CVE-2018-8028 in Sentry
Summary
by MITRE
An authenticated user can execute ALTER TABLE EXCHANGE PARTITIONS without being authorized by Apache Sentry before 2.0.1. This can allow an attacker unauthorized access to the partitioned data of a Sentry protected table and can allow an attacker to remove data from a Sentry protected table.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/17/2020
The vulnerability described in CVE-2018-8028 represents a critical authorization bypass flaw within Apache Sentry, a security framework designed to provide fine-grained access control for Apache Hadoop ecosystems. This issue affects versions prior to 2.0.1 and specifically targets the authorization mechanisms governing partitioned table operations within database systems that utilize Sentry for access control. The flaw resides in the permission validation logic that governs ALTER TABLE EXCHANGE PARTITIONS commands, which are commonly used to swap partitions between tables in data warehousing environments. When an authenticated user exploits this vulnerability, they can manipulate partitioned data without proper authorization, effectively circumventing the security controls that Sentry is designed to enforce. This represents a fundamental breakdown in the principle of least privilege that security frameworks like Sentry are intended to maintain.
The technical implementation of this vulnerability stems from insufficient authorization checks during partition exchange operations within the Sentry authorization system. When users execute ALTER TABLE EXCHANGE PARTITIONS commands, the system should verify that the user possesses appropriate permissions on both source and target tables before allowing the operation to proceed. However, in affected versions, Sentry fails to properly validate these permissions, allowing authenticated users to perform partition exchanges regardless of their actual access rights to the underlying data. This flaw particularly impacts partitioned tables where data is organized across multiple partitions for performance and management reasons. The vulnerability manifests when users can exchange partitions between tables without proper authorization, potentially allowing them to access data they should not be permitted to view or modify. The underlying mechanism involves the authorization service not properly evaluating access control lists for partition-level operations, creating a gap in the security model that attackers can exploit.
The operational impact of this vulnerability extends beyond simple unauthorized data access, creating significant risks for data integrity and confidentiality within organizations using Sentry-protected systems. Attackers who successfully exploit this vulnerability can not only access partitioned data they should not be authorized to view but can also potentially remove or manipulate data within protected tables through partition exchange operations. This capability enables a range of malicious activities including data exfiltration, data corruption, and unauthorized data removal. The vulnerability particularly affects data warehousing and analytics environments where partitioned tables are commonly used for performance optimization and data management. Organizations relying on Sentry for access control may experience unauthorized data exposure, potentially leading to compliance violations, data breaches, and significant operational disruptions. The impact is amplified in environments where sensitive data is partitioned across multiple tables, as attackers can leverage this vulnerability to access cross-table data that should remain protected.
Organizations should implement immediate mitigations including upgrading to Apache Sentry version 2.0.1 or later, which contains the necessary fixes for this authorization bypass vulnerability. The upgrade process should include thorough testing to ensure compatibility with existing applications and workflows that utilize partition exchange operations. Additionally, administrators should review existing access control policies and implement additional monitoring for partition-related operations to detect potential unauthorized activities. Security teams should consider implementing network-level controls and logging mechanisms that track ALTER TABLE EXCHANGE PARTITIONS commands, as these operations are often used as attack vectors in data manipulation scenarios. The vulnerability aligns with CWE-284, which addresses improper access control, and represents a specific instance of insufficient authorization checks in database management systems. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation and data manipulation techniques, as attackers can leverage it to gain unauthorized access to protected data and potentially remove or alter information within Sentry-protected tables. Organizations should also consider implementing principle of least privilege enforcement, ensuring that users have minimal necessary permissions for their operational requirements while maintaining system functionality and security controls.