CVE-2021-39987
📋 TL;DR
CVE-2021-39987 is a data processing error vulnerability in the HwNearbyMain module of HarmonyOS devices. Successful exploitation can cause process restarts, potentially disrupting device functionality. This affects Huawei/Honor devices running vulnerable versions of HarmonyOS.
💻 Affected Systems
- Huawei/Honor devices with HarmonyOS
📦 What is this software?
Harmonyos by Huawei
⚠️ Risk & Real-World Impact
Worst Case
Denial of service through repeated process crashes, potentially affecting device stability and availability of nearby services functionality.
Likely Case
Temporary service disruption causing the affected process to restart, with possible impact on nearby device discovery and connectivity features.
If Mitigated
Minimal impact with proper patching; process restart may cause brief service interruption but no persistent damage.
🎯 Exploit Status
Exploitation likely requires local access or malicious app installation. No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: HarmonyOS November 2021 security update and later
Vendor Advisory: https://device.harmonyos.com/en/docs/security/update/security-bulletins-202111-0000001217889667
Restart Required: Yes
Instructions:
1. Check for system updates in device Settings > System & updates > Software update. 2. Install the November 2021 or later security update. 3. Restart device after installation completes.
🔧 Temporary Workarounds
Disable Nearby Services
allTemporarily disable the HwNearbyMain module functionality to prevent exploitation
Settings > More connections > Nearby sharing > Turn off
🧯 If You Can't Patch
- Restrict installation of untrusted applications to reduce attack surface
- Implement network segmentation to limit lateral movement if device is compromised
🔍 How to Verify
Check if Vulnerable:
Check HarmonyOS version in Settings > About phone > HarmonyOS version. If version is prior to November 2021 security update, device is vulnerable.Check Version:
Settings > About phone > HarmonyOS versionVerify Fix Applied:
Verify HarmonyOS version is November 2021 security update or later in Settings > About phone > HarmonyOS version.📡 Detection & Monitoring
Log Indicators:
- Repeated crashes/restarts of HwNearbyMain process
- Abnormal termination logs for nearby services
Network Indicators:
- Unusual nearby device discovery attempts
- Abnormal Bluetooth/Wi-Fi Direct activity patterns
SIEM Query:
Process termination events for HwNearbyMain with abnormal exit codes