CVE-2014-6259 in Zenoss
Summary
by MITRE
Zenoss Core through 5 Beta 3 does not properly detect recursion during entity expansion, which allows remote attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, aka ZEN-15414, a similar issue to CVE-2003-1564.
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Analysis
by VulDB Data Team • 09/11/2024
The vulnerability identified as CVE-2014-6259 affects Zenoss Core versions through 5 Beta 3 and represents a classic example of a denial of service attack leveraging XML entity expansion recursion. This flaw resides in the XML parsing mechanism of the Zenoss monitoring platform, which is designed to process and analyze complex data structures from various network devices and systems. The vulnerability specifically manifests when the system encounters crafted XML documents containing deeply nested entity references that trigger recursive expansion without proper safeguards. This issue is categorized under CWE-400 as an unchecked resource consumption problem, where the system fails to implement adequate recursion detection and limit mechanisms during XML parsing operations. The vulnerability operates at the application layer and can be exploited remotely, making it particularly dangerous in networked environments where Zenoss Core systems process untrusted data from multiple sources.
The technical implementation of this vulnerability stems from the XML parser's inability to detect and prevent infinite recursion during entity expansion processes. When a maliciously crafted XML document contains numerous nested entity references, the parser attempts to recursively expand each entity reference, leading to exponential growth in processing requirements. This recursive expansion consumes increasing amounts of memory and CPU resources as the parser traverses deeper levels of nested entities. The flaw is particularly insidious because it can be triggered through legitimate XML processing pathways, meaning that even trusted XML sources could potentially be exploited if they contain maliciously crafted content. The vulnerability demonstrates characteristics of CWE-611, which relates to improper restriction of XML external entity references, though it specifically focuses on the recursive expansion aspect rather than external entity access. This issue operates within the broader context of XML parsing security concerns and has been previously documented in similar vulnerabilities such as CVE-2003-1564, which highlighted the same class of problems in other XML processing libraries.
The operational impact of CVE-2014-6259 is significant for organizations relying on Zenoss Core for network monitoring and system management. Attackers can exploit this vulnerability to consume excessive system resources, potentially leading to complete system unavailability and denial of service for legitimate monitoring operations. The memory and CPU exhaustion occurs gradually but can escalate rapidly depending on the depth and complexity of the nested entity references in the crafted XML document. This makes the vulnerability particularly dangerous in production environments where Zenoss Core systems are continuously processing monitoring data from network devices. The impact extends beyond simple service disruption as it can affect the entire monitoring infrastructure, potentially masking real security incidents or system failures that the monitoring platform was designed to detect. Organizations may experience cascading failures where the denial of service affects not only the Zenoss Core system but also dependent services and applications that rely on the monitoring data for operational decisions.
Mitigation strategies for CVE-2014-6259 should focus on implementing proper XML parsing restrictions and resource limits within the Zenoss Core environment. Organizations should upgrade to patched versions of Zenoss Core that implement recursion detection mechanisms and set appropriate limits on entity expansion depth and total entity count. The implementation should include configuring XML parsers to enforce maximum nesting levels and prevent recursive entity expansion beyond predetermined thresholds. Network segmentation and input validation measures can help reduce the attack surface by limiting the sources of XML data that can reach the vulnerable parsing components. Security controls should also include monitoring for unusual resource consumption patterns that might indicate exploitation attempts. From an ATT&CK perspective, this vulnerability aligns with techniques involving resource exhaustion and denial of service, specifically targeting the availability aspect of the CIA triad. Organizations should also consider implementing web application firewalls or XML gateways that can filter and sanitize incoming XML content before it reaches the vulnerable Zenoss Core components. Regular security assessments and vulnerability scanning should include checks for proper XML parsing configurations to ensure that recursion detection mechanisms are properly implemented and functioning as intended.