1. EXECUTIVE SUMMARY

  • CVSS v3 8.2
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: EIPStackGroup
  • Equipment: OpENer EtherNet/IP
  • Vulnerabilities: Incorrect Conversion Between Numeric Types, Out-of-bounds Read, Reachable Assertion

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could cause a denial-of-service condition and data exposure.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of OpENer EtherNet/IP, are affected:

3.2 VULNERABILITY OVERVIEW

3.2.1    INCORRECT CONVERSION BETWEEN NUMERIC TYPES CWE-681

A specifically crafted packet sent by an attacker to the affected devices may cause a denial-of-service condition. 

CVE-2021-27478 has been assigned to this vulnerability. A CVSS v3 base score of 8.2 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H).

3.2.2    OUT-OF-BOUNDS READ CWE-125

A specifically crafted packet sent by an attacker may allow the attacker to read arbitrary data. 

CVE-2021-27482 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

3.2.3    REACHABLE ASSERTION CWE-617

A specifically crafted packet sent by an attacker may result in a denial-of-service condition.  

CVE-2021-27500 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.4    REACHABLE ASSERTION CWE-617

A specifically crafted packet sent by an attacker may result in a denial-of-service condition.  

CVE-2021-27498 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; 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 SECTORS: Multiple
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Austria

3.4 RESEARCHER

Tal Keren and Sharon Brizinov of Claroty reported these vulnerabilities to CISA.

4. MITIGATIONS

The maintainer of OpENer recommends those affected to apply the latest commits available.

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 that VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize that 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 these vulnerabilities.

Source:

https://us-cert.cisa.gov/ics/advisories/icsa-21-105-02