Analysis Summary

Elastic has disclosed a high-severity vulnerability (CVE-2025-37735) in Elastic Defend for Windows, which could allow attackers to escalate privileges on affected systems. The flaw, designated as ESA-2025-23, stems from improper preservation of file permissions within the Elastic Defend service that operates with SYSTEM-level privileges. Since SYSTEM is the highest privilege level in Windows, any mismanagement of permissions within this service creates a critical security risk, enabling attackers to manipulate or delete system files and potentially gain full administrative control.

The vulnerability specifically exists in how Elastic Defend handles file permissions on Windows hosts. Attackers with local access could exploit the issue to delete arbitrary files, which in certain conditions, may lead to local privilege escalation. This makes the vulnerability a valuable tool for adversaries seeking to strengthen their foothold after compromising a lower-privilege account. Although exploitation requires local access and elevated privileges, the flaw does not require user interaction, increasing its potential impact across enterprise environments running Elastic Defend.

According to Elastic’s advisory, the flaw affects Elastic Defend versions up to and including 8.19.5, as well as versions 9.0.0 through 9.1.5. The issue has been addressed in versions 8.19.6, 9.1.6, and 9.2.0, which fix the improper permission handling mechanism. The vulnerability holds a CVSS score(High), indicating significant risk to organizations using outdated builds. As Elastic Defend is widely deployed in enterprise environments for endpoint protection, this makes the flaw an attractive target for threat actors aiming to escalate privileges within compromised networks.

Elastic urges all users to immediately upgrade to the fixed versions to mitigate potential exploitation. For organizations unable to patch right away, Windows 11 24H2 introduces architectural hardening that reduces the likelihood of successful exploitation, serving as a temporary mitigation. However, upgrading Elastic Defend remains the primary remediation. Enterprises should prioritize patching and review system permissions to ensure no unauthorized modifications have occurred, while also incorporating robust patch management and endpoint monitoring practices to prevent privilege escalation in the future.

Impact

• Privilege Escalation
• Gain Access

Indicators of Compromise

CVE

• CVE-2025-37735

Affected Vendors

Remediation

• Upgrade Elastic Defend to fixed versions 8.19.6, 9.1.6, or 9.2.0 as the primary remediation.
• Verify all deployed agents to ensure no systems are running 8.19.5 or earlier, or 9.0.0–9.1.5.
• Isolate and limit access to unpatched systems until upgrades are completed.
• Apply least-privilege principles and restrict local administrative rights to minimize exploitation potential.
• Temporarily mitigate by upgrading to Windows 11 24H2 if immediate patching is not possible, as it includes exploitation-hardening features.
• Audit system and security logs for unusual file deletions or permission changes initiated by the Elastic Defend service.
• Monitor for indicators of privilege escalation, unauthorized admin account creation, or lateral movement on affected endpoints.