CVE-2024-45731: Splunk Enterprise Path Traversal Flaw

CVE-2024-45731 Overview

CVE-2024-45731 is a path traversal vulnerability affecting Splunk Enterprise for Windows that allows low-privileged users to write files to the Windows system root directory. When Splunk Enterprise is installed on a separate drive from the Windows system, an attacker with basic user access (not requiring "admin" or "power" Splunk roles) can exploit this flaw to write arbitrary files to sensitive system locations, with the default target being the Windows System32 folder.

Critical Impact

A low-privileged attacker can write malicious files to the Windows System32 folder, potentially leading to privilege escalation, persistence, or complete system compromise.

Affected Products

• Splunk Enterprise for Windows versions below 9.3.1
• Splunk Enterprise for Windows versions below 9.2.3
• Splunk Enterprise for Windows versions below 9.1.6

Discovery Timeline

• 2024-10-14 - CVE CVE-2024-45731 published to NVD
• 2024-10-17 - Last updated in NVD database

Technical Details for CVE-2024-45731

Vulnerability Analysis

This vulnerability is classified under CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-23 (Relative Path Traversal). The flaw exists in how Splunk Enterprise for Windows handles file path construction when the application is installed on a drive separate from the Windows system drive.

When Splunk Enterprise is deployed to a non-system drive (e.g., D:\Splunk while Windows resides on C:\), the application fails to properly validate and restrict file paths during certain write operations. This allows a low-privileged user—one who does not hold the "admin" or "power" Splunk roles—to craft requests that traverse outside the intended Splunk directory structure and write files directly to the Windows system root directory.

The default location for Windows System32 makes this particularly dangerous, as files written to this directory can be leveraged for DLL hijacking, service manipulation, or establishing persistent backdoors on the compromised system.

Root Cause

The root cause of CVE-2024-45731 is improper path validation in Splunk Enterprise for Windows. The application fails to adequately sanitize user-controlled input used in file path construction, allowing relative path traversal sequences to escape the intended directory structure. This is exacerbated when Splunk is installed on a different drive than the Windows system, as the path normalization logic does not correctly handle cross-drive path traversal attempts.

Attack Vector

The vulnerability is exploitable over the network by authenticated users with minimal privileges. An attacker requires valid credentials for the Splunk instance but does not need elevated roles such as "admin" or "power." The attack requires some user interaction, and exploitation allows the attacker to:

1. Authenticate to the Splunk Enterprise instance with a low-privileged account
2. Craft a malicious request containing path traversal sequences
3. Write arbitrary files to the Windows System32 folder or other sensitive system directories
4. Leverage the written files for privilege escalation, persistence, or further compromise

This attack is particularly effective in enterprise environments where Splunk installations are commonly deployed on dedicated data drives while Windows resides on the system drive.

Detection Methods for CVE-2024-45731

Indicators of Compromise

• Unexpected file creation events in the Windows System32 directory originating from Splunk processes
• Anomalous write operations by low-privileged Splunk users targeting system directories
• File system audit logs showing path traversal patterns such as ..\..\ in Splunk-related file operations
• New or modified DLL files in System32 that correlate with Splunk user activity timestamps

Detection Strategies

• Enable Windows file system auditing on the System32 directory and monitor for writes from the Splunk service account
• Implement Splunk's own detection content available at Splunk Research Analysis Document
• Deploy endpoint detection rules to alert on path traversal patterns in Splunk web requests or API calls
• Monitor Splunk audit logs for file write operations by users without admin or power roles

Monitoring Recommendations

• Configure SentinelOne to detect and alert on suspicious file creation in Windows system directories by non-system processes
• Establish baseline behavior for Splunk service accounts and alert on deviations, particularly file operations outside the Splunk installation directory
• Implement network-level monitoring to detect POST requests containing path traversal sequences targeting Splunk endpoints

How to Mitigate CVE-2024-45731

Immediate Actions Required

• Upgrade Splunk Enterprise for Windows to version 9.3.1, 9.2.3, or 9.1.6 or later immediately
• If immediate patching is not possible, consider installing Splunk Enterprise on the same drive as the Windows system as a temporary mitigation
• Review Splunk audit logs for any historical exploitation attempts by low-privileged users
• Audit user accounts with access to Splunk and ensure principle of least privilege is enforced

Patch Information

Splunk has released security updates to address this vulnerability. Organizations should upgrade to the following patched versions:

• Splunk Enterprise 9.3.1 or later (for 9.3.x branch)
• Splunk Enterprise 9.2.3 or later (for 9.2.x branch)
• Splunk Enterprise 9.1.6 or later (for 9.1.x branch)

Detailed patch information and upgrade instructions are available in the Splunk Security Advisory SVD-2024-1001.

Workarounds

• Consider reinstalling Splunk Enterprise on the same drive as Windows if patching cannot be performed immediately
• Restrict network access to the Splunk web interface to trusted IP ranges only
• Temporarily disable or restrict access for low-privileged Splunk user accounts until patches can be applied
• Implement additional file system permissions to prevent the Splunk service account from writing to system directories

# Verify current Splunk Enterprise version
$SPLUNK_HOME/bin/splunk version

# Example: Check if Splunk is installed on a separate drive from Windows
# If Splunk is on D:\ and Windows is on C:\, this configuration is vulnerable