SUMMARY
Security researchers discovered and disclosed 33 vulnerabilities in several open-source TCP/IP stacks for embedded devices, also known as “AMNESIA:33” vulnerabilities.
This advisory describes the impact of two of these vulnerabilities (CVE-2020-13987, CVE-2020-17437) to Siemens products.
Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not available.
The impact of another “AMNESIA:33” vulnerability (CVE-2020-13988) is described in Siemens Security Advisory SSA-541017 .
GENERAL SECURITY RECOMMENDATIONS
As a general security measure, Siemens strongly recommends to protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends to configure the environment according to Siemens’ operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security ), and to follow the recommendations in the product manuals.
Additional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity
PRODUCT DESCRIPTION
SENTRON PAC Meter products are power measuring devices for precise energy management and transparent information acquisition.
The SENTRON 3VA COM100/COM800 breaker data server is used as a gateway and enables communication between 3VA MCCB (Molded Case Circuit Breaker) devices and automation systems.
The SENTRON 3VA DSP800 display device is used to display values retrieved from 3VA MCCB (Molded Case Circuit Breaker) devices.
VULNERABILITY CLASSIFICATION
The vulnerability classification has been performed by using the CVSS scoring system in version 3.1
(CVSS v3.1) (https://www.first.org/cvss ). The CVSS environmental score is specific to the customer’s
environment and will impact the overall CVSS score. The environmental score should therefore be
individually defined by the customer to accomplish final scoring.
An additional classification has been performed using the CWE classification, a community-developed
list of common software security weaknesses. This serves as a common language and as a baseline for
weakness identification, mitigation, and prevention efforts. A detailed list of CWE classes can be found
at: https://cwe.mitre.org/ .
Vulnerability CVE-2020-13987
The TCP/IP stack (uIP) in affected devices is vulnerable to out-of-bounds read when calculating the checksum for IP packets. (FSCT-2020-0009)
An attacker located in the same network could trigger a Denial-of-Service condition on the device by sending a specially crafted IP packet.
CVSS v3.1 Base Score
6.5
CVSS Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C
CWE:
CWE-125: Out-of-bounds Read
Vulnerability CVE-2020-17437
The TCP/IP stack (uIP) in affected devices is vulnerable to out-of-bounds write when processing TCP packets with urgent pointer (URG) where the location of the TCP data payload is calculated improperly. (FSCT-2020-0018)
An attacker located in the same network could trigger a Denial-of-Service condition on the device by sending a specially crafted IP packet.
CVSS v3.1 Base Score
6.5
CVSS Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C
CWE:
CWE-787: Out-of-bounds Write