CVE-2021-40148
📋 TL;DR
This vulnerability in MediaTek modem EMM (Evolved Mobility Management) allows remote attackers to access sensitive information without authentication or user interaction due to missing data encryption. It affects devices using MediaTek chipsets with vulnerable modem firmware. Attackers can potentially intercept unencrypted communications between the device and cellular network.
💻 Affected Systems
- MediaTek modem chipsets with EMM functionality
📦 What is this software?
L9 by Mediatek
Lr11 by Mediatek
Lr12 by Mediatek
Lr12a by Mediatek
Lr13 by Mediatek
Nr15 by Mediatek
⚠️ Risk & Real-World Impact
Worst Case
Remote attackers could intercept sensitive modem communications including IMSI, location data, network authentication information, and potentially other device identifiers transmitted over cellular networks.
Likely Case
Information disclosure of device identifiers and network metadata that could be used for tracking, profiling, or as part of broader attack chains.
If Mitigated
Limited impact with proper network segmentation and monitoring, though sensitive data exposure remains possible.
🎯 Exploit Status
Requires ability to intercept cellular communications; no public exploit code available
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware with patch ID MOLY00716585
Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/January-2022
Restart Required: Yes
Instructions:
1. Contact device manufacturer for firmware updates 2. Apply MediaTek-provided modem firmware patch 3. Reboot device after update
🔧 Temporary Workarounds
Disable cellular data when not needed
androidReduce attack surface by disabling cellular data connectivity when Wi-Fi is available
Settings > Network & Internet > Mobile network > Mobile data (toggle off)
🧯 If You Can't Patch
- Monitor for suspicious cellular network activity and unauthorized base station connections
- Use VPN for all cellular data communications to add encryption layer
🔍 How to Verify
Check if Vulnerable:
Check device modem firmware version and compare against MediaTek security bulletinCheck Version:
adb shell getprop | grep gsm.version.baseband (for Android devices)Verify Fix Applied:
Verify modem firmware has been updated to version containing patch MOLY00716585📡 Detection & Monitoring
Log Indicators:
- Unusual modem firmware version changes
- Suspicious base station connections
Network Indicators:
- Unencrypted EMM protocol traffic on cellular interfaces
- Suspicious IMSI catchers in area
SIEM Query:
Device modem firmware version changes OR cellular network authentication anomalies