CVE-2020-17533 in Accumulo
Summary
by MITRE • 12/29/2020
Apache Accumulo versions 1.5.0 through 1.10.0 and version 2.0.0 do not properly check the return value of some policy enforcement functions before permitting an authenticated user to perform certain administrative operations. Specifically, the return values of the 'canFlush' and 'canPerformSystemActions' security functions are not checked in some instances, therefore allowing an authenticated user with insufficient permissions to perform the following actions: flushing a table, shutting down Accumulo or an individual tablet server, and setting or removing system-wide Accumulo configuration properties.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/29/2020
This vulnerability represents a critical authorization bypass flaw in Apache Accumulo that undermines the system's security model through improper validation of policy enforcement functions. The issue affects versions ranging from 1.5.0 through 1.10.0 and specifically 2.0.0, creating a persistent security weakness that allows authenticated users to escalate their privileges without proper authorization. The vulnerability stems from the failure to validate return values from essential security functions, particularly those governing table flushing operations and system-wide administrative actions.
The technical flaw manifests in two primary security functions: 'canFlush' and 'canPerformSystemActions'. These functions are designed to enforce access controls and determine whether authenticated users possess sufficient privileges to execute sensitive operations. However, in certain code paths, the return values from these functions are ignored, allowing attackers to bypass authorization checks entirely. This creates a scenario where users who should not have permission to perform administrative tasks can nevertheless execute them, fundamentally compromising the principle of least privilege that underpins secure system design.
The operational impact of this vulnerability is severe and multifaceted, as it enables authenticated users to perform critical administrative operations that should be restricted to authorized administrators only. Users can flush tables, which disrupts data consistency and availability while potentially exposing sensitive information through temporary data states. Additionally, the ability to shut down Accumulo systems or individual tablet servers creates opportunities for denial of service attacks that can severely impact business operations. The most concerning aspect involves configuration management permissions, where unauthorized users can modify system-wide properties that govern security policies, performance characteristics, and operational behavior.
This vulnerability maps directly to CWE-284 Access Control Bypass, which specifically addresses situations where insufficient checks are performed on access control mechanisms, allowing unauthorized entities to perform privileged operations. The flaw also aligns with ATT&CK technique T1078 Valid Accounts, as it leverages existing authenticated user sessions to escalate privileges rather than requiring additional authentication methods or exploitation of separate vulnerabilities. From a security perspective, this represents a failure in the principle of defense in depth, where multiple layers of security controls are bypassed through a single point of failure in the authorization mechanism.
Organizations utilizing affected Accumulo versions should immediately implement mitigations including upgrading to patched versions that properly validate return values from security functions and implementing additional monitoring controls to detect unauthorized administrative activities. Network segmentation and least privilege access controls should be enforced to limit exposure, while regular security audits should verify proper authorization enforcement. The vulnerability demonstrates the critical importance of thorough code review processes specifically focused on security-critical functions and the necessity of comprehensive testing for authorization checks in distributed database systems where administrative privileges can have far-reaching consequences across entire data platforms.