Critical Splunk Enterprise Vulnerabilities Expose Systems to Privilege Escalation
A significant security flaw has been identified in Splunk’s Enterprise and Universal Forwarder products for Windows, stemming from improper file permission settings during installation and upgrade processes. This vulnerability, cataloged as CVE-2025-20386 for Splunk Enterprise and CVE-2025-20387 for Universal Forwarder, allows non-administrator users to access and modify sensitive installation directories, potentially leading to privilege escalation attacks.
Understanding the Vulnerability
The issue arises when Splunk products are installed or updated on Windows systems. During these processes, the installation directories—specifically C:\Program Files\Splunk for Enterprise and C:\Program Files\SplunkUniversalForwarder for Universal Forwarder—are assigned incorrect permissions. This misconfiguration grants unprivileged local users read and write access to critical configuration files and executable binaries, which should be restricted to administrators.
An attacker with local access could exploit these permissions to alter system configurations, inject malicious code, or escalate their privileges to the administrator level. Splunk has rated both vulnerabilities with a CVSS score of 8.0, indicating high severity. The attack vector is network-adjacent, requiring authenticated access and user interaction, but the potential impact spans confidentiality, integrity, and availability of affected systems.
Immediate Remediation Steps
To address these vulnerabilities, Splunk has released patched versions:
– Splunk Enterprise: 10.0.2, 9.4.6, 9.3.8, and 9.2.10
– Splunk Universal Forwarder: 10.0.2, 9.4.6, 9.3.8, and 9.2.10
Organizations are strongly advised to upgrade to these versions promptly to mitigate the risk.
Mitigation Measures for Immediate Protection
For organizations unable to upgrade immediately, Splunk provides specific mitigation steps to reconfigure directory permissions:
1. Remove Inappropriate Access Rights:
Execute the following command as a Windows system administrator to remove the problematic permissions:
“`
icacls C:\Program Files\Splunk /remove:g BU /C
“`
This command targets the Built-in Users group (represented by BU) and removes their permissions from the installation directory.
2. Reapply Proper Inheritance Controls:
After removing inappropriate permissions, reapply the correct inheritance settings to ensure that only authorized users have access to the directory and its contents.
These mitigation steps should be applied in the following scenarios:
– New installations of affected versions
– Upgrades to affected versions
– Uninstallation and reinstallation of existing affected Splunk installations
Broader Implications and Recommendations
Splunk Enterprise is widely utilized in security operations across Fortune 500 companies and government agencies. The identified vulnerabilities affect all supported Windows versions, representing a significant supply chain risk if exploited in defended environments.
Organizations should prioritize patching and apply the necessary updates as soon as possible to mitigate the risk of exploitation. Regular security audits and adherence to best practices in access control can further enhance system security.
Conclusion
The discovery of these vulnerabilities underscores the importance of promptly applying security updates, especially for critical infrastructure and security monitoring tools like Splunk. By taking immediate action to upgrade or apply the recommended mitigations, organizations can protect their systems from potential privilege escalation attacks and maintain the integrity of their security operations.
