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Siemens has workarounds and mitigations available to handle integer overflow or wraparound, and uncontrolled resource consumption vulnerabilities in its industrial products, according to a report with CISA.

Successful exploitation of these remotely exploitable vulnerabilities, which Siemens self-reported, could cause denial-of-service condition.

In one issue, the kernel is affected by an integer overflow when handling TCP Selective Acknowledgements, which could allow a remote attacker to cause a denial-of-service condition.CVE-2019-11477 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 7.5.

In addition, a remote attacker sending specially crafted TCP Selective Acknowledgment (SACK) sequences may cause a denial-of-service condition.

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CVE-2019-11478 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 5.3.

Also, an attacker may exploit a vulnerability in the TCP retransmission queue implementation kernel when handling TCP Selective Acknowledgements (SACK) to cause a denial-of-service condition.

CVE-2019-11479 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 5.3.

The vulnerabilities affect the following industrial products:
• CM 1542-1: All versions
• CP 1242-7: All versions
• CP 1243-1: All versions
• CP 1243-7 LTE EU: All versions
• CP 1243-7 LTE US: All versions
• CP 1243-8 IRC: All versions
• CP 1542SP-1: All versions
• CP 1542SP-1 IRC: All versions
• CP 1543-1: All versions
• CP 1543SP-1: All versions
• CloudConnect 712: All versions prior to 1.1.5
• ROX II: All versions (Only vulnerable to CVE-2019-11479)
• RUGGEDCOM RM1224: All versions
• S7-1500 CPU 1518(F)-4 PN/DP MFP: All versions
• SCALANCE M800: All versions
• SCALANCE M875: All versions
• SCALANCE S615: All versions
• SCALANCE SC-600: All versions prior to 2.0.1
• SCALANCE W-700 (IEEE 802.11n): All versions
• SCALANCE W1700: All versions
• SCALANCE WLC711: All versions
• SCALANCE WLC712: All versions
• SIMATIC ITC1500: All versions
• SIMATIC ITC1500 PRO: All versions
• SIMATIC ITC1900: All versions
• SIMATIC ITC1900 PRO: All versions
• SIMATIC ITC2200: All versions
• SIMATIC ITC2200 PRO: All versions
• SIMATIC MV500: All versions
• SIMATIC RF166C: All versions
• SIMATIC RF185C: All versions
• SIMATIC RF186C: All versions
• SIMATIC RF186CI: All versions
• SIMATIC RF188C: All versions
• SIMATIC RF188CI: All versions
• SIMATIC RF600R: All versions
• SIMATIC Teleserver Adapter IE Advanced: All versions
• SIMATIC Teleserver Adapter IE Basic: All versions
• SINEMA Remote Connect Server: All versions prior to 2.0 SP1
• SINUMERIK 808D: All versions
• SINUMERIK 828D: All versions
• SINUMERIK 840D sl: All versions
• TIM 1531 IRC: All versions

The products see use in the chemical, critical manufacturing, energy, food and agriculture, and water and wastewater systems sectors. They also see action on a global basis.

An attacker with low skill level could leverage the issues.

Siemens recommends users follow the specific workarounds and mitigations below. Siemens has also released fixes for the following products:
• CloudConnect 712: Update to v1.1.5
• SCALANCE M875: Upgrade hardware to SCALANCE M876-4 or RUGGEDCOM RM1224 and apply patches when available.
• SCALANCE SC-600: Update to v2.0.1
• SINEMA Remote Connect Server: Update to v2.0 SP1

Siemens identified the following specific workarounds and mitigations that customers can apply to reduce the risk:
• Restrict network access to affected devices
• Apply defense-in-depth

As a general security measure, Siemens 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.

Click here for additional information on industrial security by Siemens.

For more information, please see Siemens Security Advisory SSA-462066.

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