CVE-2023-24955
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on Microsoft SharePoint Server by sending specially crafted requests. It affects organizations running vulnerable SharePoint Server versions, potentially enabling complete system compromise.
💻 Affected Systems
- Microsoft SharePoint Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise leading to data theft, ransomware deployment, lateral movement across network, and persistent backdoor installation.
Likely Case
Unauthorized access to SharePoint data, privilege escalation, and installation of web shells for ongoing access.
If Mitigated
Limited impact with proper network segmentation, application firewalls, and least privilege configurations in place.
🎯 Exploit Status
Exploitation requires authentication, but standard user credentials may be sufficient. Microsoft rates this as 'Exploitation More Likely'.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft's monthly security updates for specific patch versions
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-24955
Restart Required: Yes
Instructions:
1. Apply latest Microsoft security updates for SharePoint Server. 2. Restart SharePoint services. 3. Test functionality after patching.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to SharePoint servers using firewalls
Authentication Hardening
allImplement multi-factor authentication and strong password policies
🧯 If You Can't Patch
- Isolate SharePoint servers in separate network segments with strict firewall rules
- Implement web application firewall (WAF) with SharePoint-specific rules
🔍 How to Verify
Check if Vulnerable:
Check SharePoint Server version against Microsoft's security bulletin for affected versionsCheck Version:
Get-SPFarm | Select BuildVersion (PowerShell on SharePoint server)Verify Fix Applied:
Verify SharePoint Server version matches or exceeds patched version in Microsoft advisory📡 Detection & Monitoring
Log Indicators:
- Unusual authentication patterns
- Suspicious file uploads to SharePoint
- Unexpected process execution
Network Indicators:
- Unusual outbound connections from SharePoint servers
- Suspicious HTTP requests to SharePoint endpoints
SIEM Query:
source="sharepoint" AND (event_id=6398 OR event_id=6399) AND (process_execution OR file_upload)