CVE-2020-5633
📋 TL;DR
This critical vulnerability in NEC server BMC firmware allows remote attackers to bypass authentication entirely. Attackers can then access/modify BMC settings, obtain monitoring data, or reboot/shutdown affected servers. All organizations using specified NEC Express5800 and iStorage products with vulnerable BMC firmware are affected.
💻 Affected Systems
- Express5800/T110j
- Express5800/T110j-S
- Express5800/T110j (2nd-Gen)
- Express5800/T110j-S (2nd-Gen)
- iStorage NS100Ti
- Express5800/GT110j
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of server management interface allowing attackers to modify hardware settings, exfiltrate monitoring data, and cause denial of service through forced reboots or shutdowns.
Likely Case
Unauthorized access to server management interface leading to configuration changes, monitoring data theft, and potential service disruption.
If Mitigated
Limited impact if BMC interfaces are properly segmented and access-controlled, though authentication bypass remains a serious concern.
🎯 Exploit Status
Authentication bypass via unspecified vectors suggests relatively straightforward exploitation once vectors are identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: BMC firmware Rev1.10 or later
Vendor Advisory: https://jpn.nec.com/security-info/secinfo/nv21-002.html
Restart Required: Yes
Instructions:
1. Download updated BMC firmware from NEC support site. 2. Backup current BMC configuration. 3. Apply firmware update via BMC web interface or management tools. 4. Reboot server to complete installation. 5. Verify firmware version is Rev1.10 or later.
🔧 Temporary Workarounds
Network Segmentation
allIsolate BMC management interfaces from untrusted networks using firewalls or VLANs
Access Control Lists
allRestrict access to BMC IP addresses to only authorized management systems
🧯 If You Can't Patch
- Segment BMC management interfaces completely from production networks
- Implement strict network access controls allowing only trusted IP addresses to connect to BMC interfaces
🔍 How to Verify
Check if Vulnerable:
Check BMC firmware version via web interface (System Information) or IPMI tools. If version is Rev1.09 or earlier, system is vulnerable.Check Version:
ipmitool mc info (Linux) or check via BMC web interface at https://[BMC_IP]Verify Fix Applied:
Confirm BMC firmware version is Rev1.10 or later through web interface or management console.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts followed by successful access
- Unauthorized configuration changes in BMC logs
- Unexpected reboots or shutdown commands
Network Indicators:
- Unusual traffic to BMC management ports (typically 443, 623, 5900)
- Authentication bypass attempts to BMC web interface
SIEM Query:
source="BMC" AND (event_type="authentication" AND result="success" AND user="unknown") OR (event_type="system" AND action="reboot" OR action="shutdown")🔗 References
- https://jpn.nec.com/security-info/secinfo/nv21-002.html
- https://jvn.jp/en/jp/JVN38752718/index.html
- https://www.support.nec.co.jp/View.aspx?id=9010108754
- https://jpn.nec.com/security-info/secinfo/nv21-002.html
- https://jvn.jp/en/jp/JVN38752718/index.html
- https://www.support.nec.co.jp/View.aspx?id=9010108754
