CVE-2021-45970
📋 TL;DR
This vulnerability in Insyde InsydeH2O firmware's System Management Mode (SMM) allows attackers with local access to execute arbitrary code with SMM privileges by exploiting insufficient buffer pointer validation in the IdeBusDxe driver. It affects systems running InsydeH2O kernel versions 5.1 through 5.5 before specific patch versions. Successful exploitation could lead to complete system compromise.
💻 Affected Systems
- Insyde InsydeH2O firmware with IdeBusDxe driver
📦 What is this software?
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with SMM privileges, allowing persistent malware installation, firmware modification, and bypassing all OS-level security controls.
Likely Case
Local privilege escalation to SMM level, enabling attackers to install persistent backdoors, intercept sensitive data, or disable security features.
If Mitigated
Limited impact if proper access controls prevent local attacker access and SMM protections are enforced.
🎯 Exploit Status
Requires local access and SMM exploitation knowledge. No public exploit code available as of knowledge cutoff.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel 5.1: 05.16.25+, 5.2: 05.26.25+, 5.3: 05.35.25+, 5.4: 05.43.25+, 5.5: 05.51.25+
Vendor Advisory: https://www.insyde.com/security-pledge
Restart Required: Yes
Instructions:
1. Contact system/OEM vendor for firmware update. 2. Download appropriate firmware version for your hardware. 3. Follow vendor's firmware update procedure. 4. Reboot system to apply update.
🔧 Temporary Workarounds
Restrict local access
allLimit physical and administrative access to vulnerable systems to reduce attack surface.
Enable SMM protection features
allConfigure BIOS/UEFI settings to enable SMM protection if available in your system.
🧯 If You Can't Patch
- Isolate affected systems from critical networks and limit user access
- Implement strict endpoint security monitoring for SMM-related anomalies
🔍 How to Verify
Check if Vulnerable:
Check firmware version in BIOS/UEFI settings or using manufacturer-specific tools. Compare against affected version ranges.Check Version:
System-specific: Check BIOS/UEFI version during boot or use manufacturer diagnostic toolsVerify Fix Applied:
Verify firmware version has been updated to patched versions listed in fix_official section.📡 Detection & Monitoring
Log Indicators:
- Unexpected SMM handler calls
- Firmware modification attempts
- Privilege escalation patterns
Network Indicators:
- None - local exploitation only
SIEM Query:
Endpoint logs showing unusual SMM access or firmware modification attempts🔗 References
- https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
- https://security.netapp.com/advisory/ntap-20220216-0004/
- https://www.insyde.com/security-pledge
- https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
- https://security.netapp.com/advisory/ntap-20220216-0004/
- https://www.insyde.com/security-pledge
- https://www.kb.cert.org/vuls/id/796611
