CVE-2019-15803

Severity Score

9.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Se descubrió un problema en los dispositivos Zyxel GS1900 con firmware anterior a la versión 2.50 (AAHH.0) C0. A través de una secuencia indocumentada de pulsaciones de teclas, se activa la funcionalidad no documentada. Se activa un shell de diagnóstico a través de CTRL-ALT-t, que solicita la contraseña devuelta por fds_sys_passDebugPasswd_ret (). El firmware contiene comprobaciones de control de acceso que determinan si los usuarios remotos pueden acceder a esta funcionalidad. La función que realiza esta comprobación (fds_sys_remoteDebugEnable_ret en libfds.so) siempre devuelve VERDADERO sin realizar comprobaciones reales. El menú de diagnóstico permite leer / escribir registros arbitrarios y varios otros parámetros de configuración que se cree que están relacionados con los chips de la interfaz de red.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2019-08-29 CVE Reserved
2019-11-14 CVE Published
2023-12-24 EPSS Updated
2024-08-05 CVE Updated
2024-08-05 First Exploit
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-287: Improper Authentication

CAPEC

References (2)

URL	Tag	Source

URL	Date	SRC
https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html	2024-08-05

URL	Date	SRC

URL	Date	SRC
https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml	2020-08-24

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Zyxel Search vendor "Zyxel"	Gs1900-8 Firmware Search vendor "Zyxel" for product "Gs1900-8 Firmware"	< 2.50\(aahh.0\)c0 Search vendor "Zyxel" for product "Gs1900-8 Firmware" and version " < 2.50\(aahh.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-8 Search vendor "Zyxel" for product "Gs1900-8"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-8hp Firmware Search vendor "Zyxel" for product "Gs1900-8hp Firmware"	< 2.50\(aahi.0\)c0 Search vendor "Zyxel" for product "Gs1900-8hp Firmware" and version " < 2.50\(aahi.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-8hp Search vendor "Zyxel" for product "Gs1900-8hp"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-10hp Firmware Search vendor "Zyxel" for product "Gs1900-10hp Firmware"	< 2.50\(aazi.0\)c0 Search vendor "Zyxel" for product "Gs1900-10hp Firmware" and version " < 2.50\(aazi.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-10hp Search vendor "Zyxel" for product "Gs1900-10hp"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-16 Firmware Search vendor "Zyxel" for product "Gs1900-16 Firmware"	< 2.50\(aahj.0\)c0 Search vendor "Zyxel" for product "Gs1900-16 Firmware" and version " < 2.50\(aahj.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-16 Search vendor "Zyxel" for product "Gs1900-16"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-24e Firmware Search vendor "Zyxel" for product "Gs1900-24e Firmware"	< 2.50\(aahk.0\)c0 Search vendor "Zyxel" for product "Gs1900-24e Firmware" and version " < 2.50\(aahk.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-24e Search vendor "Zyxel" for product "Gs1900-24e"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-24 Firmware Search vendor "Zyxel" for product "Gs1900-24 Firmware"	< 2.50\(aahl.0\)c0 Search vendor "Zyxel" for product "Gs1900-24 Firmware" and version " < 2.50\(aahl.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-24 Search vendor "Zyxel" for product "Gs1900-24"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-24hp Firmware Search vendor "Zyxel" for product "Gs1900-24hp Firmware"	< 2.50\(aahm.0\)c0 Search vendor "Zyxel" for product "Gs1900-24hp Firmware" and version " < 2.50\(aahm.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-24hp Search vendor "Zyxel" for product "Gs1900-24hp"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-48 Firmware Search vendor "Zyxel" for product "Gs1900-48 Firmware"	< 2.50\(aahn.0\)c0 Search vendor "Zyxel" for product "Gs1900-48 Firmware" and version " < 2.50\(aahn.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-48 Search vendor "Zyxel" for product "Gs1900-48"	-	-	Safe
Zyxel Search vendor "Zyxel"	Gs1900-48hp Firmware Search vendor "Zyxel" for product "Gs1900-48hp Firmware"	< 2.50\(aaho.0\)c0 Search vendor "Zyxel" for product "Gs1900-48hp Firmware" and version " < 2.50\(aaho.0\)c0"	-	Affected	in	Zyxel Search vendor "Zyxel"	Gs1900-48hp Search vendor "Zyxel" for product "Gs1900-48hp"	-	-	Safe