CVE-2025-59258
📋 TL;DR
This vulnerability in Active Directory Federation Services (AD FS) allows unauthorized local attackers to read sensitive information from log files. It affects organizations using AD FS for identity federation. The issue involves improper logging of sensitive data that could be accessed by local users.
💻 Affected Systems
- Active Directory Federation Services
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain access to sensitive authentication tokens, credentials, or configuration details that could enable further attacks against federated identity systems.
Likely Case
Local users with access to log files can extract sensitive information that should not be exposed, potentially compromising security boundaries.
If Mitigated
With proper access controls and log file permissions, the impact is limited to authorized administrators only.
🎯 Exploit Status
Requires local access to the AD FS server and ability to read log files. No authentication bypass needed if local access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update for exact version
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-59258
Restart Required: No
Instructions:
1. Apply the latest Microsoft security update for AD FS. 2. Verify the patch is installed. 3. Review and adjust logging configurations if necessary.
🔧 Temporary Workarounds
Restrict log file access
windowsApply strict permissions to AD FS log directories to prevent unauthorized access
icacls "C:\ADFS\Logs" /inheritance:r /grant "Administrators:(OI)(CI)F" /grant "SYSTEM:(OI)(CI)F"
Review and adjust logging configuration
windowsConfigure AD FS to avoid logging sensitive information
Review AD FS audit and diagnostic logging settings in AD FS Management console
🧯 If You Can't Patch
- Implement strict access controls on AD FS servers to limit local user access
- Regularly monitor and review AD FS log files for sensitive information exposure
🔍 How to Verify
Check if Vulnerable:
Check AD FS version against Microsoft's advisory and review log files for sensitive dataCheck Version:
Get-AdfsProperties | Select-Object -Property ProductVersionVerify Fix Applied:
Verify patch installation via Windows Update history and check that sensitive data is no longer logged📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts to AD FS log files
- Sensitive data patterns in AD FS logs
Network Indicators:
- Unusual local file access patterns on AD FS servers
SIEM Query:
EventID=4663 AND ObjectName LIKE '%ADFS%Logs%' AND AccessMask=0x1