-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2016.1695
             WECON LeviStudio Buffer Overflow Vulnerabilities
                               11 July 2016

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           WECON LeviStudio
Publisher:         ICS-CERT
Operating System:  Windows
Impact/Access:     Execute Arbitrary Code/Commands -- Remote with User Interaction
Resolution:        Mitigation
CVE Names:         CVE-2016-5781 CVE-2016-4533 

Original Bulletin: 
   http://ics-cert.us-cert.gov/advisories/ICSA-16-189-01

- --------------------------BEGIN INCLUDED TEXT--------------------

Advisory (ICSA-16-189-01)

WECON LeviStudio Buffer Overflow Vulnerabilities

Original release date: July 07, 2016

Legal Notice

All information products included in http://ics-cert.us-cert.gov are provided
"as is" for informational purposes only. The Department of Homeland Security 
(DHS) does not provide any warranties of any kind regarding any information 
contained within. DHS does not endorse any commercial product or service, 
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For 
more information about TLP, see http://www.us-cert.gov/tlp/.

OVERVIEW

Independent security researchers Rocco Calvi and Brian Gorenc, working with 
Trend Micros Zero Day Initiative, have identified buffer overflow 
vulnerabilities in WECONs 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 OVERFLOW [a]

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-2016-4533 [b] 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). [c]

STACK-BASED BUFFER OVERFLOWd

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-2016-5781 [e] 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). [f]

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 ICSCERT 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:

Do not click web links or open unsolicited attachments in email messages.

Refer to Recognizing and Avoiding Email Scams [g] for more information on 
avoiding email scams.

Refer to Avoiding Social Engineering and Phishing Attacks [h] for more 
information on social engineering attacks.

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

b. NVD, 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.

c. CVSS Calculator, 
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S..., 
web site last accessed July 07, 2016.

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

e. NVD, 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.

f. CVSS Calculator, 
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S..., 
web site last accessed July 07, 2016.

g. Recognizing and Avoiding Email Scams, 
http://www.us-cert.gov/reading_room/emailscams_0905.pdf, web site last 
accessed July 7, 2016.

h. National 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.

Contact Information

For any questions related to this report, please contact ICS-CERT at:

Email: ics-cert@hq.dhs.gov (link sends e-mail)

Toll Free: 1-877-776-7585

International Callers: (208) 526-0900

For industrial control systems security information and incident reporting: 
http://ics-cert.us-cert.gov

ICS-CERT continuously strives to improve its products and services. You can 
help by choosing one of the links below to provide feedback about this 
product.

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
===========================================================================
-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967
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=StVs
-----END PGP SIGNATURE-----