Microsoft Office OLE Composite Moniker Remote Code Execution Vulnerability (CVE-2017-8570) Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Office 2007, 2010, 2013, 2016 and related productivity components
Remote attackers can execute arbitrary code with the privileges of the current user via crafted Office documents containing malicious OLE objects
Apply official Microsoft security patches immediately and restrict the execution of untrusted OLE/ActiveX components
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official security updates provided by Microsoft. In enterprise environments, administrators can use the following PowerShell commands to audit and install the required security updates.
# Install Windows Update module and force installation of relevant KB patches
Install-Module PSWindowsUpdate -Force -SkipPublisherCheck
Get-WindowsUpdate -KBArticleID KB4011039, KB4011052, KB4011075 -Install -AcceptAll -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, you can mitigate the risk by disabling the Packager ActiveX control via the Windows Registry to prevent the execution of embedded OLE packages.
:: Disable Packager ActiveX controls to mitigate OLE-based exploitation
reg add 'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\16.0\Common\Security' /v 'DisablePackagerActiveX' /t REG_DWORD /d 1 /f
reg add 'HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\16.0\Common\Security' /v 'DisablePackagerActiveX' /t REG_DWORD /d 1 /f3. Log Audit & IoC Verification Commands
Use the following PowerShell script to scan the system's temporary directories for suspicious .sct files, which are commonly dropped during CVE-2017-8570 exploitation attempts.
# Scan for suspicious scriptlet (.sct) files in the user temp directory
$TempPath = [System.IO.Path]::GetTempPath()
$SuspiciousFiles = Get-ChildItem -Path $TempPath -Filter '*.sct' -Recurse -ErrorAction SilentlyContinue
if ($SuspiciousFiles) {
Write-Host '[WARNING] Potential IoC detected! Suspicious .sct files found:' -ForegroundColor Red
$SuspiciousFiles | Select-Object FullName, CreationTime
} else {
Write-Host '[INFO] No suspicious .sct files found in the temp directory.' -ForegroundColor Green
}Block 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 (CVE-2017-8570) is a remote code execution (RCE) vulnerability that exists in Microsoft Office due to the improper handling of OLE (Object Linking and Embedding) objects in memory. Specifically, the root cause lies in how Office parses and resolves Composite Monikers. By failing to properly validate input when resolving these monikers, the application can be coerced into executing arbitrary scriptlet files (.sct) hosted locally or remotely, bypassing standard security boundaries.
2. Exploitation Mechanics & Attack Scenario
An attacker exploits this vulnerability by crafting a malicious Office document, such as a PowerPoint Show (.ppsx) or Word (.docx) file, containing a specially designed OLE object. The attacker modifies the document's internal XML relationships to point to a Composite Moniker that references a malicious Scriptlet (SCT) file. When a victim opens the document, the Office application automatically triggers the OLE activation process, resolves the moniker, and executes the payload within the SCT file via COM interfaces or system utilities like regsvr32.exe without requiring user interaction beyond opening the file.
3. Infrastructure & Business Impact
As a high-severity vulnerability listed in the CISA KEV catalog, CVE-2017-8570 has been actively exploited in the wild by advanced persistent threat (APT) groups. Successful exploitation grants the attacker the same privileges as the logged-in user. This can lead to complete endpoint compromise, lateral movement within the corporate network, data exfiltration, and deployment of ransomware, posing a severe threat to business continuity.
Official Vendor Advisories & References
Microsoft Office allows a remote code execution vulnerability due to the way that it handles objects in memory, aka "Microsoft Office Remote Code Execution Vulnerability". This CVE ID is unique from CVE-2017-0243.
Frequently Asked SecOps Questions (CVE-2017-8570)
FAQQ1. How critical is CVE-2017-8570 and is it actively exploited in the wild?
CVE-2017-8570 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 89.9%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2017-8570?
Primary impacted vendors include microsoft across office, word, excel, powerpoint. Scope summary: Microsoft Office 2007 Service Pack 3, Microsoft Office 2010 Service Pack 2, Microsoft Office 2013 Service Pack 1, Microsoft Office 2016, and related compatibility packs
Q3. What temporary mitigations or workarounds exist for CVE-2017-8570 before patching?
[Mitigation] Apply official Microsoft security patches immediately and restrict the execution of untrusted OLE/ActiveX components Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2017-8570
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
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