CVE-2016-0737 in Swift
Summary
by MITRE
OpenStack Object Storage (Swift) before 2.4.0 does not properly close client connections, which allows remote attackers to cause a denial of service (proxy-server resource consumption) via a series of interrupted requests to a Large Object URL.
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Analysis
by VulDB Data Team • 07/05/2018
The vulnerability identified as CVE-2016-0737 affects OpenStack Object Storage (Swift) versions prior to 2.4.0, representing a critical resource management flaw that can be exploited to execute denial of service attacks against proxy servers. This issue stems from the improper handling of client connections within the Swift storage system, specifically when processing requests related to Large Objects. The flaw creates a scenario where connection resources remain open and unreleased even when client interactions are interrupted or terminated prematurely, leading to gradual exhaustion of available system resources.
The technical implementation of this vulnerability occurs at the proxy-server level where Swift processes incoming requests for Large Object URLs. When clients establish connections to access large objects within the storage system but then disconnect abruptly or fail to complete their requests properly, the proxy server fails to clean up the associated connection resources. This connection leak manifests as persistent open file descriptors and memory allocations that accumulate over time, eventually consuming all available proxy-server resources. The vulnerability is particularly dangerous because it can be triggered through a series of interrupted requests rather than requiring a single malicious action, making it difficult to detect and mitigate.
From an operational impact perspective, this vulnerability creates significant risks for cloud infrastructure deployments relying on OpenStack Swift for object storage services. Attackers can systematically consume proxy-server resources by initiating multiple interrupted requests to Large Object URLs, leading to complete service unavailability for legitimate users. The resource consumption occurs gradually but persistently, making it challenging for administrators to identify the root cause of performance degradation. Organizations may experience complete service outages, increased latency for valid requests, and potential cascading failures that affect other components within the OpenStack ecosystem. This vulnerability directly impacts the availability and reliability of cloud storage services, undermining the core promise of cloud infrastructure.
The mitigation strategy for CVE-2016-0737 requires immediate deployment of OpenStack Swift version 2.4.0 or later, which includes proper connection cleanup mechanisms. System administrators should also implement connection timeout configurations and monitor proxy-server resource utilization to detect anomalous patterns. Network-level controls can be employed to limit the rate of requests from individual clients, helping to prevent exploitation of this vulnerability. Organizations should conduct thorough testing of updated systems to ensure compatibility and proper resource management. Additionally, implementing proper logging and monitoring solutions can help identify potential exploitation attempts and provide early warning of resource consumption anomalies. This vulnerability aligns with CWE-400, which categorizes resource exhaustion flaws, and maps to ATT&CK technique T1499.004 for network denial of service attacks, highlighting the importance of proper resource management in cloud infrastructure security.