CVE-2023-20858: VMware Carbon Black App Control RCE Flaw

CVE-2023-20858 Overview

VMware Carbon Black App Control contains an injection vulnerability (CWE-74) that affects multiple versions of the application control platform. A malicious actor with privileged access to the App Control administration console may be able to use specially crafted input allowing access to the underlying server operating system. This vulnerability requires the attacker to already have administrative privileges to the management console, but successful exploitation could lead to complete compromise of the underlying host system.

Critical Impact

Attackers with privileged access to the VMware Carbon Black App Control administration console can exploit this injection vulnerability to gain unauthorized access to the underlying server operating system, potentially compromising the entire endpoint security infrastructure.

Affected Products

• VMware Carbon Black App Control 8.7.x prior to 8.7.8
• VMware Carbon Black App Control 8.8.x prior to 8.8.6
• VMware Carbon Black App Control 8.9.x prior to 8.9.4

Discovery Timeline

• 2023-02-22 - CVE CVE-2023-20858 published to NVD
• 2025-03-17 - Last updated in NVD database

Technical Details for CVE-2023-20858

Vulnerability Analysis

This vulnerability is classified as an Injection vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component). The flaw exists within the VMware Carbon Black App Control administration console, which fails to properly sanitize user-supplied input. When a privileged administrator submits specially crafted input through the management interface, the application does not adequately validate or neutralize special elements before passing them to downstream components.

The network-accessible attack vector means that exploitation can be performed remotely by any authenticated administrator with console access. While high privileges are required to access the vulnerable functionality, the potential impact is severe—successful exploitation grants attackers access to the underlying Windows server operating system with the same privileges as the Carbon Black App Control service.

Root Cause

The root cause of CVE-2023-20858 is improper input validation within the App Control administration console. The application fails to properly neutralize special elements in user-controlled input before using that input in operations that interact with the underlying operating system. This allows specially crafted payloads to escape the intended context and execute commands or access resources on the host server.

Attack Vector

The attack requires network access to the VMware Carbon Black App Control administration console and valid administrative credentials. Once authenticated, an attacker can craft malicious input through the console interface. The injection payload bypasses input validation mechanisms and interacts directly with the underlying Windows operating system.

The attack flow involves: gaining legitimate administrative access to the console, identifying input fields vulnerable to injection, crafting payloads that exploit insufficient input sanitization, and submitting the malicious input to gain operating system access. The vulnerability does not require user interaction beyond the attacker's own actions in the administrative console.

Detection Methods for CVE-2023-20858

Indicators of Compromise

• Unusual or unexpected commands executed by the Carbon Black App Control service process
• Anomalous administrative console activity including unusual input patterns or repeated failed attempts
• Unexpected process spawning from the Carbon Black App Control server application
• Unauthorized changes to system configurations or files on the App Control server

Detection Strategies

• Monitor administrative console access logs for suspicious activity patterns or unusual administrative actions
• Implement alerting for any unexpected child processes spawned by the Carbon Black App Control service
• Review audit logs for administrative sessions with unusual input characteristics or error patterns
• Deploy behavioral analytics to detect anomalous activity from the App Control server

Monitoring Recommendations

• Enable verbose logging on the VMware Carbon Black App Control administration console
• Implement SIEM rules to correlate administrative login events with suspicious server-side activity
• Monitor network traffic to and from the App Control server for unusual patterns
• Establish baseline behavior for administrative activities to identify deviations

How to Mitigate CVE-2023-20858

Immediate Actions Required

• Upgrade VMware Carbon Black App Control to patched versions: 8.7.8, 8.8.6, or 8.9.4 or later
• Restrict administrative console access to only essential personnel using network segmentation
• Review administrative account privileges and remove unnecessary access
• Audit recent administrative console activity for signs of exploitation attempts

Patch Information

VMware has released security patches addressing this vulnerability. Customers should upgrade to the following versions immediately:

• Version 8.7.x: Upgrade to 8.7.8 or later
• Version 8.8.x: Upgrade to 8.8.6 or later
• Version 8.9.x: Upgrade to 8.9.4 or later

Refer to the VMware Security Advisory VMSA-2023-0004 for complete patch details and download links.

Workarounds

• Implement strict network access controls to limit who can reach the administration console
• Enable multi-factor authentication for all administrative accounts if supported
• Monitor administrative sessions closely and terminate suspicious connections immediately
• Consider temporarily limiting administrative access until patching can be completed

# Network segmentation example - restrict console access
# Add firewall rules to limit access to App Control admin console (example port 443)
# Only allow access from trusted management network segments
netsh advfirewall firewall add rule name="Restrict CB App Control Admin" dir=in action=allow protocol=tcp localport=443 remoteip=10.0.100.0/24
netsh advfirewall firewall add rule name="Block CB App Control Admin Default" dir=in action=block protocol=tcp localport=443