CVE-2024-36984: Splunk Enterprise RCE Vulnerability

CVE-2024-36984 Overview

CVE-2024-36984 is an insecure deserialization vulnerability affecting Splunk Enterprise on Windows platforms. This flaw allows authenticated users to execute specially crafted queries that serialize untrusted data, ultimately enabling arbitrary code execution on affected systems. The vulnerability stems from improper handling of serialized data within Splunk's query processing mechanism, classified as CWE-502 (Deserialization of Untrusted Data).

Critical Impact

Authenticated attackers can leverage this vulnerability to execute arbitrary code on Splunk Enterprise servers running on Windows, potentially leading to complete system compromise, data exfiltration, or lateral movement within enterprise environments.

Affected Products

• Splunk Enterprise versions below 9.2.2
• Splunk Enterprise versions below 9.1.5
• Splunk Enterprise versions below 9.0.10

Discovery Timeline

• 2024-07-01 - CVE-2024-36984 published to NVD
• 2025-03-07 - Last updated in NVD database

Technical Details for CVE-2024-36984

Vulnerability Analysis

This vulnerability exploits improper input validation within Splunk Enterprise's query processing functionality on Windows systems. When an authenticated user submits a specially crafted query, the application fails to properly validate serialized data before processing it. This insecure deserialization flaw allows attackers to inject malicious serialized objects that execute arbitrary code when deserialized by the Splunk server.

The attack requires network access and valid authentication credentials, but once these prerequisites are met, the exploitation complexity is relatively low. Successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected system, as the attacker gains the ability to execute code with the privileges of the Splunk service.

Root Cause

The root cause of CVE-2024-36984 is classified as CWE-502: Deserialization of Untrusted Data. Splunk Enterprise on Windows fails to implement adequate validation and sanitization of serialized data within query processing. This allows attackers to craft malicious serialized payloads that, when processed by the application, instantiate dangerous objects or execute arbitrary code.

Insecure deserialization vulnerabilities occur when applications accept serialized objects from untrusted sources without proper verification of the object's type, structure, or content. In this case, the query mechanism accepts user-controlled serialized data that is subsequently deserialized in a dangerous context.

Attack Vector

The attack vector for this vulnerability is network-based, requiring authenticated access to the Splunk Enterprise instance. An attacker would need to:

1. Obtain valid credentials for the Splunk Enterprise system (low-privilege user access is sufficient)
2. Craft a malicious query containing serialized payload designed to exploit the deserialization flaw
3. Submit the query through Splunk's query interface
4. The malicious serialized data is processed by the server, triggering code execution

The vulnerability affects only Windows deployments of Splunk Enterprise. The attacker can leverage this to execute arbitrary commands with the privileges of the Splunk service account, potentially escalating to full system compromise.

For detailed technical information on the exploitation mechanism, refer to the Splunk Security Advisory SVD-2024-0704 and the Splunk Research Application Analysis.

Detection Methods for CVE-2024-36984

Indicators of Compromise

• Unusual or complex queries submitted by authenticated users that contain encoded or obfuscated content
• Unexpected process spawning from the Splunk service process on Windows systems
• Anomalous network connections originating from the Splunk server to external destinations
• Modifications to Splunk configuration files or unauthorized script execution within the Splunk directory

Detection Strategies

• Implement Splunk's own detection content available at their Research Application Analysis to identify exploitation attempts
• Monitor Splunk query logs for suspicious serialized data patterns or unusually complex query structures
• Deploy endpoint detection and response (EDR) solutions to detect anomalous process behavior from the Splunk service
• Enable Windows process creation auditing to capture child processes spawned by Splunk services

Monitoring Recommendations

• Enable verbose logging for Splunk query processing and review logs for deserialization-related errors
• Configure SIEM alerts for authentication anomalies followed by suspicious query patterns
• Monitor file system integrity for unauthorized modifications within Splunk installation directories
• Implement network segmentation to detect and alert on unusual outbound connections from Splunk servers

How to Mitigate CVE-2024-36984

Immediate Actions Required

• Upgrade Splunk Enterprise to version 9.2.2, 9.1.5, or 9.0.10 or later depending on your version branch
• Review and audit user accounts with access to Splunk Enterprise, removing unnecessary privileges
• Implement network segmentation to limit exposure of Splunk servers to trusted networks only
• Enable enhanced logging and monitoring to detect potential exploitation attempts

Patch Information

Splunk has released patches addressing this vulnerability in the following versions:

• Splunk Enterprise 9.2.2 and later (for 9.2.x branch)
• Splunk Enterprise 9.1.5 and later (for 9.1.x branch)
• Splunk Enterprise 9.0.10 and later (for 9.0.x branch)

Organizations should prioritize patching Windows-based Splunk Enterprise deployments immediately. Refer to the Splunk Security Advisory SVD-2024-0704 for official patch information and download links.

Workarounds

• Restrict network access to Splunk Enterprise instances using firewall rules to allow only trusted IP addresses
• Implement additional authentication controls such as multi-factor authentication (MFA) to reduce risk of credential compromise
• Review and minimize user permissions, ensuring users have only the minimum necessary privileges
• Consider temporarily disabling non-essential Splunk functionality until patches can be applied

# Example: Restrict Splunk web interface access via Windows Firewall
netsh advfirewall firewall add rule name="Restrict Splunk Web" dir=in action=allow protocol=TCP localport=8000 remoteip=10.0.0.0/8
netsh advfirewall firewall add rule name="Block Splunk Web External" dir=in action=block protocol=TCP localport=8000