Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2019-15803

Severity CVSS v4.0:
Pending analysis
Type:
CWE-287 Authentication Issues
Publication date:
14/11/2019
Last modified:
24/08/2020

Description

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N CVSS v3.1 Severity and Metrics:

Base Score: 9.10 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): None

Base Score 3.x
9.10
Severity 3.x
CRITICAL
Vector 2.0
AV:N/AC:L/Au:N/C:P/I:P/A:N CVSS v2.0 Severity and Metrics:

Base Score: 6.40 MEDIUM
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Authentication (Au): None
Confidentiality (C): Physical
Integrity (I): Physical
Availability (A): None

Base Score 2.0
6.40
Severity 2.0
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:o:zyxel:gs1900-8_firmware:*:*:*:*:*:*:*:* 2.50\(aahh.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-8:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-8hp_firmware:*:*:*:*:*:*:*:* 2.50\(aahi.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-8hp:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-10hp_firmware:*:*:*:*:*:*:*:* 2.50\(aazi.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-10hp:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-16_firmware:*:*:*:*:*:*:*:* 2.50\(aahj.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-16:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-24e_firmware:*:*:*:*:*:*:*:* 2.50\(aahk.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-24e:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-24_firmware:*:*:*:*:*:*:*:* 2.50\(aahl.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-24:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-24hp_firmware:*:*:*:*:*:*:*:* 2.50\(aahm.0\)c0 (excluding)
cpe:2.3:h:zyxel:gs1900-24hp:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gs1900-48_firmware:*:*:*:*:*:*:*:* 2.50\(aahn.0\)c0 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools