CVE-2020-16948
📋 TL;DR
This CVE describes an information disclosure vulnerability in Microsoft SharePoint Server where improper memory handling allows authenticated attackers to access sensitive information. The vulnerability requires an attacker to have valid login credentials and run a specially crafted application on the affected system. Organizations using vulnerable SharePoint Server versions are at risk of data exposure.
💻 Affected Systems
- Microsoft SharePoint Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An authenticated attacker could access sensitive SharePoint data, user credentials, or configuration information, leading to further system compromise or data exfiltration.
Likely Case
An authenticated malicious insider or compromised account could access confidential documents, user information, or system configuration data.
If Mitigated
With proper access controls, monitoring, and network segmentation, the impact is limited to authorized users accessing data they shouldn't see.
🎯 Exploit Status
Exploitation requires authenticated access and ability to run crafted applications on the SharePoint server
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update for specific patch version
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16948
Restart Required: Yes
Instructions:
1. Review Microsoft Security Advisory CVE-2020-16948
2. Download and apply the appropriate security update from Microsoft Update Catalog
3. Restart SharePoint Server services or the entire server as required
4. Test SharePoint functionality after patching
🔧 Temporary Workarounds
Restrict User Access
allLimit SharePoint access to only necessary users and implement least privilege principles
Application Control
windowsImplement application whitelisting to prevent execution of unauthorized applications on SharePoint servers
🧯 If You Can't Patch
- Implement strict access controls and monitor for unusual authenticated user activity
- Segment SharePoint servers from other critical systems to limit lateral movement potential
🔍 How to Verify
Check if Vulnerable:
Check SharePoint Server version and compare against Microsoft's patched versions listCheck Version:
Get-SPFarm | Select BuildVersion (PowerShell on SharePoint Server)Verify Fix Applied:
Verify SharePoint Server version matches or exceeds patched version from Microsoft advisory📡 Detection & Monitoring
Log Indicators:
- Unusual authenticated user activity patterns
- Multiple failed authentication attempts followed by successful login
- Unexpected process execution on SharePoint servers
Network Indicators:
- Unusual outbound data transfers from SharePoint servers
- Anomalous authenticated user behavior patterns
SIEM Query:
source="SharePoint" AND (event_type="Process Creation" OR event_type="File Access") AND user!="SYSTEM" AND user!="NETWORK SERVICE"