Siemens has workarounds and mitigations to handle an uncontrolled resource consumption vulnerability in its SCALANCE X switches, according to a report with the Cybersecurity and Infrastructure Security Agency (CISA).
Successful exploitation of this remotely exploitable vulnerability, discovered by Younes Dragoni from Nozomi Networks, could cause a denial-of-service condition.
The following versions of SCALANCE X switches suffer from the issue:
• SCALANCE X-200: All versions
• SCALANCE X-200IRT: All versions
• SCALANCE X-200RNA: All versions
In the vulnerability, an attacker may send large message packages repeatedly to the telnet service, which may allow a denial-of-service condition.
CVE-2019-10942 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 8.6.
The product sees use in the chemical, critical manufacturing, energy, food and agriculture, and water and wastewater systems sectors. It also sees action on a global basis.
No known public exploits specifically target this vulnerability. However, an attacker with low skill level could leverage the vulnerability.
Siemens identified the following specific workarounds and mitigations users can apply to reduce the risk:
1. Disable telnet service on affected devices. Users should use SSH instead.
2. Restrict network access to Port 23/TCP of the device.
Siemens recommends users configure their environment according to Siemens’ operational guidelines for industrial security and follow the recommendations in the product manuals.
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For more information on the vulnerability and more detailed mitigation instructions, see Siemens security advisory SSA-100232.