CVE-2023-28287: Microsoft Publisher RCE Vulnerability

CVE-2023-28287 Overview

CVE-2023-28287 is a remote code execution vulnerability affecting Microsoft Publisher, a desktop publishing application included in Microsoft Office suites. This vulnerability allows attackers to execute arbitrary code on target systems when users open specially crafted Publisher documents. The attack requires user interaction, making social engineering and phishing campaigns likely attack vectors for exploitation.

Critical Impact

Successful exploitation of this vulnerability enables attackers to execute arbitrary code with the privileges of the current user, potentially leading to complete system compromise, data theft, or lateral movement within enterprise networks.

Affected Products

• Microsoft 365 Apps for Enterprise
• Microsoft Office 2019
• Microsoft Office Long Term Servicing Channel 2021
• Microsoft Publisher 2013 SP1
• Microsoft Publisher 2016

Discovery Timeline

• 2023-06-17 - CVE-2023-28287 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-28287

Vulnerability Analysis

CVE-2023-28287 is classified as a Use After Free (CWE-416) vulnerability in Microsoft Publisher. Use After Free vulnerabilities occur when an application continues to use a pointer after the memory it references has been freed. In this case, the vulnerability exists in how Microsoft Publisher processes certain document elements.

When a user opens a maliciously crafted Publisher document, the application may improperly handle memory during document parsing operations. An attacker who successfully exploits this vulnerability could execute arbitrary code in the context of the current user. If the current user is logged on with administrative privileges, an attacker could take complete control of the affected system, install programs, view, change, or delete data, or create new accounts with full user rights.

Root Cause

The root cause of this vulnerability is improper memory management in Microsoft Publisher's document processing functionality. The application fails to properly validate memory references after deallocation, leading to a Use After Free condition. When the freed memory is subsequently accessed, the application may execute attacker-controlled code that has been placed in that memory location.

Attack Vector

The attack vector for CVE-2023-28287 is local, requiring user interaction to trigger the vulnerability. An attacker must convince a user to open a specially crafted Microsoft Publisher file (.pub extension). This can be achieved through various social engineering techniques:

The attacker would craft a malicious Publisher document containing specially formatted content designed to trigger the Use After Free condition. The document would then be delivered to the victim via email attachment, malicious website download, file sharing services, or other means. When the victim opens the document in Microsoft Publisher, the vulnerability is triggered, allowing the attacker's code to execute.

Detection Methods for CVE-2023-28287

Indicators of Compromise

• Suspicious Microsoft Publisher files (.pub) received via email or downloaded from untrusted sources
• Unexpected Publisher process behavior including crashes or unusual memory consumption
• Process creation events originating from MSPUB.exe that spawn child processes such as cmd.exe, powershell.exe, or wscript.exe
• Network connections initiated by the Publisher process to unknown external IP addresses

Detection Strategies

• Monitor endpoint detection and response (EDR) alerts for suspicious behavior patterns from MSPUB.exe
• Implement email attachment scanning to detect potentially malicious Publisher documents
• Deploy application whitelisting to prevent unauthorized code execution from Office applications
• Configure security analytics to correlate document opening events with subsequent suspicious process activity

Monitoring Recommendations

• Enable enhanced logging for Microsoft Office applications to capture document processing events
• Monitor for anomalous child process creation from Publisher and other Office applications
• Implement file integrity monitoring for Office application directories
• Establish baseline behavior for Office applications to detect deviations indicative of exploitation

How to Mitigate CVE-2023-28287

Immediate Actions Required

• Apply Microsoft security updates immediately to all affected systems running Microsoft Publisher
• Restrict opening Publisher files from untrusted sources through Group Policy or security awareness training
• Enable Protected View in Microsoft Office to open documents from the internet in a sandboxed environment
• Consider temporarily blocking .pub file attachments at the email gateway if immediate patching is not possible

Patch Information

Microsoft has released security updates to address this vulnerability. Organizations should apply the latest cumulative updates for Microsoft Office products. The official security advisory from Microsoft provides detailed patching guidance and is available at the Microsoft Security Response Center.

For enterprises using Microsoft 365 Apps, ensure automatic updates are enabled and functioning properly. For standalone versions of Microsoft Publisher 2013 SP1 and Publisher 2016, apply the appropriate security updates from Windows Update or the Microsoft Update Catalog.

Workarounds

• Enable Protected View for files originating from the Internet in Microsoft Office Trust Center settings
• Configure Microsoft Office to open documents in Protected View for all untrusted locations
• Implement strict email filtering policies to quarantine Publisher document attachments pending security review
• Deploy application control policies to prevent Office applications from launching unauthorized child processes

# PowerShell: Enable Protected View for files from Internet
# Run with administrative privileges
Set-ItemProperty -Path "HKCU:\SOFTWARE\Microsoft\Office\16.0\Publisher\Security\ProtectedView" -Name "DisableInternetFilesInPV" -Value 0 -Type DWord
Set-ItemProperty -Path "HKCU:\SOFTWARE\Microsoft\Office\16.0\Publisher\Security\ProtectedView" -Name "DisableAttachementsInPV" -Value 0 -Type DWord
Set-ItemProperty -Path "HKCU:\SOFTWARE\Microsoft\Office\16.0\Publisher\Security\ProtectedView" -Name "DisableUnsafeLocationsInPV" -Value 0 -Type DWord