection against XML Entity Expansion attacks, which constitute a well-known class of resource exhaustion threats that have been documented in various security frameworks including CWE-611. The flaw manifests when the affected APIs process XML input without proper safeguards against recursive entity expansion, allowing malicious actors to craft specially formatted requests that can consume excessive system resources.
The technical implementation of this vulnerability operates through the exploitation of XML parsing mechanisms that do not adequately restrict entity expansion limits. When the backup and volume transfer APIs receive XML data containing maliciously crafted entity references, they recursively expand these entities without proper boundary checks, leading to exponential resource consumption patterns. This behavior directly aligns with the ATT&CK technique T1499.004 for resource exhaustion attacks, where adversaries leverage XML parsing vulnerabilities to consume system memory and processing power. The incomplete fix for the previously disclosed CVE-2013-1664 demonstrates a pattern of security remediation gaps that leave systems vulnerable to similar attack vectors. The attack surface is particularly concerning as these APIs are part of the core storage management functionality in OpenStack environments, making them attractive targets for attackers seeking to disrupt cloud storage services.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire storage infrastructure of affected OpenStack deployments. When exploited, the XML Entity Expansion attack causes the targeted APIs to consume excessive memory and CPU resources, leading to application crashes and denial of service conditions that can affect multiple storage operations simultaneously. This vulnerability particularly threatens production cloud environments where Cinder services handle critical storage operations for numerous virtual machines and applications. The resource consumption patterns associated with XEE attacks can cause cascading failures throughout the cloud infrastructure, as affected processes may consume all available system resources and prevent legitimate operations from completing successfully. Organizations relying on these storage services face significant operational risks including data access interruptions, service degradation, and potential loss of storage capacity availability.
Mitigation strategies for CVE-2013-4202 require immediate implementation of XML parsing restrictions and input validation controls within the affected API endpoints. Security administrators should implement proper entity expansion limits in XML parsers, typically setting maximum entity expansion depths and total character limits to prevent recursive expansion behaviors. The recommended approach includes deploying XML security configurations that disable external entity resolution and restrict entity expansion to reasonable limits, which directly addresses the CWE-611 category of XML external entity vulnerabilities. Organizations should also consider implementing network-level controls to monitor and restrict XML traffic to these specific API endpoints, particularly in environments where the vulnerable versions remain operational. The most effective long-term solution involves upgrading to patched versions of OpenStack Cinder that properly address both CVE-2013-4202 and its predecessor CVE-2013-1664, ensuring complete remediation of the XML parsing vulnerabilities. Additionally, implementing comprehensive logging and monitoring of API activity can help detect potential exploitation attempts and provide early warning of active attacks against these vulnerable endpoints.