CVE-2025-49700: Microsoft Word Remote Code Execution via Use-After-Free
Summary:CVE-2025-49700 is a critical "use-after-free" vulnerability in Microsoft Office Word that allows unauthorized local code execution. It is exploitable through a manipulated Word document crafted to trigger the memory mismanagement condition within the application.
Technical Analysis
Root Cause:A use-after-free bug occurs when Microsoft Word erroneously tries to use memory it has already freed. If an attacker can control the contents of this freed memory (e.g., by getting a user to open a specially crafted document), malicious code can run on the victim’s system, usually with the same privileges as the user.
Exploit Scenario:
- The attacker crafts a malicious Word document.
- The document is delivered, typically via phishing or a direct file share.
- The victim opens the document in Word.
- Word attempts to use memory that has been freed but is now under the attacker's control.
- Attack code executes locally, potentially leading to privilege escalation or broader compromise, especially in enterprise environments.
Security Implications
- Local Code Execution: Attackers can run arbitrary code on affected systems if the user opens a malicious document.
- Potential for Escalation: Once local code execution is achieved, it can serve as a foothold for privilege escalation or lateral movement across an organization.
- Enterprise Impact: In business settings, a single compromised workstation could provide a tile in a broader network intrusion.
Best Practices and Mitigation
- Immediate Patch Deployment: Microsoft has released (or will release) patches for all supported Office versions. Deploy patches as soon as they become available.
- Enable Protected View: Keep Office’s Protected View enabled, especially for files originating from the internet or email.
- Restrict Macros: Disable macros unless strictly needed, as they are common exploit vectors.
- User Education: Train users not to open unsolicited or suspicious documents.
- Endpoint Security: Use reputable antivirus and Endpoint Detection and Response (EDR) solutions.
- Principle of Least Privilege: Ensure users do not operate with unnecessary admin privileges.
- Monitoring: Watch for suspicious Office process creation and unexpected file or network activity.
Check for updates manually, as these systems may not update automatically.
Enterprise Note:
Environments with legacy or unsupported Office versions are at the greatest risk. Unpatched endpoints can serve as entry points for attackers, especially if threat actors weaponize public proof-of-concept exploits.
Detection & Threat Intelligence
- Monitor for Office spawning unusual processes (e.g., PowerShell, cmd.exe).
- Watch %AppData% and %Temp% for unexpected file drops.
- Examine outbound traffic from Office apps for anomalies.
References
- Official Microsoft Security Advisory
- Further technical explanations and analogies are elaborated in internal threat intelligence summaries.
Summary Table
| Attribute | Details |
|---|---|
| CVE | CVE-2025-49700 |
| Vulnerability Type | Use-after-free (memory mismanagement) |
| Impact | Local remote code execution |
| Attack Vector | Malicious Word document |
| Mitigation | Patch, protected view, macro restriction, EDR |
| Detection | Unusual process/file/network activity from Word |
Patch ASAP and ensure robust user training and endpoint monitoring!
Source: MSRC Security Update Guide - Microsoft Security Response Center
