China-Made ZBT Routers Ship With Two Implants Giving Unauthenticated Attackers Root Access
VulnCheck discloses two factory implants, SPEAKINGSTONE and DARKLANTERN, in ZBT router firmware granting unauthenticated remote attackers root command execution.
VulnCheck found two previously undocumented implants in firmware from Shenzhen Zhibotong Electronics (ZBT), tracked as CVE-2026-74232 (SPEAKINGSTONE) and CVE-2026-74233 (DARKLANTERN), each rated 9.8 on CVSS 3.1. SPEAKINGSTONE (yunmgrd) beacons to a hardcoded C2 over UDP port 10000 and supports root command execution, PPPoE credential exfiltration, DNS hijacking, and reverse SSH tunnels; DARKLANTERN (infosrvd) listens on UDP port 9992 with weak hardcoded authentication. Scanning found 203 internet-facing DARKLANTERN instances across 22 countries, and 392 devices reported to the SPEAKINGSTONE backup C2, nearly all in China on China Mobile. No fixed firmware release is named, and ZBT's white-labeling means model number rather than brand is the reliable detection check.
A Deep Dive Into Attempted Exploitation of CVE-2023
Mirai-like botnet scans exploit TP-Link EOL router flaw CVE-2023-33538 after CISA KEV addition, though observed exploit code is flawed.
Unit 42 observed large-scale automated scans attempting to exploit CVE-2023-33538 in end-of-life TP-Link TL-WR940N, TL-WR740N and TL-WR841N routers after CISA added the flaw to its KEV catalog in June 2025. HTTP GET requests inject commands via the ssid1 parameter at the /userRpm/WlanNetworkRpm endpoint to download and execute an arm7 ELF binary, a Mirai variant related to the Condi IoT botnet. Firmware emulation and reverse engineering showed the observed exploits are flawed and would fail, but the underlying vulnerability is real and successful exploitation requires authentication to the router's web interface. TP-Link confirmed the devices are end-of-life with no patches available and recommends replacing units and eliminating default credentials.