CVE-2021-40331: Apache Ranger Privilege Escalation Flaw

CVE-2021-40331 Overview

An Incorrect Permission Assignment for Critical Resource vulnerability (CWE-732) was discovered in the Apache Ranger Hive Plugin. This security flaw allows any user with SELECT privilege on a database to alter the ownership of tables in Hive when the Apache Ranger Hive Plugin is enabled. This privilege escalation vulnerability could allow unauthorized users to gain control over critical database resources they should not be able to modify.

Critical Impact

Users with minimal SELECT privileges can escalate their access by taking ownership of Hive tables, potentially gaining full control over sensitive data and database resources.

Affected Products

• Apache Ranger Hive Plugin versions 2.0.0 through 2.3.0

Discovery Timeline

• 2023-05-05 - CVE-2021-40331 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-40331

Vulnerability Analysis

This vulnerability stems from an incorrect permission assignment mechanism within the Apache Ranger Hive Plugin. The plugin fails to properly validate whether a user possesses sufficient privileges to perform ownership modification operations on Hive tables. As a result, users who only have SELECT privileges—typically a read-only access level—can exploit this flaw to alter table ownership.

The attack is network-accessible and requires low complexity to execute. An attacker needs only low-level privileges (SELECT access) to exploit this vulnerability. The impact is significant, affecting both confidentiality and integrity of the Hive environment, as the attacker can gain unauthorized access to data and modify critical database configurations.

Root Cause

The root cause lies in the permission validation logic of the Apache Ranger Hive Plugin. The plugin does not adequately enforce access control checks when processing table ownership modification requests. The authorization layer fails to verify that the requesting user has administrative privileges before allowing ownership changes, instead only checking for the presence of SELECT privileges.

This is classified as CWE-732: Incorrect Permission Assignment for Critical Resource, where the software incorrectly assigns permissions for a resource in a way that exposes the resource to unintended actors.

Attack Vector

The attack vector for CVE-2021-40331 is network-based. An authenticated attacker with basic SELECT privileges on a Hive database can remotely exploit this vulnerability to change table ownership. The attack does not require any user interaction and can be executed directly through standard Hive operations.

The exploitation scenario involves:

1. An attacker authenticates to the Hive environment with a low-privileged account that has SELECT access to a database
2. With Apache Ranger Hive Plugin enabled (versions 2.0.0 through 2.3.0), the attacker issues a table ownership modification command
3. Due to insufficient permission validation, the command succeeds despite the attacker lacking administrative privileges
4. The attacker gains ownership of the table, enabling further malicious activities including data exfiltration or modification

Detection Methods for CVE-2021-40331

Indicators of Compromise

• Unexpected changes to Hive table ownership records
• ALTER TABLE ownership commands executed by users with only SELECT privileges
• Audit logs showing privilege escalation patterns in Hive metadata operations
• Unauthorized access to sensitive tables following ownership changes

Detection Strategies

• Monitor Apache Ranger audit logs for table ownership modification operations performed by non-administrative users
• Implement alerts for ALTER TABLE commands that change ownership originating from accounts with limited privileges
• Review Hive metastore logs for anomalous ownership transfer patterns
• Correlate user privilege levels with table modification activities to identify privilege escalation attempts

Monitoring Recommendations

• Enable comprehensive audit logging in Apache Ranger for all policy enforcement decisions
• Configure real-time alerting for ownership changes on critical Hive tables
• Implement periodic reviews of table ownership against expected configurations
• Deploy SIEM rules to detect patterns consistent with privilege escalation in Hive environments

How to Mitigate CVE-2021-40331

Immediate Actions Required

• Upgrade Apache Ranger to version 2.4.0 or later immediately
• Review all recent table ownership changes in affected Hive environments for unauthorized modifications
• Audit user privileges to ensure SELECT-only users cannot perform administrative operations
• Temporarily restrict access to sensitive Hive tables until the upgrade is complete

Patch Information

Apache has addressed this vulnerability in Apache Ranger version 2.4.0. Users running Apache Ranger Hive Plugin versions 2.0.0 through 2.3.0 should upgrade to version 2.4.0 or later. The security advisory is available on the Apache Mailing List Thread.

Workarounds

• If immediate upgrade is not possible, implement additional access controls at the network layer to restrict Hive access to trusted users only
• Review and restrict SELECT privileges on sensitive databases to minimize the attack surface
• Implement additional monitoring and alerting for table ownership changes as an interim control
• Consider disabling the Apache Ranger Hive Plugin temporarily if the risk is deemed critical and upgrade cannot be performed immediately

# Verify Apache Ranger version
ranger-admin version

# Check for affected Hive Plugin installations
ls -la /usr/hdp/current/ranger-hive-plugin/

# Review current table ownership in Hive
hive -e "DESCRIBE FORMATTED your_database.your_table" | grep Owner