ESB-2019.1113 - [Win] Advantech WebAccess/SCADA: Multiple vulnerabilities 2019-04-03

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.1113
                         Advantech WebAccess/SCADA
                               3 April 2019

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

Product:           Advantech WebAccess/SCADA
Publisher:         ICS-CERT
Operating System:  Windows
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-6554 CVE-2019-6552 CVE-2019-6550

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-19-092-01

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Advisory (ICSA-19-092-01)

Advantech WebAccess/SCADA

Original release date: April 02, 2019

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1. EXECUTIVE SUMMARY

  o CVSS v3 9.8
  o ATTENTION: Exploitable remotely/low skill level to exploit
  o Vendor: Advantech
  o Equipment: WebAccess/SCADA
  o Vulnerabilities: Command Injection, Stack-based Buffer Overflow, Improper
    Access Control

2. RISK EVALUATION

Successful exploitation of these vulnerabilities may cause a denial of service
and allow remote code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of WebAccess/SCADA, a SCADA software platform, are
affected:

  o WebAccess/SCADA Versions 8.3.5 and prior.

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER NEUTRALIZATION OF SPECIAL ELEMENTS USED IN A COMMAND ('COMMAND
INJECTION') CWE-77

Multiple command injection vulnerabilities, caused by a lack of proper
validation of user-supplied data, may allow remote code execution.

CVE-2019-6552 has been assigned to these vulnerabilities. A CVSS v3 base score
of 9.8 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U
/C:H/I:H/A:H )

3.2.2 STACK-BASED BUFFER OVERFLOW CWE-121

Multiple stack-based buffer overflow vulnerabilities, caused by a lack of
proper validation of the length of user-supplied data, may allow remote code
execution.

CVE-2019-6550 has been assigned to these vulnerabilities. A CVSS v3 base score
of 9.8 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U
/C:H/I:H/A:H ).

3.2.3 IMPROPER ACCESS CONTROL CWE-284

An improper access control vulnerability may allow an attacker to cause a
denial-of-service condition.

CVE-2019-6554 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

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

3.4 RESEARCHER

Mat Powell and Natnael Samson (@NattiSamson) working with Trend Micro's Zero
Day Initiative (ZDI) reported these vulnerabilities to NCCIC.

4. MITIGATIONS

Advantech has released Version 8.4.0 of WebAccess/SCADA to address the reported
vulnerabilities. Users can download the latest version of WebAccess/SCADA at
the following location (registration required):

https://support.advantech.com/support/DownloadSRDetail_New.aspxSR_ID=1-MS9MJV&
Doc_Source=Download

NCCIC recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:

  o Minimize network exposure for all control system devices and/or systems,
    and ensure that they are not accessible from the Internet .
  o Locate control system networks and remote devices behind firewalls, and
    isolate them from the business network.
  o 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.

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