Advantech WebAccess

1. EXECUTIVE SUMMARY

• CVSS v3 8.4
• ATTENTION: Exploitable remotely/low skill level to exploit
• Vendor: Advantech
• Equipment: WebAccess
• Vulnerabilities: Improper Access Control, Stack-based Buffer Overflow

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow for arbitrary remote code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of WebAccess are affected:

• WebAccess Versions 8.3.2 and prior.

3.2 VULNERABILITY OVERVIEW

3.2.1    IMPROPER ACCESS CONTROL CWE-284

During installation, the application installer disables user access control and does not re-enable it after the installation is complete. This could allow an attacker to run elevated arbitrary code.

CVE-2018-17908 has been assigned to this vulnerability. A CVSS v3 base score of 8.4 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.2.2    STACK-BASED BUFFER OVERFLOW CWE-121

The application fails to properly validate the length of user-supplied data, causing a buffer overflow condition that allows for arbitrary remote code execution.

CVE-2018-17910 has been assigned to this vulnerability. A CVSS v3 base score of 7.8 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Energy, Water and Wastewater Systems
• COUNTRIES/AREAS DEPLOYED: East Asia, United States, and Europe
• COMPANY HEADQUARTERS LOCATION: Taiwan

3.4 RESEARCHER

Mat Powell of Trend Micro’s Zero Day Initiative reported these vulnerabilities to NCCIC.

4. MITIGATIONS

Advantech has released Version 8.3.3 of WebAccess to address the reported vulnerabilities. Users can download the latest version of WebAccess at the following location:

http://support.advantech.com/support/DownloadSRDetail_New.aspx?SR_ID=1-MS9MJV&Doc_Source=Download

NCCIC 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.

NCCIC reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

NCCIC also provides a section for control systems security recommended practices on the ICS-CERT web page. 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-CERT website 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 NCCIC for tracking and correlation against other incidents.

No known public exploits specifically target these vulnerabilities.