Siemens TIM 4R-IE Devices Improper Authentication (CVE-2016-4953)

high Tenable OT Security Plugin ID 501103


The remote OT asset is affected by a vulnerability.


ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time.

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The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at

Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:

- Deactivate NTP-based time synchronization of the device, if enabled. The feature is disabled by default.
- Configure an additional firewall to prevent communication to the Port UDP/123 of an affected device.
- Migrate to a successor product.

As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens operational guidelines for Industrial Security and following the recommendations in the product manuals.

For additional information, please refer to Siemens Security Advisory SSA-497656

See Also

Plugin Details

Severity: High

ID: 501103

Version: 1.2

Type: remote

Family: Tenable.ot

Published: 5/2/2023

Updated: 7/24/2023

Supported Sensors: Tenable OT Security

Risk Information


Risk Factor: Low

Score: 3.6


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2016-4953


Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:siemens:simatic_net_cp_443-1_opc_ua_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 7/5/2016

Vulnerability Publication Date: 7/5/2016

Reference Information

CVE: CVE-2016-4953

CWE: 287


GLSA: GLSA-201607-15

SuSE: SUSE-SU-2016:1563, SUSE-SU-2016:1584, SUSE-SU-2016:1602, openSUSE-SU-2016:1583, openSUSE-SU-2016:1636