WECON LeviStudio Buffer Overflow Vulnerabilities

OVERVIEW

Independent security researchers Rocco Calvi and Brian Gorenc, working with Trend Micro’s Zero Day Initiative, have identified buffer overflow vulnerabilities in WECON’s LeviStudio software. WECON has not released a product fix to addresses the buffer overflow vulnerabilities in the LeviStudio software.

AFFECTED PRODUCTS

The following LeviStudio versions are affected:

• LeviStudio, all versions.

IMPACT

Successful exploitation of these vulnerabilities may allow remote code execution.

Impact to individual organizations depends on many factors that are unique to each organization. NCCIC/ICS-CERT recommends that organizations evaluate the impact of these vulnerabilities based on their operational environment, architecture, and product implementation.

BACKGROUND

WECON is a China-based company.

The affected product, LeviStudio, is an HMI programming software. According to WECON, LeviStudio is deployed across several sectors including Chemical, Critical Manufacturing, and Energy. WECON estimates that this product is primarily used in Asia.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

HEAP-BASED BUFFER OVERFLOWCWE-122: Heap-based Buffer Overflow, http://cwe.mitre.org/data/definitions/122.html, web site last accessed July 07, 2016.

Specific flaws in the handling of some files may allow an attacker to cause a heap-based buffer overflow and execute code in the context of the running process.

CVE-2016-4533NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-4533, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v3 base score of 5.3 has been assigned; the CVSS vector string is (AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L, web site last accessed July 07, 2016.

STACK-BASED BUFFER OVERFLOWCWE-121: Stack-based Buffer Overflow, http://cwe.mitre.org/data/definitions/121.html, web site last accessed July 07, 2016.

Specific flaws in the handling of some files may allow an attacker to cause a stack-based buffer overflow and execute code in the context of the running process.

CVE-2016-5781NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5781, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v3 base score of 5.3 has been assigned; the CVSS vector string is (AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L, web site last accessed July 07, 2016.

VULNERABILITY DETAILS

EXPLOITABILITY

These vulnerabilities are not exploitable remotely and cannot be exploited without user interaction. The exploit is only triggered when a local user runs the vulnerable application and loads the malformed file or visits a malicious web site.

EXISTENCE OF EXPLOIT

No known public exploits specifically target these vulnerabilities.

DIFFICULTY

An attacker with low skill would be able to exploit these vulnerabilities. Crafting a working exploit for these vulnerabilities would not be difficult; however, social engineering is required to convince the user to accept the malformed file or visit a malicious web site. This decreases the likelihood of a successful exploit.

MITIGATION

WECON has not released a product fix to address the buffer overflow vulnerabilities in the LeviStudio software. WECON has indicated that they are planning to release a product fix; however, a definitive release date has not been established.

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. Specifically, users should:

• Ensure that untrusted files are not uploaded or run without verifying the integrity of files.
• Interact with and only obtain files, software, and software patches from trustworthy highly reputable sources.
• Limit access to those assets using the LeviStudio software to authorized personnel.
• Ensure that employees with access to the LeviStudio software are fully aware of the ongoing potential for social engineering attacks and are trained to identify and avoid social engineering attacks.
• 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.

ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

ICS-CERT also provides a section for control systems security recommended practices on the ICS-CERT web page at: http://ics-cert.us-cert.gov/content/recommended-practices. 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 in the ICS‑CERT Technical Information Paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies, that is available for download from the ICS-CERT web site (http://ics-cert.us-cert.gov/).

Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to ICS-CERT for tracking and correlation against other incidents.

In addition, ICS-CERT recommends that users take the following measures to protect themselves from social engineering attacks:

1. Do not click web links or open unsolicited attachments in email messages.
2. Refer to Recognizing and Avoiding Email ScamsRecognizing and Avoiding Email Scams, http://www.us-cert.gov/reading_room/emailscams_0905.pdf, web site last accessed July 7, 2016. for more information on avoiding email scams.

Refer to Avoiding Social Engineering and Phishing AttacksNational Cyber Alert System Cyber Security Tip ST04-014, http://www.us-cert.gov/cas/tips/ST04-014.html, web site last accessed July 7, 2016. for more information on social engineering attacks.