CVE-2017-20204
Published: 15 October 2025
Summary
CVE-2017-20204 is a critical-severity Inclusion of Undocumented Features or Chicken Bits (CWE-1242) vulnerability in Dbltek (inferred from references). Its CVSS base score is 9.3 (Critical).
Operationally, ranked in the top 20.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2017-18921
Vulnerability details
DBLTek GoIP devices (models GoIP 1, 4, 8, 16, and 32) contain an undocumented vendor backdoor in the Telnet administrative interface that allows remote authentication as an undocumented user via a proprietary challenge–response scheme which is fundamentally flawed. Because the…
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challenge response can be computed from the challenge itself, a remote attacker can authenticate without knowledge of a secret and obtain a root shell on the device. This can lead to persistent remote code execution, full device compromise, and arbitrary control of the device and any managed services. The firmware used within these devices was updated in December 2016 to make this vulnerability more complex to exploit. However, it is unknown if DBLTek has taken steps to fully mitigate.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requiring an inventory that accurately reflects the system forces documentation of all components, making inclusion of undocumented features or chicken bits harder to achieve without detection.
Review and update processes include scrutiny of undocumented features or debug mechanisms provided by component manufacturers.
Requires transparency and verification of delivered components, limiting undocumented features or debug hooks introduced upstream.
Discourages undocumented features or chicken bits by demanding transparency and verification that only intended, documented behavior is present.
Developing critical components internally avoids undocumented features and chicken bits present in vendor hardware or software.
Requiring screened developers with proper access limits the introduction of undocumented features or debug 'chicken bits' that could be exploited later.
Inspection can uncover undocumented features or chicken bits that result from tampering or malicious insertion.