CVE-2021-2337: Oracle Database Privilege Escalation Flaw

CVE-2021-2337 Overview

CVE-2021-2337 is a high-severity vulnerability affecting the Oracle XML DB component of Oracle Database Server. This easily exploitable flaw allows a high-privileged attacker with Create Any Procedure and Create Public Synonym privileges to compromise the Oracle XML DB component via network access through Oracle Net. Successful exploitation can result in a complete takeover of Oracle XML DB, impacting confidentiality, integrity, and availability.

Critical Impact

An authenticated attacker with elevated privileges can achieve full compromise of Oracle XML DB, potentially gaining unauthorized access to sensitive data, modifying database content, and disrupting database availability.

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

• 2021-07-21 - CVE CVE-2021-2337 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-2337

Vulnerability Analysis

This vulnerability exists within the Oracle XML DB component, which provides native XML storage and retrieval capabilities within the Oracle Database. The flaw enables privilege escalation and component takeover when exploited by an attacker who already possesses elevated database privileges.

The attack requires network access via Oracle Net, Oracle's proprietary networking protocol used for client-to-server and server-to-server communication. While the vulnerability requires high privileges to exploit, the low attack complexity means that once an attacker has the necessary Create Any Procedure and Create Public Synonym privileges, exploitation is straightforward.

The complete compromise of Oracle XML DB can lead to unauthorized access to XML-stored data, manipulation of database content through the XML DB interface, and potential disruption of services relying on XML processing capabilities.

Root Cause

While Oracle has not disclosed specific technical details about the root cause (classified as NVD-CWE-noinfo), the vulnerability is associated with privilege handling within the Oracle XML DB component. The requirement for Create Any Procedure and Create Public Synonym privileges suggests the vulnerability may involve improper validation of privileged operations or inadequate access controls on certain XML DB functions that can be leveraged to escalate privileges or bypass security boundaries.

Attack Vector

The attack vector is network-based, requiring the attacker to have authenticated access to the Oracle Database with specific elevated privileges. The exploitation path involves:

1. An attacker obtains credentials for a database account with Create Any Procedure and Create Public Synonym privileges
2. The attacker connects to the Oracle Database via Oracle Net protocol
3. Through crafted operations targeting the Oracle XML DB component, the attacker achieves a takeover of the component
4. This grants unauthorized access to data and capabilities within Oracle XML DB

The vulnerability does not require user interaction, making it particularly dangerous in environments where high-privileged accounts may be compromised through other means such as credential theft or insider threats.

Detection Methods for CVE-2021-2337

Indicators of Compromise

• Unusual activity from accounts with Create Any Procedure or Create Public Synonym privileges
• Unexpected creation of procedures or synonyms targeting Oracle XML DB objects
• Anomalous network connections to the Oracle Database via Oracle Net from untrusted sources
• Unauthorized modifications to XML DB stored content or configurations

Detection Strategies

• Monitor Oracle Database audit logs for privilege usage patterns involving Create Any Procedure and Create Public Synonym
• Implement database activity monitoring to detect suspicious procedure creation or synonym manipulation targeting XML DB schemas
• Review Oracle Net listener logs for abnormal connection patterns or attempts from unauthorized network segments
• Deploy SentinelOne Singularity Platform for endpoint detection to identify malicious actors attempting to access database servers

Monitoring Recommendations

• Enable Oracle Database auditing for all privileged operations, particularly those involving procedure creation and synonym management
• Configure alerts for any new procedures or synonyms created that reference Oracle XML DB components
• Establish baseline activity for privileged accounts and alert on deviations
• Implement network monitoring to detect anomalous Oracle Net traffic patterns

How to Mitigate CVE-2021-2337

Immediate Actions Required

• Apply the Oracle Critical Patch Update (CPU) from July 2021 immediately
• Review and audit all accounts with Create Any Procedure and Create Public Synonym privileges
• Restrict network access to Oracle Database servers to only authorized hosts and networks
• Implement the principle of least privilege by removing unnecessary privileges from database accounts

Patch Information

Oracle has addressed this vulnerability in the July 2021 Critical Patch Update. Organizations should apply the appropriate patches for their Oracle Database version:

• Oracle Database 12.1.0.2 - Apply the July 2021 CPU patch bundle
• Oracle Database 12.2.0.1 - Apply the July 2021 CPU patch bundle
• Oracle Database 19c - Apply the July 2021 CPU patch bundle

Patch downloads are available through Oracle Support. Organizations should follow Oracle's patching guidelines and test patches in non-production environments before deployment.

Workarounds

• Restrict Create Any Procedure and Create Public Synonym privileges to only essential accounts pending patch application
• Implement network segmentation to limit access to Oracle Database servers from untrusted networks
• Enable comprehensive database auditing to detect any exploitation attempts
• Consider temporarily disabling non-essential Oracle XML DB functionality if not required for business operations

# Configuration example: Audit privileged operations
# Enable auditing for procedure and synonym creation
ALTER SYSTEM SET audit_trail=db,extended SCOPE=SPFILE;
# Restart database to apply changes

# After restart, enable specific audits
AUDIT CREATE ANY PROCEDURE;
AUDIT CREATE PUBLIC SYNONYM;
AUDIT ALL ON SYS.DBMS_XMLSCHEMA BY ACCESS;