CVE-2025-27744: Microsoft Office Privilege Escalation Flaw

CVE-2025-27744 Overview

CVE-2025-27744 is an improper access control vulnerability in Microsoft Office that allows an authenticated local attacker to elevate privileges on an affected system. The flaw is tracked under CWE-284: Improper Access Control and affects Microsoft Office 2016 (x64) among impacted builds. An attacker with local, low-privileged access can leverage the weakness to gain higher privileges, compromising confidentiality, integrity, and availability of the host. Microsoft published the advisory in April 2025, and no public proof-of-concept or in-the-wild exploitation has been reported to date.

Critical Impact
Successful exploitation grants an authenticated local attacker elevated privileges on the target host, enabling full compromise of Office data and potential lateral movement.

Affected Products

Microsoft Office 2016 (x64)
Additional Microsoft Office builds listed in the vendor advisory
Systems running vulnerable Office components prior to the April 2025 security update

Discovery Timeline

2025-04-08 - CVE-2025-27744 published to the National Vulnerability Database
2025-04-08 - Microsoft released the security update addressing the vulnerability
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-27744

Vulnerability Analysis

The vulnerability stems from improper access control within Microsoft Office components. Office fails to correctly enforce permission boundaries between processes or resources that operate at different trust levels on the local host. An authenticated attacker with basic user privileges can abuse this weak enforcement to perform actions reserved for a higher-privileged principal. The outcome is local privilege elevation on the affected Windows system, which can be chained with initial access techniques such as phishing or malicious document delivery.

Root Cause

The root cause maps to CWE-284: Improper Access Control. Microsoft Office does not sufficiently validate or restrict access to a resource that should be protected against lower-privileged callers. Because the attacker is already authorized at a low level, the missing access check enables the elevation path. Microsoft has not published low-level technical details in the advisory to limit exposure prior to patch adoption.

Attack Vector

Exploitation requires local access and low privileges, with no user interaction. A typical scenario involves an attacker who has already obtained code execution as a standard user, for example through a malicious Office document or a compromised account. The attacker then invokes the vulnerable Office component to bypass access checks and execute actions in a higher-privileged context. Public exploit code is not currently available, and the EPSS score reflects a relatively low near-term exploitation probability.

No verified public proof-of-concept code is available. See the Microsoft CVE-2025-27744 Advisory for authoritative vendor details.

Detection Methods for CVE-2025-27744

Indicators of Compromise

Unexpected child processes spawned by winword.exe, excel.exe, or other Office binaries running with elevated integrity.
Creation or modification of files under privileged directories by an Office process owned by a standard user.
Anomalous loading of unsigned or user-writable DLLs by Office applications.

Detection Strategies

Baseline normal Office process trees and alert on deviations, particularly privilege transitions from Medium to High integrity.
Correlate Office document open events with subsequent creation of scheduled tasks, services, or registry autoruns.
Hunt for Office processes accessing sensitive tokens, LSASS, or performing writes to %ProgramFiles% and HKLM hives.

Monitoring Recommendations

Enable Microsoft Defender Attack Surface Reduction (ASR) rules that block Office child process creation and code injection.
Ingest Sysmon Event IDs 1, 10, and 11 into your SIEM to track Office process lineage, handle access, and file writes.
Monitor Windows Security event 4688 for elevated processes launched by Office parents on standard user sessions.

How to Mitigate CVE-2025-27744

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft CVE-2025-27744 Advisory across all affected Office installations.
Inventory endpoints running Microsoft Office 2016 x64 and other impacted builds, and prioritize patching for privileged user workstations.
Restrict local administrative rights and enforce least privilege to reduce the population of accounts positioned to exploit the flaw.

Patch Information

Microsoft released a security update for CVE-2025-27744 on April 8, 2025. Administrators should deploy the update through Microsoft Update, Microsoft 365 Apps update channels, or WSUS, and validate build versions post-installation. Refer to the Microsoft CVE-2025-27744 Advisory for the definitive list of affected products and fixed builds.

Workarounds

Enable Attack Surface Reduction rules that block Office applications from creating child processes and injecting code into other processes.
Disable macros from the internet through Group Policy to reduce the initial access paths that precede local privilege elevation.
Apply application control policies such as Windows Defender Application Control (WDAC) to prevent unauthorized binaries from loading into Office processes.

bash

# Enable ASR rules via PowerShell to reduce Office-based attack paths
Set-MpPreference -AttackSurfaceReductionRules_Ids `
  D4F940AB-401B-4EFC-AADC-AD5F3C50688A `
  -AttackSurfaceReductionRules_Actions Enabled

# Block Office child process creation (Enabled = 1)
# Rule GUID above corresponds to "Block all Office applications from creating child processes"