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CVE-2018-8327

9.8 CRITICAL
Remote Code Execution

📋 TL;DR

A remote code execution vulnerability in PowerShell Editor Services allows attackers to execute arbitrary code on affected systems. This affects users of PowerShell Editor and PowerShell Extension in vulnerable configurations. Attackers can potentially take full control of the system.

💻 Affected Systems

Products:
  • PowerShell Editor Services
  • PowerShell Editor
  • PowerShell Extension
Versions: Versions prior to the security update released in July 2018
Operating Systems: Windows, Linux, macOS (where PowerShell Editor Services is installed)
Default Config Vulnerable: ⚠️ Yes
Notes: Affects systems where PowerShell Editor Services is installed and accessible to attackers.

📦 What is this software?

Powershell by Microsoft

View all CVEs affecting Powershell →

Powershell Editor Services by Microsoft

View all CVEs affecting Powershell Editor Services →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise with administrative privileges, data theft, lateral movement, and persistent backdoor installation.

🟠

Likely Case

Unauthorized code execution leading to credential harvesting, data exfiltration, or ransomware deployment.

🟢

If Mitigated

Limited impact due to network segmentation, least privilege, and monitoring controls.

🌐 Internet-Facing: HIGH if PowerShell Editor Services is exposed to untrusted networks.
🏢 Internal Only: HIGH due to potential lateral movement and privilege escalation within networks.

🎯 Exploit Status

Public PoC: ⚠️ Yes
Weaponized: LIKELY
Unauthenticated Exploit: ⚠️ Yes
Complexity: LOW

Exploitation details have been publicly disclosed, making attacks easier to execute.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Update to the latest version of PowerShell Editor Services (post-July 2018 security update)

Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8327

Restart Required: Yes

Instructions:

1. Update PowerShell Editor Services through your package manager or extension marketplace. 2. Restart any PowerShell Editor Services processes. 3. Verify the update was applied successfully.

🔧 Temporary Workarounds

Disable PowerShell Editor Services

all

Temporarily disable PowerShell Editor Services if not required.

# For PowerShell Extension in VS Code: Disable the extension
# For standalone: Stop the PowerShell Editor Services process

Network Segmentation

all

Restrict network access to PowerShell Editor Services ports.

# Use firewall rules to block inbound connections to PowerShell Editor Services ports
# Example Windows: New-NetFirewallRule -DisplayName 'Block PSES' -Direction Inbound -LocalPort <port> -Protocol TCP -Action Block

🧯 If You Can't Patch

  • Implement strict network access controls to limit exposure.
  • Apply the principle of least privilege to user accounts and service permissions.

🔍 How to Verify

Check if Vulnerable:

Check the version of PowerShell Editor Services installed. If it's from before July 2018, it's likely vulnerable.

Check Version:

# In PowerShell: Get-Module -Name PowerShellEditorServices -ListAvailable | Select-Object Version

Verify Fix Applied:

Verify the version is updated to a post-July 2018 release and test functionality.

📡 Detection & Monitoring

Log Indicators:

  • Unusual process creation from PowerShell Editor Services
  • Suspicious network connections from PowerShell Editor Services

Network Indicators:

  • Unexpected inbound connections to PowerShell Editor Services ports
  • Anomalous outbound traffic from affected systems

SIEM Query:

Example: Process creation where parent process contains 'PowerShellEditorServices' AND command line contains suspicious patterns

📊 Metadata

CVE ID: CVE-2018-8327
CVSS v3 Score: 9.8 (CRITICAL)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: July 11, 2018
Last Updated: July 16, 2025

🔗 References

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