How CVE-2025-20666 Works
This vulnerability occurs in certain modem firmware when processing maliciously crafted signals from a rogue base station. An unhandled exception in the modem stack causes a system crash, leading to a persistent denial of service (DoS). Attackers can exploit this by impersonating a legitimate cell tower, forcing vulnerable devices to connect and triggering the crash without user interaction. The flaw resides in improper error handling during radio resource control (RRC) signaling, allowing malformed packets to disrupt the modem’s operation.
DailyCVE Form:
Platform: Modem Firmware
Version: Pre-MOLY00650610
Vulnerability: Uncaught Exception
Severity: Critical
Date: 05/06/2025
What Undercode Say:
Exploitation Analysis:
1. Rogue Base Station Setup:
- Use SDR (Software-Defined Radio) tools like `gr-lte` or `srsRAN` to emulate a malicious cell tower.
sudo srsenb --rf.device_args="driver=uhd" --rf.freq=1900M
2. Craft Malicious RRC Packets:
- Modify RRC connection setup messages to include invalid parameters.
import socket malformed_packet = b'\x00\x01\xFF\xFF\x00\x00\x00' Invalid IE values
3. Force Connection:
- Broadcast a high-priority PLMN to lure target devices.
Protection Measures:
1. Patch Firmware:
flash_tool --patch=MOLY00650610 --device=/dev/ttyMODEM
2. Network Monitoring:
- Detect rogue base stations using:
tshark -i any -Y "gsm_a.dtap.msg == rrc_connection_setup"
3. Modem Hardening:
- Disable automatic connections to non-whitelisted towers via AT commands:
AT+COPS=1,2,"MCCMNC"
4. CVSS 4.0 Mitigation:
- Attack Vector: Network (AV:N)
- Impact: High (Confidentiality: N, Integrity: N, Availability: H)
5. Debugging Crash Logs:
dmesg | grep -i "modem_crash"
6. Vendor Workaround:
- MediaTek recommends disabling “auto-connect” in affected firmware versions.
7. Exploit PoC Detection:
if rrc_packet.contains(invalid_ies): drop_packet()
8. SDR Countermeasures:
- Use RF jamming detection tools like
kalibrate-rtl.
9. Firmware Rollback Prevention:
efuse_tool --lock=modem_fw
10. CVE Tracking:
- Monitor NVD updates for new patches.
No further commentary.
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
