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             AUSCERT External Security Bulletin Redistribution

                               ESB-2021.3351
          Advisory (icsa-21-280-06) FATEK Automation WinProladder
                              8 October 2021

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

Product:           FATEK Automation WinProladder
Publisher:         ICS-CERT
Operating System:  Windows
Impact/Access:     Execute Arbitrary Code/Commands -- Existing Account
                   Access Confidential Data        -- Existing Account
Resolution:        Mitigation
CVE Names:         CVE-2021-38442 CVE-2021-38440 CVE-2021-38438
                   CVE-2021-38436 CVE-2021-38434 CVE-2021-38430
                   CVE-2021-38426  

Original Bulletin: 
   https://us-cert.cisa.gov/ics/advisories/icsa-21-280-06

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ICS Advisory (ICSA-21-280-06)

FATEK Automation WinProladder

Original release date: October 07, 2021

Legal Notice

All information products included in https://us-cert.cisa.gov/ics 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
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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
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1. EXECUTIVE SUMMARY

  o CVSS v3 7.8
  o ATTENTION: Exploitable remotely/low attack complexity
  o Vendor: FATEK Automation
  o Equipment: WinProladder
  o Vulnerabilities : Out-of-bounds Write, Out-of-bounds Read, Unexpected Sign
    Extension, Stack-based Buffer Overflow, Improper Restriction of Operations
    within the Bounds of a Memory Buffer, Use After Free

2. RISK EVALUATION

Successful exploitation of these vulnerabilities may allow arbitrary code
execution, remote code execution, heap corruption, and unauthorized information
disclosure.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of FATEK Automation WinProladder, a PLC programming
software are affected:

  o WinProladder: Versions 3.30 and prior

3.2 VULNERABILITY OVERVIEW

3.2.1 USE AFTER FREE CWE-416

A use after free vulnerability may be exploited when a valid user opens a
malformed project file, which may allow arbitrary code execution.

CVE-2021-38438 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 ).

3.2.2 OUT-OF-BOUNDS WRITE CWE-787

The affected product lacks proper validation of user-supplied data when parsing
project files, which could result in an out-of-bounds write. An attacker could
leverage this vulnerability to execute arbitrary code.

CVE-2021-38426 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 ).

3.2.3 UNEXPECTED SIGN EXTENSION CWE-194

The affected product lacks proper validation of user-supplied data when parsing
project files, which could result in an unexpected sign extension. An attacker
could leverage this vulnerability to execute arbitrary code.

CVE-2021-38434 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 ).

3.2.4 STACK-BASED BUFFER OVERFLOW CWE-121

The affected product lacks proper validation of user-supplied data when parsing
project files, which could result in a stack-based buffer overflow. An attacker
could leverage this vulnerability to execute arbitrary code.

CVE-2021-38430 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 ).

3.2.5 IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER
CWE-119

The affected product lacks proper validation of user-supplied data when parsing
project files, which could result in a memory-corruption condition. An attacker
could leverage this vulnerability to execute arbitrary code in the context of
the current process.

CVE-2021-38436 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 ).

3.2.6 IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER
CWE-119

The affected product lacks proper validation of user-supplied data when parsing
project files, which could result in a heap-corruption condition. An attacker
could leverage this vulnerability to execute code in the context of the current
process.

CVE-2021-38442 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 ).

3.2.7 OUT-OF-BOUNDS READ CWE-125

The affected product is vulnerable to an out-of-bounds read, which may allow an
attacker to read unauthorized information.

CVE-2021-38440 has been assigned to this vulnerability. A CVSS v3 base score of
3.3 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:N/UI:R/S:U/
C:L/I:N/A:N ).

3.3 BACKGROUND

  o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
  o COUNTRIES/AREAS DEPLOYED: Worldwide
  o COMPANY HEADQUARTERS LOCATION: Taiwan

3.4 RESEARCHER

xina1i and Natnael Samson (@NattiSamson), working with Trend Micro's Zero Day
Initiative, reported these vulnerabilities to CISA.

4. MITIGATIONS

FATEK Automation has not responded to requests to work with CISA to mitigate
these vulnerabilities. Users of these affected products are invited to contact
FATEK customer support for additional information.

CISA also recommends users take the following measures to protect themselves
from social engineering attacks:

  o Do not click web links or open unsolicited attachments in email messages.
  o Refer to Recognizing and Avoiding Email Scams for more information on
    avoiding email scams.
  o Refer to Avoiding Social Engineering and Phishing Attacks for more
    information on social engineering attacks.

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.

For any questions related to this report, please contact the CISA at:

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

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

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