CVE-2021-35576 Overview
CVE-2021-35576 is a vulnerability in the Oracle Database Enterprise Edition Unified Audit component of Oracle Database Server. This easily exploitable vulnerability allows a high privileged attacker with Local Logon privilege and network access via Oracle Net to compromise the Unified Audit component. Successful exploitation can result in unauthorized update, insert, or delete access to some of the Oracle Database Enterprise Edition Unified Audit accessible data, potentially allowing attackers to bypass audit policies and manipulate audit records.
Critical Impact
A privileged attacker can bypass unified audit policies, potentially enabling unauthorized data modifications while evading detection through audit log manipulation.
Affected Products
- Oracle Database Server 12.1.0.2 Enterprise Edition
- Oracle Database Server 12.2.0.1 Enterprise Edition
- Oracle Database Server 19c Enterprise Edition
Discovery Timeline
- October 20, 2021 - CVE-2021-35576 published to NVD
- November 21, 2024 - Last updated in NVD database
Technical Details for CVE-2021-35576
Vulnerability Analysis
This vulnerability affects the Unified Audit component within Oracle Database Enterprise Edition, which is designed to provide comprehensive auditing capabilities for database activities. The flaw allows privileged users with Local Logon rights to bypass audit policies, potentially enabling them to perform unauthorized data modifications without proper audit trail generation.
The vulnerability requires network access via Oracle Net, which is Oracle's networking layer for database connectivity. While the attack requires high privileges, the low attack complexity means that once an attacker has the necessary access level, exploitation is straightforward.
The integrity impact is limited to the Unified Audit accessible data, meaning attackers can manipulate audit-related information but cannot directly access or modify other database contents through this vulnerability alone. However, the ability to bypass audit policies represents a significant security concern as it undermines the database's accountability and compliance mechanisms.
Root Cause
The vulnerability stems from improper access control within the Unified Audit component that fails to adequately restrict privileged users from bypassing audit policy enforcement. This allows users with elevated privileges to manipulate audit data or circumvent audit logging for specific operations, undermining the integrity of the audit trail.
Attack Vector
The attack is conducted over the network via Oracle Net, requiring the attacker to have high privileges and Local Logon capability on the target Oracle Database Server. The attacker leverages their privileged position to exploit weaknesses in the Unified Audit component's access controls.
The vulnerability does not require user interaction to exploit, making it potentially dangerous in environments where privileged accounts may be compromised or where insider threats exist. The attack allows the adversary to modify or delete audit data, which could be used to cover tracks after performing other malicious activities on the database.
Technical details regarding the specific bypass mechanism can be found in the Database Security Ninja Analysis and the Packet Storm Oracle Policy Bypass advisory.
Detection Methods for CVE-2021-35576
Indicators of Compromise
- Unexpected modifications or deletions within the UNIFIED_AUDIT_TRAIL view
- Gaps or inconsistencies in audit log timestamps that suggest record manipulation
- Database sessions from privileged accounts accessing audit-related system tables during unusual hours
Detection Strategies
- Monitor access patterns to the Unified Audit system tables and views for anomalous privileged user activity
- Implement database activity monitoring (DAM) solutions to track all privileged operations independent of native Oracle auditing
- Cross-reference Oracle native audit logs with external logging systems to identify discrepancies
Monitoring Recommendations
- Enable supplemental logging to capture detailed audit trail information in external SIEM systems
- Configure alerts for any DML operations targeting audit-related database objects
- Review privileged account activity regularly, focusing on users with Local Logon privileges
How to Mitigate CVE-2021-35576
Immediate Actions Required
- Apply the October 2021 Critical Patch Update from Oracle immediately
- Review and restrict accounts with high privileges and Local Logon access to only those absolutely required
- Implement network segmentation to limit Oracle Net access from untrusted network segments
- Enable additional monitoring on privileged database sessions
Patch Information
Oracle has released a security patch addressing this vulnerability in the October 2021 Critical Patch Update (CPU). Organizations running affected versions (12.1.0.2, 12.2.0.1, or 19c) of Oracle Database Server Enterprise Edition should apply this patch as soon as possible.
Workarounds
- Implement defense-in-depth by configuring external audit log collection that operates independently of the Unified Audit component
- Restrict network access to Oracle Net ports using firewall rules and access control lists
- Enforce principle of least privilege by auditing and reducing the number of accounts with high privileges
# Example: Restrict Oracle Net listener access using Oracle Net Manager or sqlnet.ora
# Add to sqlnet.ora to limit connections to specific IP ranges
TCP.VALIDNODE_CHECKING = YES
TCP.INVITED_NODES = (192.168.1.0/24, 10.0.0.0/8)
TCP.EXCLUDED_NODES = (0.0.0.0/0)
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
