CVE-2021-40142: 
Telecontrol Server Basic vulnerability analysis and mitigation

In OPC Foundation Local Discovery Server (LDS) before version 1.04.402.463, a vulnerability was discovered that allows remote attackers to cause a denial of service (DoS) condition. The vulnerability was assigned CVE-2021-40142 and was disclosed on August 27, 2021. The vulnerability affects OPC Foundation Local Discovery Server and various Siemens industrial products that incorporate this component (NVD, CISA).

The vulnerability is classified as an improper restriction of operations within the bounds of a memory buffer (CWE-119). Remote attackers can trigger a denial of service condition by sending carefully crafted messages that lead to access of a memory location after the end of a buffer. The vulnerability has been assigned a CVSS v3.1 base score of 7.5 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating it can be exploited remotely with low attack complexity and requires no privileges or user interaction (NVD).

Successful exploitation of this vulnerability could allow an attacker to cause a denial of service condition on the affected service or device, potentially disrupting industrial operations. The vulnerability affects availability but does not impact confidentiality or integrity of the system (CISA).

The OPC Foundation has released version 1.04.402.463 of the Local Discovery Server to address this vulnerability. Siemens has also released updates for affected industrial products and recommends users to update to the latest versions. For systems where updates cannot be immediately applied, Siemens recommends deactivating the OPC Local Discovery Server service if supported by the product use case, using VPN for protecting network communication between cells, and operating devices in a protected IT environment according to Siemens' operational guidelines for industrial security (CISA).