1. EXECUTIVE SUMMARY

  • CVSS v3 7.5
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Siemens
  • Equipment: SINEMA Remote Connect Server
  • Vulnerabilities: Missing Release of Resource after Effective Lifetime, Infinite Loop

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to cause a memory leak or an infinite loop situation resulting in a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following Siemens products are affected:

  • SINEMA Remote Connect Server: All versions prior to v3.0

3.2 VULNERABILITY OVERVIEW

3.2.1    MISSING RELEASE OF RESOURCE AFTER EFFECTIVE LIFETIME CWE-772

The affected product is vulnerable to a memory leak, which may allow an attacker to cause a denial-of-service condition.

CVE-2019-19956 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).

3.2.2    LOOP WITH UNREACHABLE EXIT CONDITION (‘INFINITE LOOP’) CWE-835

The affected product is vulnerable to an infinite loop, which may allow an attacker to cause a denial-of-service condition.

CVE-2020-7595 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).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

Siemens recommends applying updates where applicable:

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-292794

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

  • Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
  • Locate control system networks and remote devices behind firewalls, and isolate them from the business network.
  • When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices.

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.cisa.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.cisa.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.

Source:

https://us-cert.cisa.gov/ics/advisories/icsa-21-103-08