CVE-2024-23678: Splunk Enterprise Path Traversal Flaw

CVE-2024-23678 Overview

CVE-2024-23678 is an unsafe deserialization vulnerability affecting Splunk Enterprise for Windows. The vulnerability exists because Splunk Enterprise does not correctly sanitize path input data, which results in the unsafe deserialization of untrusted data from a separate disk partition on the machine. This vulnerability is specific to Windows deployments of Splunk Enterprise.

Critical Impact

Attackers with local access can exploit improper path sanitization to trigger unsafe deserialization, potentially leading to code execution with the privileges of the Splunk Enterprise service.

Affected Products

• Splunk Enterprise for Windows versions below 9.0.8
• Splunk Enterprise for Windows versions below 9.1.3

Discovery Timeline

• 2024-01-22 - CVE-2024-23678 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-23678

Vulnerability Analysis

This vulnerability stems from improper input validation (CWE-20) in how Splunk Enterprise for Windows handles path input data. The application fails to properly sanitize file paths, allowing an attacker to reference data from a separate disk partition. When this unsanitized path data is processed, it leads to the deserialization of untrusted data, which can be leveraged for malicious purposes.

The local attack vector requires the attacker to have some level of access to the Windows machine running Splunk Enterprise. Once achieved, the attacker can manipulate path inputs to point to attacker-controlled serialized objects on another disk partition. When Splunk Enterprise deserializes this data without proper validation, it can lead to arbitrary code execution or other security compromises.

The scope of this vulnerability is changed, meaning successful exploitation can impact resources beyond the vulnerable component itself, potentially affecting the confidentiality, integrity, and availability of the entire system.

Root Cause

The root cause is improper input validation in Splunk Enterprise's path handling logic on Windows systems. The application does not adequately sanitize or validate path input data before using it in deserialization operations. This allows attackers to craft malicious paths that reference untrusted serialized data from alternate disk partitions, bypassing intended security boundaries.

Attack Vector

The attack vector is local, requiring an attacker to have existing access to the Windows machine running Splunk Enterprise. The attack flow involves:

1. The attacker gains local access to a Windows system running a vulnerable version of Splunk Enterprise
2. The attacker places malicious serialized data on a disk partition accessible from the target system
3. The attacker crafts input that manipulates path handling to reference the malicious serialized data
4. Splunk Enterprise processes the unsanitized path and deserializes the untrusted data
5. The malicious payload executes within the context of the Splunk Enterprise service

The vulnerability does not require user interaction and can be exploited with low privilege levels, though the changed scope indicates impacts can extend beyond the Splunk Enterprise component.

Detection Methods for CVE-2024-23678

Indicators of Compromise

• Unexpected file access patterns on non-standard disk partitions by Splunk Enterprise processes
• Anomalous deserialization activity in Splunk Enterprise logs or process behavior
• Unusual child processes spawned by splunkd.exe or related Splunk services
• Evidence of serialized object files placed on secondary disk partitions

Detection Strategies

• Monitor Splunk Enterprise process activity for file operations targeting unexpected disk partitions
• Implement file integrity monitoring on Splunk Enterprise installation directories
• Review Splunk internal logs for deserialization errors or path manipulation attempts
• Leverage the Splunk Research Analysis detection rule for behavioral detection

Monitoring Recommendations

• Enable detailed audit logging for file system access on Windows systems running Splunk Enterprise
• Monitor process execution chains originating from Splunk Enterprise services
• Implement endpoint detection and response (EDR) solutions to identify suspicious deserialization behavior
• Configure alerts for Splunk Enterprise accessing files from non-standard paths or partitions

How to Mitigate CVE-2024-23678

Immediate Actions Required

• Upgrade Splunk Enterprise for Windows to version 9.0.8 or later (for 9.0.x branch)
• Upgrade Splunk Enterprise for Windows to version 9.1.3 or later (for 9.1.x branch)
• Review file system access logs for any indicators of prior exploitation
• Restrict local access to systems running Splunk Enterprise to authorized personnel only

Patch Information

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

• Splunk Enterprise 9.0.x: Upgrade to version 9.0.8 or later
• Splunk Enterprise 9.1.x: Upgrade to version 9.1.3 or later

For detailed patch information and upgrade instructions, refer to the Splunk Security Advisory SVD-2024-0108.

Workarounds

• Limit local access to Windows systems running Splunk Enterprise to essential personnel only
• Implement strict access controls on all disk partitions to prevent placement of malicious serialized data
• Monitor and restrict Splunk Enterprise service account permissions to minimize potential impact
• Consider network segmentation to isolate Splunk Enterprise systems from less trusted network segments