CVE intelligence and bounded remediation
CVE-2017-18371 — Billion 5200W-T Firmware security vulnerability
The ZyXEL P660HN-T1A v2 TCLinux Fw #7.3.37.6 router distributed by TrueOnline has three user accounts with default passwords, including two hardcoded service accounts: one with the username true and password true, and another with the username supervisor and password zyad1234. These accounts can be used to login to the web interface, exploit authenticated command injections, and change router settings for malicious purposes.
- Severity
- Critical
- CVSS
- 9.8 (3.0)
- Published
- 2019-05-02
- CISA KEV
- Not currently listed
- Ecosystem
- operating-system
- Weaknesses
- CWE-798
Affected products
- billion / 5200w-t_firmware / 7.3.8.0
- zyxel / p660hn-t1a_v2_firmware / 7.3.37.6
- zyxel / p660hn-t1a_v1_firmware / 7.3.37.6
Matched remediation archetype
Authentication bypass and missing authentication
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
- Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
- Review session, token, credential, and proxy trust configuration without attempting account takeover.
Remediate safely
- Apply the supported fix and centralize fail-closed authentication before protected request handling.
- Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
- Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.
Authoritative sources
Complete CVE record and remediation plan
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