CVE-2015-1856 in Object Storage
Summary
by MITRE
OpenStack Object Storage (Swift) before 2.3.0, when allow_version is configured, allows remote authenticated users to delete the latest version of an object by leveraging listing access to the x-versions-location container.
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Analysis
by VulDB Data Team • 05/09/2022
The vulnerability identified as CVE-2015-1856 affects OpenStack Object Storage (Swift) versions prior to 2.3.0 and represents a significant access control flaw that enables authenticated attackers to manipulate object versioning mechanisms. This issue specifically arises when the allow_version configuration parameter is enabled, creating a path for unauthorized deletion of the most recent object versions within versioned containers. The vulnerability stems from improper access control validation during version management operations, particularly when dealing with x-versions-location containers that store historical object versions.
The technical flaw manifests through a privilege escalation vector that leverages existing listing permissions within the storage system. When an authenticated user possesses listing access to a container designated as x-versions-location, they can exploit this access to identify and subsequently delete the latest version of objects stored within versioned containers. This occurs because the system fails to properly validate whether the requesting user has the appropriate deletion permissions for the specific object version they intend to remove. The vulnerability operates at the application layer and requires only authentication credentials, making it particularly dangerous in multi-tenant environments where users may have varying levels of access rights.
The operational impact of this vulnerability extends beyond simple data loss, as it compromises the integrity and availability of versioned object storage systems. Attackers can effectively bypass normal versioning controls and remove the most recent versions of files, potentially leading to permanent data loss or disruption of business operations that depend on versioned storage. This flaw is particularly concerning in cloud environments where organizations rely on versioning for data recovery and compliance purposes. The vulnerability affects the core object storage functionality and can be exploited across multiple objects within affected containers, potentially causing widespread disruption to storage services and undermining the trust in the versioning system's security controls.
Mitigation strategies for CVE-2015-1856 should focus on immediate patching of affected OpenStack Swift installations to version 2.3.0 or later, which contains the necessary security fixes. Organizations should also implement strict access control policies that limit listing permissions for x-versions-location containers and ensure that users with listing access cannot perform destructive operations without proper authorization. The principle of least privilege should be enforced, where users are granted only the minimum permissions required for their operational tasks. Additionally, regular security audits of storage configurations should be conducted to identify and remediate similar access control issues. This vulnerability aligns with CWE-284, which addresses improper access control, and relates to ATT&CK technique T1566, focusing on credential access through privilege escalation. Organizations should also consider implementing monitoring and alerting mechanisms to detect unusual deletion patterns in versioned containers, providing additional layers of defense against similar exploitation vectors.