CVE-2023-21975: Oracle APEX Auth Bypass Vulnerability

CVE-2023-21975 Overview

CVE-2023-21975 is a critical vulnerability in the Application Express Customers Plugin product of Oracle Application Express, specifically affecting the User Account component. This vulnerability enables a low-privileged attacker with network access via HTTP to potentially achieve complete takeover of the Application Express Customers Plugin. The attack requires human interaction from a person other than the attacker, and successful exploitation can significantly impact additional products beyond the vulnerable component (scope change).

Critical Impact

Successful exploitation allows complete takeover of the Application Express Customers Plugin with full confidentiality, integrity, and availability impact, potentially affecting additional products in the environment.

Affected Products

• Oracle Application Express Customers Plugin versions 18.2 through 22.2
• Oracle Application Express (APEX) deployments using the Customers Plugin
• Web applications built on affected APEX versions with User Account functionality

Discovery Timeline

• 2023-07-18 - CVE-2023-21975 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-21975

Vulnerability Analysis

This vulnerability resides in the User Account component of the Oracle Application Express Customers Plugin. The flaw is classified as easily exploitable, meaning that once an attacker has established network access and possesses low-level privileges, the technical barriers to exploitation are minimal. The attack requires user interaction, suggesting a social engineering component where the victim must be induced to perform an action that triggers the vulnerability.

The scope change characteristic indicates that successful exploitation can pivot beyond the vulnerable Application Express Customers Plugin to affect other components or systems within the deployment environment. This cross-boundary impact significantly increases the potential damage radius of an attack.

Root Cause

While Oracle has not disclosed specific technical details about the root cause, the vulnerability characteristics suggest an access control or privilege escalation issue within the User Account component. The combination of low privilege requirements, human interaction necessity, and scope change behavior indicates that the vulnerability likely involves improper validation of user-controlled input or insufficient authorization checks during account-related operations.

The User Account component handles authentication and authorization workflows, making it a high-value target where access control weaknesses can lead to privilege escalation or account takeover scenarios.

Attack Vector

The attack vector is network-based, accessible via HTTP, which means the vulnerability can be exploited remotely without requiring local access to the target system. The attack flow involves:

1. An attacker with low-level privileges (authenticated user) identifies a vulnerable Oracle APEX deployment running the Customers Plugin versions 18.2 through 22.2
2. The attacker crafts a malicious request or manipulates the User Account functionality
3. Social engineering or phishing is used to induce a victim with higher privileges to interact with the malicious content
4. Upon victim interaction, the attacker gains unauthorized access to the Application Express Customers Plugin, potentially achieving full account takeover

The requirement for human interaction adds a social engineering dimension to the attack, but does not significantly reduce the exploitability given the common success rates of phishing and similar techniques in enterprise environments.

Detection Methods for CVE-2023-21975

Indicators of Compromise

• Unusual HTTP requests targeting Oracle APEX User Account endpoints with anomalous parameters
• Unexpected privilege changes or account modifications in APEX Customers Plugin audit logs
• Cross-origin or suspicious session activity indicating potential scope change exploitation
• Authentication anomalies where low-privileged users access high-privilege functionality

Detection Strategies

• Monitor Oracle APEX access logs for unusual patterns in User Account component requests
• Implement web application firewall (WAF) rules to detect exploitation attempts against APEX endpoints
• Configure application-level auditing to track all User Account modifications and privilege changes
• Deploy SentinelOne Singularity Platform for real-time behavioral detection of post-exploitation activities

Monitoring Recommendations

• Enable detailed logging for Oracle Application Express Customers Plugin operations
• Review authentication logs for session anomalies and unauthorized access patterns
• Monitor network traffic for unusual HTTP requests to APEX infrastructure
• Establish baseline behavior for User Account operations to detect deviation

How to Mitigate CVE-2023-21975

Immediate Actions Required

• Verify your Oracle Application Express Customers Plugin version and determine if it falls within the affected range (18.2 through 22.2)
• Apply the security patch from Oracle's July 2023 Critical Patch Update immediately
• Review User Account activity logs for any signs of previous exploitation attempts
• Implement network segmentation to limit exposure of APEX deployments to untrusted networks

Patch Information

Oracle has addressed this vulnerability in their July 2023 Critical Patch Update. Administrators should consult the Oracle Security Alerts July 2023 advisory for detailed patching instructions and download the appropriate updates for their APEX environment.

Organizations running Application Express Customers Plugin versions 18.2 through 22.2 should prioritize this update given the critical severity and potential for complete system takeover.

Workarounds

• Restrict network access to Oracle APEX deployments using firewall rules and network segmentation
• Implement additional authentication controls such as multi-factor authentication for APEX administrative functions
• Deploy a web application firewall (WAF) with rules to monitor and filter suspicious requests to User Account endpoints
• Conduct user awareness training to reduce the risk of social engineering attacks that could trigger the vulnerability

# Example: Restrict APEX access to trusted networks using iptables
# Adjust IP ranges according to your environment
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP