Vulnerability identifier: #VU35046

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-5636

CWE-ID: CWE-404

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
TwinCAT
Client/Desktop applications / Software for system administration

Vendor: Beckhoff

Description

The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.

When a Beckhoff TwinCAT Runtime receives a malformed UDP packet, the ADS Discovery Service shuts down. Note that the TwinCAT devices are still performing as normal. This issue affects TwinCAT 2 version 2304 (and prior) and TwinCAT 3.1 version 4204.0 (and prior).

Mitigation
Install update from vendor's website.

Vulnerable software versions

TwinCAT: 2.0 - 3.1

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External links
http://blog.rapid7.com/2019/10/08/r7-2019-32-denial-of-service-vulnerabilities-in-beckhoff-twincat-plc-environment-fixed/
http://download.beckhoff.com/download/Document/product-security/Advisories/advisory-2019-004.pdf

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.