7.5 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8 High
AI Score
Confidence
High
0.072 Low
EPSS
Percentile
94.1%
CVSS v3 10.0
**ATTENTION:**Exploitable remotely/low skill level to exploit
**Vendor:**Rockwell Automation
**Equipment:**RSLinx Classic
**Vulnerability:**Stack-based Buffer Overflow
Successful exploitation of this vulnerability could allow a remote attacker to execute arbitrary code on the target device.
The following versions of RSLinx Classic, PLC communications software, are affected:
3.2.1 STACK-BASED BUFFER OVERFLOW CWE-121
An input validation issue in a .dll file of RSLinx Classic where the data in a Forward Open service request is passed to a fixed size buffer, allowing an attacker to exploit a stack-based buffer overflow condition.
CVE-2019-6553 has been assigned to this vulnerability. A CVSS v3 base score of 10.0 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H).
Rockwell Automation (working with Tenable) reported this vulnerability to CISA.
Rockwell Automation has released patches to address earlier versions of RSLinx Classic including v3.60, v3.70, v3.80, v3.81, v3.90, v4.00.01, v4.10. These patches can be found at Knowledgebase Article ID: 1084828
<https://rockwellautomation.custhelp.com/app/answers/detail/a_id/1084828>
Rockwell Automation has also stated that users may disable Port 44818 in RSLinx Classic if it is not utilized during system operation. To disable Port 44818, go to Options in RSLinx Classic. Then in the General tab of the Options pop-up, uncheck the option “Accept UDP Messages on Ethernet Port”.
Port 44818 is needed only when a user wants to utilize unsolicited messages. To check if you are using unsolicited messages, go to the “DDE/OPC” dropdown in RSLinx Classic. Select Topic Configuration and then go to the Data Collection tab in the Topic Configuration pop-up. If the “Unsolicited Messages” checkbox is marked, then Port 44818 is being used in the application.
NOTE: In RSLinx Classic 4.10 or later, “Accept UDP Messages on Ethernet Port” checkbox is unchecked by default.
For more information please see the Rockwell Automation security advisory found at:
<https://rockwellautomation.custhelp.com/app/answers/detail/a_id/1085038>
NCCIC recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:
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 this vulnerability.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-6553
cwe.mitre.org/data/definitions/121.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
rockwellautomation.custhelp.com/app/answers/detail/a_id/1084828
rockwellautomation.custhelp.com/app/answers/detail/a_id/1085038
twitter.com/CISAgov
twitter.com/intent/tweet?text=Rockwell%20Automation%20RSLinx%20Classic+https://www.cisa.gov/news-events/ics-advisories/icsa-19-064-01
www.dhs.gov
www.dhs.gov/foia
www.dhs.gov/performance-financial-reports
www.facebook.com/CISA
www.facebook.com/sharer/sharer.php?u=https://www.cisa.gov/news-events/ics-advisories/icsa-19-064-01&title=Rockwell%20Automation%20RSLinx%20Classic
www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
www.instagram.com/cisagov
www.linkedin.com/company/cybersecurity-and-infrastructure-security-agency
www.linkedin.com/sharing/share-offsite/?url=https://www.cisa.gov/news-events/ics-advisories/icsa-19-064-01
www.oig.dhs.gov/
www.surveymonkey.com/r/CISA-cyber-survey?product=https://www.cisa.gov/news-events/ics-advisories/icsa-19-064-01
www.usa.gov/
www.whitehouse.gov/
www.youtube.com/@cisagov
mailto:?subject=Rockwell%20Automation%20RSLinx%20Classic&body=www.cisa.gov/news-events/ics-advisories/icsa-19-064-01
7.5 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8 High
AI Score
Confidence
High
0.072 Low
EPSS
Percentile
94.1%