CVE-2017-8761 in Swift
Summary
by MITRE • 06/02/2021
In OpenStack Swift through 2.10.1, 2.11.0 through 2.13.0, and 2.14.0, the proxy-server logs full tempurl paths, potentially leaking reusable tempurl signatures to anyone with read access to these logs. All Swift deployments using the tempurl middleware are affected.
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Analysis
by VulDB Data Team • 06/05/2021
The vulnerability described in CVE-2017-8761 represents a critical information disclosure flaw within OpenStack Swift's proxy-server component that has significant implications for cloud storage security. This vulnerability affects multiple versions of the Swift object storage system, specifically those ranging from version 2.10.1 through 2.13.0 and including version 2.14.0, while also encompassing versions 2.11.0 through 2.13.0. The flaw stems from improper logging practices where the system records complete temporary URL paths that contain sensitive signature parameters, creating a substantial security risk for organizations relying on Swift's tempurl middleware functionality.
The technical root cause of this vulnerability lies in the proxy-server's logging mechanism which indiscriminately captures and stores full tempurl paths including their cryptographic signatures without proper sanitization or obfuscation. When Swift deployments utilize the tempurl middleware, temporary URLs are generated to provide time-limited access to objects within the storage system. These URLs contain signature parameters that are critical for authentication and authorization purposes, and they become invalid after a specified time period. However, the proxy-server's logging behavior inadvertently exposes these complete URLs, including their signature components, to any individual who gains read access to the system's log files. This represents a direct violation of information security principles and creates a potential attack vector for unauthorized access to protected resources.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally undermines the security model of temporary access controls within OpenStack Swift. Attackers who gain access to system logs can extract reusable tempurl signatures that may grant them access to sensitive data, potentially leading to unauthorized data reading, modification, or deletion operations. The vulnerability affects all Swift deployments using the tempurl middleware, making it a widespread concern across the OpenStack ecosystem. Organizations utilizing Swift for cloud storage services face significant risks including data breaches, compliance violations, and potential regulatory penalties when such sensitive signature information is exposed through log files. The impact is particularly severe because tempurl signatures are designed to be time-limited and secure, yet this flaw renders them potentially reusable by unauthorized parties.
From a cybersecurity perspective, this vulnerability aligns with CWE-209, which addresses information exposure through log data, and demonstrates characteristics consistent with ATT&CK technique T1070.001 related to indicator removal on host. The flaw represents a failure in proper input validation and output sanitization within the logging subsystem, where sensitive data is not adequately protected during the logging process. Organizations should implement immediate mitigations including log file access controls, signature parameter obfuscation in logs, and regular log auditing procedures. The recommended approach involves updating to patched versions of Swift, implementing proper log sanitization measures, and establishing monitoring protocols to detect unauthorized access to log files. Additionally, security teams should conduct comprehensive vulnerability assessments to identify any other systems that may be exposing similar information through logging mechanisms, as this represents a systemic security weakness that could affect similar components within cloud infrastructure deployments.