CVE-2020-16950
📋 TL;DR
This CVE describes an information disclosure vulnerability in Microsoft SharePoint Server where improper memory handling could allow an authenticated attacker to access sensitive information. The vulnerability requires an attacker to have valid login credentials and the ability to run a crafted application on the affected system. Organizations running vulnerable SharePoint Server versions are affected.
💻 Affected Systems
- Microsoft SharePoint Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An authenticated attacker could access sensitive information from SharePoint Server memory, potentially obtaining credentials, configuration data, or other sensitive information that could lead to further system compromise.
Likely Case
An authenticated malicious insider or compromised account could extract limited information from memory, potentially gaining insights into system configuration or user data.
If Mitigated
With proper access controls and monitoring, the impact is limited to authorized users who would already have some level of access to the system.
🎯 Exploit Status
Exploitation requires authenticated access and ability to run crafted applications on the target system.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft's October 2020 security updates for SharePoint Server
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16950
Restart Required: Yes
Instructions:
1. Apply Microsoft's October 2020 security updates for SharePoint Server. 2. Restart affected SharePoint services or servers as required. 3. Verify the update was successfully applied.
🔧 Temporary Workarounds
Restrict application execution
windowsLimit ability to run arbitrary applications on SharePoint servers to authorized administrators only
Use Group Policy or AppLocker to restrict application execution
Enforce least privilege
allEnsure users only have necessary permissions and cannot run arbitrary applications
Review and tighten SharePoint permissions and local system access
🧯 If You Can't Patch
- Implement strict access controls to limit who can authenticate to SharePoint servers
- Monitor for unusual application execution or memory access patterns on SharePoint systems
🔍 How to Verify
Check if Vulnerable:
Check SharePoint Server version against Microsoft's advisory; vulnerable if running unpatched versions from before October 2020Check Version:
Get-SPFarm | Select BuildVersion (PowerShell) or check Central Administration > Upgrade and Migration > Check product and patch installation statusVerify Fix Applied:
Verify SharePoint Server has October 2020 or later security updates installed📡 Detection & Monitoring
Log Indicators:
- Unusual application execution on SharePoint servers
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unusual outbound data transfers from SharePoint servers
SIEM Query:
source="SharePoint" AND (event_id=4688 OR process_execution) AND user NOT IN (authorized_admin_users)