CVE-2023-40054: SolarWinds NCM RCE Vulnerability

CVE-2023-40054 Overview

CVE-2023-40054 is a Directory Traversal Remote Code Execution vulnerability affecting SolarWinds Network Configuration Manager. This vulnerability allows a low-privileged user to perform actions with SYSTEM-level privileges, representing a significant privilege escalation risk. Notably, this issue was discovered as an incomplete fix for the previously disclosed CVE-2023-33226, indicating that the original remediation did not fully address the underlying security flaw.

Critical Impact

Authenticated attackers with low-level privileges can leverage directory traversal techniques to execute arbitrary code with SYSTEM privileges, potentially leading to complete system compromise.

Affected Products

• SolarWinds Network Configuration Manager (versions prior to 2023.4.1)

Discovery Timeline

• 2023-11-09 - CVE-2023-40054 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-40054

Vulnerability Analysis

This vulnerability stems from improper input validation in the SolarWinds Network Configuration Manager, specifically related to path handling within the application. The vulnerability is classified under CWE-22 (Path Traversal), which occurs when the software uses external input to construct a pathname intended to identify a file or directory located underneath a restricted parent directory, but fails to properly neutralize special elements that can cause the pathname to resolve outside that directory.

The vulnerability is accessible over the network and requires only low-level authentication, meaning any authenticated user with minimal privileges can potentially exploit it. Once exploited, the attacker gains the ability to execute code with SYSTEM-level privileges, which represents the highest privilege level on Windows systems.

This vulnerability is particularly concerning because it represents an incomplete fix for CVE-2023-33226. This pattern of patch bypasses suggests that the initial remediation may have addressed specific attack vectors without fully mitigating the underlying input validation weakness.

Root Cause

The root cause is improper neutralization of special path elements (CWE-22) within the Network Configuration Manager application. The application fails to adequately sanitize user-supplied input that is used to construct file system paths. Attackers can inject directory traversal sequences (such as ../ or ..\) to escape the intended directory context and access or manipulate files in arbitrary locations on the file system.

Attack Vector

The attack is network-based, requiring authentication with a low-privilege account. The attacker submits crafted requests containing directory traversal sequences to the vulnerable application endpoint. When the application processes these malicious inputs without proper validation, it allows file operations outside the intended directory structure. By targeting specific system locations or uploading malicious files to executable paths, the attacker can achieve code execution with SYSTEM privileges.

The exploitation does not require user interaction, making it suitable for automated attack scenarios once valid credentials are obtained. Given that the vulnerability affects network infrastructure management software, successful exploitation could provide attackers with control over network device configurations and potentially pivot to other systems in the environment.

Detection Methods for CVE-2023-40054

Indicators of Compromise

• Unusual file access patterns in NCM logs showing directory traversal sequences (../, ..\, %2e%2e/)
• Unexpected file modifications or creations in system directories by the NCM service account
• Process execution chains showing SYSTEM-level processes spawned from NCM application components
• Authentication events from low-privilege accounts followed by privileged operations

Detection Strategies

• Monitor NCM application logs for requests containing path traversal patterns or encoded traversal sequences
• Implement file integrity monitoring on critical system directories to detect unauthorized modifications
• Deploy endpoint detection rules to identify anomalous process behavior originating from NCM services
• Analyze network traffic for suspicious requests to NCM endpoints containing traversal characters

Monitoring Recommendations

• Enable verbose logging on SolarWinds NCM to capture detailed request information
• Configure SIEM rules to correlate low-privilege authentication with subsequent privileged file operations
• Monitor Windows Security Event Log for unusual service account activity related to NCM
• Implement behavioral analysis to detect deviations from normal NCM operational patterns

How to Mitigate CVE-2023-40054

Immediate Actions Required

• Upgrade SolarWinds Network Configuration Manager to version 2023.4.1 or later immediately
• Audit user accounts with access to NCM and remove unnecessary privileges
• Review NCM logs for any historical exploitation attempts
• Restrict network access to NCM management interfaces to trusted administrative networks only

Patch Information

SolarWinds has released version 2023.4.1 of Network Configuration Manager to address this vulnerability. Organizations should apply this update as soon as possible. Detailed patch information is available in the SolarWinds NCM 2023.4.1 Release Notes and the SolarWinds Security Advisory for CVE-2023-40054.

Workarounds

• Implement network segmentation to limit access to NCM interfaces from untrusted networks
• Enforce principle of least privilege for all NCM user accounts
• Deploy web application firewall rules to block requests containing directory traversal patterns
• Consider temporarily disabling vulnerable functionality if patching cannot be performed immediately

# Network segmentation example using Windows Firewall
# Restrict NCM access to specific administrative subnet
netsh advfirewall firewall add rule name="Restrict NCM Access" dir=in action=allow protocol=TCP localport=443 remoteip=10.0.1.0/24
netsh advfirewall firewall add rule name="Block NCM External" dir=in action=block protocol=TCP localport=443 remoteip=any