CVE-2025-62204
📋 TL;DR
This vulnerability allows an authenticated attacker to execute arbitrary code on Microsoft SharePoint servers by sending specially crafted deserialized data. It affects organizations running vulnerable SharePoint versions, requiring the attacker to have valid credentials but enabling remote code execution.
💻 Affected Systems
- Microsoft SharePoint Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise leading to data theft, lateral movement, ransomware deployment, or complete SharePoint environment takeover.
Likely Case
Attacker gains persistent access to SharePoint server, exfiltrates sensitive documents, and potentially moves to other internal systems.
If Mitigated
Attack blocked at network perimeter or detected before code execution; limited to failed authentication attempts.
🎯 Exploit Status
Requires authenticated access and understanding of SharePoint deserialization mechanisms; no public exploit available yet.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update for specific version
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-62204
Restart Required: Yes
Instructions:
1. Review Microsoft advisory for affected versions. 2. Apply the latest security update through Windows Update or Microsoft Update Catalog. 3. Restart SharePoint servers after patching. 4. Test functionality post-patch.
🔧 Temporary Workarounds
Restrict network access
allLimit SharePoint server access to trusted IP ranges only.
Configure firewall rules to allow only necessary IP addresses to SharePoint ports (typically 80, 443).
Implement application controls
windowsUse application whitelisting to prevent execution of unauthorized code.
Configure Windows Defender Application Control or similar to allow only signed SharePoint binaries.
🧯 If You Can't Patch
- Segment SharePoint servers from critical networks using firewalls/VLANs.
- Implement strict authentication monitoring and alert on suspicious authenticated sessions.
🔍 How to Verify
Check if Vulnerable:
Check SharePoint version against Microsoft advisory; if running affected version and not patched, assume vulnerable.Check Version:
Get-SPFarm | Select BuildVersion (PowerShell on SharePoint server)Verify Fix Applied:
Verify SharePoint version matches patched version in Microsoft advisory and restart has been performed.📡 Detection & Monitoring
Log Indicators:
- Unusual deserialization errors in SharePoint logs
- Unexpected process creation from SharePoint worker processes
- Authentication logs showing suspicious user access patterns
Network Indicators:
- Anomalous network traffic from SharePoint servers to external IPs
- Unexpected outbound connections following authentication events
SIEM Query:
source="sharepoint_logs" AND (event_id="deserialization_error" OR process_name="powershell.exe" OR cmdline="*Invoke-Expression*")