CVE-2024-38149
📋 TL;DR
This vulnerability allows attackers to cause a denial of service (DoS) in BranchCache, a Windows feature that caches content from remote servers. Attackers can send specially crafted requests to BranchCache servers, causing them to stop responding. This affects Windows systems with BranchCache enabled, particularly servers and workstations in enterprise environments.
💻 Affected Systems
- Microsoft Windows
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 21h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of BranchCache functionality, potentially affecting content distribution and network performance in enterprise environments.
Likely Case
Temporary unavailability of BranchCache services requiring system restart to restore functionality.
If Mitigated
Minimal impact if BranchCache is disabled or systems are properly segmented.
🎯 Exploit Status
Microsoft rates this as 'Exploitation More Likely' in their advisory. The vulnerability can be exploited without authentication by sending specially crafted requests to BranchCache servers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: July 2024 security updates (KB5040434 for Windows 10, KB5040431 for Windows 11, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-38149
Restart Required: Yes
Instructions:
1. Apply the July 2024 Windows security updates from Windows Update. 2. Restart the system to complete the installation. 3. Verify the update is installed via Settings > Windows Update > Update history.
🔧 Temporary Workarounds
Disable BranchCache
windowsCompletely disable BranchCache service if not required
Disable-BC
sc config PeerDistSvc start= disabled
sc stop PeerDistSvc
Network Segmentation
allRestrict access to BranchCache ports (TCP 3702, 80, 443) to trusted hosts only
🧯 If You Can't Patch
- Disable BranchCache service on all vulnerable systems
- Implement network segmentation to restrict access to BranchCache servers to only trusted internal hosts
🔍 How to Verify
Check if Vulnerable:
Check if BranchCache is enabled: Run 'Get-BCStatus' in PowerShell. If enabled and system is unpatched, it's vulnerable.Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify July 2024 security updates are installed: Run 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version" /C:"Hotfix(s)"' and look for KB5040434 or similar July 2024 patches.📡 Detection & Monitoring
Log Indicators:
- Event ID 1000 in Application logs with faulting module PeerDistSvc.dll
- Sudden stoppage of BranchCache service logs
Network Indicators:
- Unusual traffic patterns to BranchCache ports (TCP 3702, 80, 443)
- Multiple connection attempts to BranchCache from single source
SIEM Query:
EventID=1000 AND SourceName="Application Error" AND FaultingModuleName="PeerDistSvc.dll"