CVE-2020-10616: 
Opto 22 SoftPAC vulnerability analysis and mitigation

CVE-2020-10616 is a security vulnerability affecting Opto 22 SoftPAC Project Version 9.6 and prior versions. The vulnerability was discovered and reported by Mashav Sapir of Claroty to CISA, and was publicly disclosed on May 14, 2020. The issue stems from an uncontrolled search path element vulnerability where SoftPAC does not specify the path of multiple imported .dll files (CISA Advisory).

The vulnerability is classified as an Uncontrolled Search Path Element (CWE-427) with a CVSS v3.1 base score of 8.8 HIGH (Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). The technical issue arises from SoftPAC's failure to specify paths for multiple imported .dll files, which creates a security weakness that can be exploited when the service starts (NVD, CISA Advisory).

Successful exploitation of this vulnerability could allow an attacker to replace legitimate .dll files and execute malicious code whenever the service starts. This vulnerability affects critical infrastructure sectors including Commercial Facilities, Critical Manufacturing, Information Technology, and Transportation Systems worldwide (CISA Advisory).

The vulnerability is exploitable remotely and requires a low skill level to exploit. An attacker can replace the unspecified .dll files and execute code whenever the service starts. As of the advisory publication, there were no known public exploits specifically targeting this vulnerability (CISA Advisory).

Opto 22 has released PAC Project 10.3 to address this vulnerability. CISA recommends users implement defensive measures including: monitoring or restricting Port 22000 at the firewall, minimizing network exposure for control system devices, ensuring systems are not accessible from the Internet, and using secure methods like VPNs when remote access is required. Users should also locate control system networks and remote devices behind firewalls and isolate them from the business network (CISA Advisory).