CVE-2020-5353
📋 TL;DR
This vulnerability allows attackers to spoof their UID over NFS to gain write access to the admin home directory on affected Dell Isilon/PowerScale systems. Attackers can rewrite sensitive files to escalate privileges and gain administrative control. Organizations using Dell Isilon OneFS versions 8.2.2 and earlier or Dell EMC PowerScale OneFS version 9.0.0 with NFS enabled are affected.
💻 Affected Systems
- Dell Isilon OneFS
- Dell EMC PowerScale OneFS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full administrative compromise of the storage system, allowing data theft, destruction, or ransomware deployment across connected systems.
Likely Case
Privilege escalation leading to unauthorized administrative access, configuration changes, and potential data exfiltration.
If Mitigated
Limited impact with proper network segmentation, NFS access controls, and monitoring in place.
🎯 Exploit Status
Exploitation requires NFS access and ability to spoof UID, which is relatively straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: OneFS 8.2.2.1 and later, PowerScale OneFS 9.0.0.1 and later
Vendor Advisory: https://support.emc.com/kb/542721
Restart Required: Yes
Instructions:
1. Download the appropriate patch from Dell EMC support. 2. Apply the patch following Dell's upgrade procedures. 3. Reboot the system as required. 4. Verify the patch is applied successfully.
🔧 Temporary Workarounds
Disable NFS if not needed
linuxCompletely disable NFS services on affected systems if they are not required for operations.
isi nfs disable
Restrict NFS access
linuxConfigure NFS export rules to limit access to trusted networks and clients only.
isi nfs exports modify --zone=<zone> --client=<trusted_client>
🧯 If You Can't Patch
- Implement strict network segmentation to isolate NFS traffic to trusted networks only
- Deploy host-based firewalls to restrict NFS access to authorized IP addresses
🔍 How to Verify
Check if Vulnerable:
Check if running OneFS 8.2.2 or earlier, or PowerScale OneFS 9.0.0 with NFS enabled. Use: isi versionCheck Version:
isi versionVerify Fix Applied:
Verify version is 8.2.2.1+ or 9.0.0.1+ and check NFS configuration for proper access controls.📡 Detection & Monitoring
Log Indicators:
- Unusual NFS access patterns
- UID spoofing attempts in NFS logs
- Unauthorized file modifications in admin directories
Network Indicators:
- Unexpected NFS traffic from unauthorized sources
- UID manipulation attempts over NFS
SIEM Query:
source="nfs_logs" AND (event="unauthorized_access" OR uid="0" OR uid="admin")