Security News > 2024 > April > Microsoft pulls fix for Outlook bug behind ICS security alerts
Microsoft has rolled back a fix for a known Outlook issue that was causing incorrect security alerts when opening ICS calendar files after installing the December Outlook Desktop security updates.
Affected Microsoft 365 users are seeing unexpected warnings that "Microsoft Office has identified a potential security concern" and that "This location may be unsafe" when double-clicking ICS files saved on their devices.
The December security updates triggering these alerts patch an Outlook information disclosure vulnerability that can let attackers steal NTLM hashes via maliciously crafted files and use them in Windows pass-the-hash attacks to access sensitive data or move laterally on the network.
Microsoft fixed the issue in early April and started shipping it with Outlook for Microsoft 365 Version 2404 Build 17531.
Microsoft fixes Outlook security alerts bug caused by December updates.
Microsoft warns Gmail blocks some Outlook email as spam, shares fix.
News URL
Related news
- URGENT: Microsoft Patches 57 Security Flaws, Including 6 Actively Exploited Zero-Days (source)
- Patch Tuesday: Microsoft Fixes 57 Security Flaws – Including Active Zero-Days (source)
- Microsoft says button to restore classic Outlook is broken (source)
- Microsoft Exchange Online outage affects Outlook web users (source)
- AI agents swarm Microsoft Security Copilot (source)
- After Detecting 30B Phishing Attempts, Microsoft Adds Even More AI to Its Security Copilot (source)
- Android Malware Exploits a Microsoft-Related Security Blind Spot to Avoid Detection (source)
- Microsoft fixes button that restores classic Outlook client (source)
- Week in review: Chrome sandbox escape 0-day fixed, Microsoft adds new AI agents to Security Copilot (source)
- April 2025 Patch Tuesday forecast: More AI security introduced by Microsoft (source)