CVE-2021-21933: 
Advantech R-SeeNet vulnerability analysis and mitigation

A SQL injection vulnerability exists in the Advantech R-SeeNet 2.4.15 application, identified as CVE-2021-21933. The vulnerability was discovered in the 'device_list' page, specifically in the 'esn_filter' parameter. This security flaw allows authenticated users to perform SQL injection attacks through specially-crafted HTTP requests, which can be executed either by any authenticated user or through cross-site request forgery (Talos Intelligence).

The vulnerability stems from misuse of prepared statements in conjunction with stored procedures and SQL concatenation. Despite initial sanitization of variables used in SQL queries, the protection is lost when invoked against the database. The vulnerability has a CVSS v3.1 base score of 6.5 (MEDIUM) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N according to NVD, while Talos assigned a higher CVSS v3.0 score of 7.7 (HIGH) with vector string CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N (NVD, Talos Intelligence).

Successful exploitation of this vulnerability could allow attackers to retrieve sensitive information from the product's database. The vulnerability affects the confidentiality of the system while maintaining normal integrity and availability (CISA).

Advantech recommends updating to Version 2.4.17 or later to address this vulnerability. Additionally, CISA recommends minimizing network exposure for all control system devices, ensuring they are not accessible from the Internet, locating control system networks behind firewalls, isolating them from business networks, and using secure methods like VPNs when remote access is required (CISA).