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[email protected]CVE-2019-15803

HistoryNov 14, 2019 - 9:15 p.m.

CVE-2019-15803

2019-11-1421:15:11

CWE-287

[email protected]

web.nvd.nist.gov

zyxel gs1900

firmware

vulnerability

remote access

undocumented functionality

diagnostics shell

access control

9.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

9.2 High

AI Score

Confidence

High

6.4 Medium

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:L/Au:N/C:P/I:P/A:N

0.011 Low

EPSS

Percentile

84.8%

JSON

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an undocumented sequence of keypresses, undocumented functionality is triggered. A diagnostics shell is triggered via CTRL-ALT-t, which prompts for the password returned by fds_sys_passDebugPasswd_ret(). The firmware contains access control checks that determine if remote users are allowed to access this functionality. The function that performs this check (fds_sys_remoteDebugEnable_ret in libfds.so) always return TRUE with no actual checks performed. The diagnostics menu allows for reading/writing arbitrary registers and various other configuration parameters which are believed to be related to the network interface chips.

Affected configurations

NVD

Node

zyxelgs1900-8_firmwareRange<2.50\(aahh.0\)c0

AND

zyxelgs1900-8Match-

Node

zyxelgs1900-8hp_firmwareRange<2.50\(aahi.0\)c0

AND

zyxelgs1900-8hpMatch-

Node

zyxelgs1900-10hp_firmwareRange<2.50\(aazi.0\)c0

AND

zyxelgs1900-10hpMatch-

Node

zyxelgs1900-16_firmwareRange<2.50\(aahj.0\)c0

AND

zyxelgs1900-16Match-

Node

zyxelgs1900-24e_firmwareRange<2.50\(aahk.0\)c0

AND

zyxelgs1900-24eMatch-

Node

zyxelgs1900-24_firmwareRange<2.50\(aahl.0\)c0

AND

zyxelgs1900-24Match-

Node

zyxelgs1900-24hp_firmwareRange<2.50\(aahm.0\)c0

AND

zyxelgs1900-24hpMatch-

Node

zyxelgs1900-48_firmwareRange<2.50\(aahn.0\)c0

AND

zyxelgs1900-48Match-

Node

zyxelgs1900-48hp_firmwareRange<2.50\(aaho.0\)c0

AND

zyxelgs1900-48hpMatch-

CPENameOperatorVersion
zyxel:gs1900-8_firmwarezyxel gs1900-8 firmwarelt2.50\(aahh.0\)c0

CPE	Name	Operator	Version
zyxel:gs1900-8_firmware	zyxel gs1900-8 firmware	lt	2.50\(aahh.0\)c0

References

jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html

www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml

9.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

9.2 High

AI Score

Confidence

High

6.4 Medium

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:L/Au:N/C:P/I:P/A:N

0.011 Low

EPSS

Percentile

84.8%

JSON

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