CVE-2021-39992
📋 TL;DR
CVE-2021-39992 is an improper security permission configuration vulnerability in Huawei ACPU that allows attackers to bypass intended security restrictions. Successful exploitation could compromise service confidentiality, integrity, and availability. This affects Huawei devices running vulnerable versions of ACPU software.
💻 Affected Systems
- Huawei devices with ACPU
📦 What is this software?
Emui by Huawei
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing unauthorized access to sensitive data, service disruption, and potential lateral movement within the network.
Likely Case
Unauthorized access to restricted system functions, privilege escalation, and potential data exfiltration.
If Mitigated
Limited impact with proper access controls and network segmentation in place.
🎯 Exploit Status
Exploitation requires understanding of ACPU permission mechanisms; no public exploit code available based on provided references
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Huawei security update for specific device models
Vendor Advisory: https://consumer.huawei.com/en/support/bulletin/2022/2/
Restart Required: Yes
Instructions:
1. Check Huawei security bulletin for affected devices. 2. Apply latest security updates from Huawei. 3. Reboot device after update installation.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected devices from critical networks to limit potential damage
Access Control Restrictions
allImplement strict access controls and principle of least privilege
🧯 If You Can't Patch
- Isolate affected systems in separate network segments with strict firewall rules
- Implement additional monitoring and logging for suspicious ACPU-related activities
🔍 How to Verify
Check if Vulnerable:
Check device model and software version against Huawei security bulletin; verify if running vulnerable ACPU versionCheck Version:
Device-specific; typically in Settings > About Phone > Software Information on Huawei devicesVerify Fix Applied:
Confirm installation of latest security updates from Huawei; verify version number matches patched version in advisory📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts to ACPU services
- Permission escalation events
- Abnormal system calls related to security permissions
Network Indicators:
- Unusual network traffic from affected devices
- Attempts to access restricted ACPU endpoints
SIEM Query:
Search for events related to ACPU permission changes or unauthorized access attempts on Huawei devices