Pierluigi Paganini October 14, 2019

Cisco Talos experts discovered nearly a dozen flaws affecting some of the models of Schneider Electric’s Modicon programmable logic controllers.

Talos experts discovered 11 security flaws affecting some models of Schneider Electric’s Modicon programmable logic controllers.

Affected models are Modicon M580, M340, BMENOC 0311, BMENOC 0321, Quantum, Premium, and Modicon BMxCRA and 140CRA.

The unique model that is affected by all the vulnerabilities is the M580 PLC. The flaws affect the implementation of the Modbus, FTP and TFTP protocols, and the REST API. Schneider Electric published four advisories to address the vulnerabilities.

The vulnerabilities in the TFTP and the REST API were tracked with codes between CVE-2019-6841 and CVE-2019-6851, an attacker could exploit them by sending specially crafted requests to the impacted devices.

The vulnerability in the TFTP protocol, tracked as CVE-2019-6851, is a File and Directory Information Exposure issue that could cause the disclosure of information from the controller when using this protocol.

REST API is affected by three vulnerabilities, CVE-2019-6848, CVE-2019-6849, CVE-2019-6850.

CVE-2019-6848 is an uncaught exception issue that could be exploited to cause a Denial of Service condition by sending specific data on the REST API of the controller/communication module.

CVE-2019-6849 is an Information Exposure vulnerability that could cause the disclosure of sensitive information when using specific Modbus services provided by the REST API of the controller/communication module.

CVE-2019-6850 is another Information Exposure vulnerability that could cause the disclosure of sensitive information when reading specific registers with the REST API of the controller/communication module.

Most of the vulnerabilities in the FTP protocol (CVE-2019-6841, CVE-2019-6842, CVE-2019-6843, CVE-2019-6844, CVE-2019-6846, CVE-2019-6847) could be exploited to cause a DoS condition.

Talos researchers reported the vulnerabilities to Schneider Electric in May and July. The company’s advisories provide a series of recommendations for preventing the exploitation of the issues. Talos blog post also includes SNORT rules to detect exploitation attempts.

Pierluigi Paganini

(SecurityAffairs – Schneider Electric Modicon, hacking)

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