Siemens SCALANCE XM-400/XR-500 CVE-2020-28393 Remote DoS via OSPF

Vulnerability Key Information 1. Executive Summary CVSS v3: 7.5 Note: Remotely exploitable / Low attack complexity Vendor: Siemens Devices: SCALANCE XM-400, XR-500 Vulnerability: Calculation Error 2. Risk Assessment Successful exploitation of this vulnerability may allow an unauthenticated remote attacker to create a permanent denial-of-service condition. 3. Technical Details 3.1 Affected Products Affected Siemens products include: SCALANCE XM-400 Family: All versions prior to v6.4 SCALANCE XR-500 Family: All versions prior to v6.4 3.2 Vulnerability Overview 3.2.1 Calculation Error CWE-682 An unauthenticated remote attacker can create a permanent denial-of-service condition by sending specially crafted OSPF packets. Successful exploitation requires OSPF to be enabled on the affected device. CVE-2020-28393 has been assigned to this vulnerability. The CVSS v3 base score is 7.5; 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 Sector: Multiple sectors Deployed Countries/Regions: Global Company Headquarters Location: Germany 3.4 Researchers Siemens reported this vulnerability to CISA. 4. Mitigations Siemens recommends applying updates when available: SCALANCE XM-400 Family: Upgrade to v6.4 or later SCALANCE XR-500 Family: Upgrade to v6.4 or later Specific workarounds and mitigations that can be applied include: Disable OSPF in the Layer 3 configuration menu (disabled by default). If OSPF is in use, set a password for the OSPF interface and enable MD5 authentication. General security measures also include: Minimize network exposure of all control systems and ensure they are not accessible from the internet. Place control system networks and remote devices behind firewalls, isolated from business networks. When remote access is required, use secure methods such as Virtual Private Networks (VPNs). Ensure systems are updated to the latest version. CISA recommends users implement defensive measures to minimize the risk of exploitation, including minimizing network exposure and using VPNs.

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Siemens SCALANCE XM-400/XR-500 CVE-2020-28393 Remote DoS via OSPF