1. EXECUTIVE SUMMARY
- CVSS v3 7.5
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: Siemens
- Equipment: Various SCALANCE, SIMATIC, SIPLUS products
- Vulnerabilities: Data Processing Errors, NULL Pointer Dereference
2. UPDATE INFORMATION
This updated advisory is a follow-up to the advisory update titled ICSA-20-042-02 Siemens Industrial Products SNMP Vulnerabilities (Update C) that was published February 9, 2021, to the ICS webpage on us-cert.cisa.gov.
3. RISK EVALUATION
Successful exploitation of these vulnerabilities could allow remote attackers to conduct a denial-of-service attack by sending specially crafted packets to Port 161/UDP (SNMP).
4. TECHNICAL DETAILS
4.1 AFFECTED PRODUCTS
The following Siemens products are affected:
- IE/PB LINK PN IO (including SIPLUS NET variants): All versions prior to v4.0.1
——— Begin Update D Part 1 of 2 ———
- SCALANCE S602: All versions prior to v4.1
- SCALANCE S612: All versions prior to v4.1
- SCALANCE S623: All versions prior to v4.1
- SCALANCE S627-2M: All versions prior to v4.1
——— End Update D Part 1 of 2 ———
- SIMATIC CP 1623: All versions prior to Version 14.00.15.00_51.25.00.01
- SIMATIC CP 1626: All versions prior to v1.1.1
- SIMATIC CP 1628: All versions prior to Version 14.00.15.00_51.25.00.01
- SIMATIC CP 343-1 Advanced (including SIPLUS NET variants): All versions
- SIMATIC CP 443-1 (including SIPLUS NET variants): All versions
- SIMATIC CP 443-1 Advanced (including SIPLUS NET variants): All versions
- SIMATIC CP 443-1 OPC UA: All versions
- TIM 1531 IRC (including SIPLUS NET variants): All versions
4.2 VULNERABILITY OVERVIEW
4.2.1 DATA PROCESSING ERRORS CWE-19
An error in the message handling of SNMP messages allows remote attackers to cause a denial-of-service condition and execute arbitrary code via a crafted packet sent on Port 161/UDP (SNMP).
CVE-2015-5621 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
4.2.2 NULL POINTER DEREFERENCE CWE-476
A NULL pointer exception bug within the SNMP handling code allows authenticated attacker to remotely cause a denial-of-service condition via a crafted packet sent on Port 161/UDP (SNMP).
CVE-2018-18065 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
4.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Chemical, Energy, Food and Agriculture, Healthcare and Public Health, Transportation Systems, and Water and Wastewater Systems
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Germany
4.4 RESEARCHER
Artem Zinenko of Kaspersky Lab reported these vulnerabilities to Siemens.
5. MITIGATIONS
Siemens has released updates for several affected products and recommends users update to the new version. Siemens is preparing further updates and recommends specific countermeasures until patches are available.
- For IE/PB LINK PN IO, update to v4.0.1
——— Begin Update D Part 2 of 2 ———
- For SCALANCE S602, SCALANCE S612, SCALANCE S623, and SCALANCE S627-2M products: Update to v4.1 (Update is only available via Siemens Support contact). Upgrade hardware to successor product from SCALANCE SC-600 family
——— End Update D Part 2 of 2 ———
- For SIMATIC NET CP 1623 and SIMATIC NET CP 1628, update to SIMATIC NET PC Software Version 16
- For SIMATIC NET CP 1626, update to v1.1.1 or later version
- For TIM 1531 IRC or SIPLUS NET variants, update to Version 2.0
Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
- Disable SNMP if this is supported by the product (refer to the product documentation). Disabling SNMP fully mitigates these vulnerabilities.
- Protect network access to Port 161/UDP of affected devices.
- Apply cell protection concept and implement defense-in-depth.
- Use VPN for protecting network communication between cells.
As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemens’ operational guidelines for Industrial Security, and follow the recommendations in the product manuals.
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.gov. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage on us-cert.gov in the Technical Information Paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.
No known public exploits specifically target these vulnerabilities.
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