Microsoft Office Equation Editor Memory Corruption Remote Code Execution Vulnerability (CVE-2018-0798)
Executive & SecOps Summary
SECOPS ASSESSMENTEquation Editor (EQNEDT32.EXE) component included in Microsoft Office 2007, 2010, 2013, and 2016
Remote attackers can execute arbitrary code with the privileges of the logged-in user by tricking them into opening a specially crafted Office document containing malicious OLE objects
Apply official Microsoft security patches immediately, or disable the legacy Equation Editor component via registry modifications
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to apply the official security updates provided by Microsoft. Run the following PowerShell commands to force-install pending Office security updates:
# Install Windows Update module and apply pending Microsoft Office security patches
Install-Module PSWindowsUpdate -Force -Verbose
Get-WindowsUpdate -Category 'Security Updates' -AcceptAll -Install -AutoReboot2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, disable the Equation Editor 3.0 COM object by setting the compatibility flags (Kill Bit) in the Windows Registry:
# Disable Equation Editor 3.0 COM object via Registry to prevent execution
reg add 'HKLM\SOFTWARE\Microsoft\Office\Common\COM Compatibility\{0002CE02-0000-0000-C000-000000000046}' /v 'Compatibility Flags' /t REG_DWORD /d 0x00000400 /f
reg add 'HKLM\SOFTWARE\Wow6432Node\Microsoft\Office\Common\COM Compatibility\{0002CE02-0000-0000-C000-000000000046}' /v 'Compatibility Flags' /t REG_DWORD /d 0x00000400 /f3. Log Audit & IoC Verification Commands
Verify the presence of the vulnerable EQNEDT32.EXE binary on the system and inspect process creation logs for anomalous child processes spawned by it:
# Locate the EQNEDT32.EXE binary on the local system
Get-ChildItem -Path 'C:\Program Files*\Common Files\Microsoft Shared\EQUATION' -Filter 'EQNEDT32.EXE' -Recurse -ErrorAction SilentlyContinue | Select-Object FullName, Length, LastWriteTimeBlock Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability is a stack-based buffer overflow (CWE-787) in the legacy Equation Editor ('EQNEDT32.EXE') component of Microsoft Office. Due to improper validation of input length when parsing MTEF (MathType Equation Format) data within OLE objects, the application copies excessive data into a fixed-size stack buffer, leading to memory corruption.
2. Exploitation Mechanics & Attack Scenario
An attacker crafts a malicious document (typically RTF or DOCX) containing a malformed Equation Editor object. When a user opens the document, Microsoft Office spawns the legacy EQNEDT32.EXE process to render the equation. The malformed input triggers a buffer overflow, overwriting the return address on the stack and redirecting execution flow to the attacker's shellcode, bypassing modern mitigations due to the legacy nature of the binary.
3. Infrastructure & Business Impact
As a CISA KEV-listed vulnerability with a high EPSS score, this flaw is actively exploited in the wild by advanced persistent threat (APT) actors for initial access. Successful exploitation grants the attacker full control over the victim's endpoint, potentially leading to lateral movement, ransomware deployment, and sensitive data exfiltration.
Official Vendor Advisories & References
Equation Editor in Microsoft Office 2007, Microsoft Office 2010, Microsoft Office 2013, and Microsoft Office 2016 allows a remote code execution vulnerability due to the way objects are handled in memory, aka "Microsoft Office Memory Corruption Vulnerability".
Frequently Asked SecOps Questions (CVE-2018-0798)
FAQQ1. How critical is CVE-2018-0798 and is it actively exploited in the wild?
CVE-2018-0798 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 95.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2018-0798?
Primary impacted vendors include microsoft across office, equation_editor. Scope summary: Microsoft Office 2007, 2010, 2013, 2016 and the legacy Equation Editor (EQNEDT32.EXE) component
Q3. What temporary mitigations or workarounds exist for CVE-2018-0798 before patching?
[Mitigation] Apply official Microsoft security patches immediately, or disable the legacy Equation Editor component via registry modifications Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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