CVE-2016-0738 in Swift
Summary
by MITRE
OpenStack Object Storage (Swift) before 2.3.1 (Kilo), 2.4.x, and 2.5.x before 2.5.1 (Liberty) do not properly close server 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 • 07/06/2022
The vulnerability identified as CVE-2016-0738 affects OpenStack Object Storage (Swift) systems operating in specific version ranges including releases prior to 2.3.1 in the Kilo series, all 2.4.x releases, and versions before 2.5.1 in the Liberty series. This flaw represents a critical resource management issue that directly impacts the proxy-server component of the Swift architecture. The vulnerability stems from improper handling of server connections within the proxy-server process, specifically failing to properly close network connections when requests are interrupted or terminated prematurely.
The technical implementation of this vulnerability involves the proxy-server maintaining active connection handles even when client requests are abruptly terminated or interrupted. When attackers send a series of requests to Large Object URLs within Swift, they can exploit the connection management flaw by interrupting these requests before normal completion. This action causes the proxy-server to retain connection resources indefinitely, leading to progressive resource exhaustion. The flaw operates at the network protocol level where connection state management fails to account for interrupted request cycles, creating a memory and file descriptor leak scenario within the server process.
The operational impact of this vulnerability manifests as a sustained denial of service condition that gradually consumes proxy-server resources until system stability is compromised. Attackers can maintain persistent resource consumption by repeatedly sending interrupted requests to Large Object URLs, effectively creating a resource starvation attack against the Swift storage infrastructure. The vulnerability particularly affects systems handling large objects since the connection management issues are more pronounced when dealing with extended data transfer operations. This type of attack can render storage services unavailable to legitimate users while potentially causing system crashes or requiring manual intervention to restore service.
This vulnerability maps to CWE-400, which specifically addresses "Uncontrolled Resource Consumption" or "Resource Leak" conditions in software systems. The flaw also aligns with ATT&CK technique T1499.004, "Application Exhaustion Flood," which describes methods of consuming system resources to cause service disruption. The improper connection handling represents a classic resource management vulnerability where the system fails to properly clean up allocated resources during abnormal termination conditions. Organizations should implement immediate patching strategies to address the specific version ranges mentioned in the vulnerability description, ensuring that all Swift deployments are updated to versions containing proper connection closure mechanisms.
The remediation approach requires deployment of patched versions of OpenStack Swift that include proper connection management logic to ensure all network handles are correctly closed regardless of request termination status. System administrators should also implement monitoring solutions to detect unusual connection patterns that may indicate exploitation attempts. Additional defensive measures include configuring connection timeouts, implementing rate limiting for Large Object access, and establishing resource quotas to prevent single entities from consuming excessive proxy-server resources. The vulnerability highlights the importance of proper resource lifecycle management in distributed storage systems where connection handling directly impacts service availability and system stability.