1. EXECUTIVE SUMMARY
- CVSS v3 8.8
- ATTENTION: Exploitable remotely/low skill level to exploit
- Vendor: PerFact
- Equipment: OpenVPN-Client
- Vulnerability: External Control of System or Configuration Setting
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow for local privilege escalation or remote code execution through a malicious webpage.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of OpenVPN-Client are affected:
- OpenVPN-Client, Versions 1.4.1.0 and prior
3.2 VULNERABILITY OVERVIEW
3.2.1 EXTERNAL CONTROL OF SYSTEM OR CONFIGURATION SETTING CWE-15
An attacker can take leverage on this architecture and send the config command from any application running on the local host machine to force the back-end server into initializing a new open-VPN instance with arbitrary open-VPN configuration. This could result in the attacker achieving execution with privileges of a SYSTEM user.
CVE-2021-27406 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
3.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Sharon Brizinov of Claroty reported this vulnerability to CISA.
4. MITIGATIONS
PerFact has released Version 1.6.0, which mitigates this vulnerability.
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:
- Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
- Locate control system networks and remote devices behind firewalls, and isolate them from the business network.
- When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.cisa.gov. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage on us-cert.cisa.gov in the Technical Information Paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.
No known public exploits specifically target this vulnerability.
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