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[R1] 3S CODESYS PLCWinNT Runtime Service NULL Pointer Dereference Remote DoS

High

Synopsis

CODESYS Runtime, a runtime system that "turns any embedded or PC based device into a full-fledged IEC 61131-3 controller", is vulnerable to a remote denial of service attack. The issue is due to the PLCWinNT Runtime service that runs on TCP port 1200 not properly sanitizing user-supplied input. By sending a crafted request, a remote attacker can trigger a NULL pointer dereference, crashing the service. Without the service running, the functionality of the device is effectively gone. Tenable has created a working exploit that demonstrates the issue, but will not be releasing it.

Note that this Runtime system may be used in additional software.

Solution

Upgrade the PLCWinNT Runtime software to version 2.4.7.48, or upgrade to CODESYS 2.3.9.48 which includes the updated Runtime.

Disclosure Timeline

2015-08-01 - Issue discovered
2015-08-04 - ICS-CERT informed, asked to coordinate and assign CVE
2015-08-10 - Tenable pinged ICS-CERT
2015-08-10 - ICS-CERT reply, ICS-VU-607305 assigned
2015-08-26 - ICS-CERT requests PoC on behalf of vendor, PoC sent
2015-08-27 - ICS-CERT relays PoC to vendor
2015-09-08 - Tenable pinged ICS-CERT re: CVE assignment
2015-10-12 - ICS-CERT indicates S3 plans to post a fix on 2015-10-15. Provides draft advisory with CVE ID for review.
2015-10-12 - Provided feedback on draft advisory
2015-10-15 - Issue disclosed via ICS-CERT, Vendor advisory, Tenable advisory (go coordination!)

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