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A critical security flaw in Microsoft’s OneDrive File Picker allows third-party apps—including AI chatbots like ChatGPT—to gain full read access to a user’s entire OneDrive storage after a single file upload. Researchers from Oasis Security discovered that hundreds of apps, including Slack, Trello, and ClickUp, retain this access indefinitely, posing severe risks of data leaks and compliance violations.
Microsoft has acknowledged the issue and is working on improvements, but users and admins must take immediate action to review and revoke unnecessary third-party access.
Source: CyberNews
You Should Know: How to Secure Your OneDrive and Mitigate Risks
1. Review and Revoke Third-Party Access
Windows Command (PowerShell):
List all apps with access to your OneDrive Get-MgOauth2PermissionGrant | Select-Object ClientId, Scope, ConsentType
Steps:
2. Remove suspicious or unused apps.
2. Monitor Suspicious Activity
Linux Command (Audit OneDrive Sync Logs):
Check OneDrive sync logs (Linux/WSL) grep -i "error|warning" ~/.local/share/onedrive/logs/onedrive.log
3. Restrict Access via Conditional Access Policies (Admins)
Azure AD PowerShell:
Block third-party apps from accessing OneDrive
New-MgConditionalAccessPolicy -DisplayName "Block OneDrive Risky Apps" -State "enabled" -Conditions @{ Applications = @{ IncludeApplications = "Microsoft.OneDrive" } } -GrantControls @{ Operator = "OR"; BuiltInControls = "block" }
4. Encrypt Sensitive Files Before Uploading
Linux (GPG Encryption):
Encrypt a file before uploading gpg --encrypt --recipient '[email protected]' sensitive_document.pdf
5. Disable OneDrive File Picker (Temporary Fix)
Registry Edit (Windows):
Disable OneDrive integration in File Explorer reg add "HKLM\Software\Policies\Microsoft\Windows\OneDrive" /v "DisableFileSyncNGSC" /t REG_DWORD /d 1 /f
What Undercode Say
This vulnerability highlights the dangers of over-permissive cloud integrations. While Microsoft works on a fix, users must:
– Audit permissions regularly.
– Use encryption for sensitive files.
– Adopt Zero Trust principles for cloud storage.
Future-proofing: Expect stricter OAuth scopes and AI-driven access controls in cloud services.
Expected Output:
- Mitigation: Revoke unnecessary app access.
- Detection: Monitor sync logs for anomalies.
- Prevention: Encrypt files before sharing.
Prediction
Microsoft will likely enforce granular OAuth permissions and introduce AI-based anomaly detection for OneDrive access patterns within the next 6 months.
Relevant Commands Recap:
Check app permissions Get-MgOauth2PermissionGrant Block risky apps in Azure AD New-MgConditionalAccessPolicy -DisplayName "Restrict OneDrive Apps" -State "enabled"
Encrypt files before upload gpg --encrypt --recipient '[email protected]' file.txt
IT/Security Reporter URL:
Reported By: Michael Tchuindjang – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
