Security Experts:

Flaw in Schneider PLC Programming Tool Allows Remote Attacks

Schneider Electric this week announced that an update for its EcoStruxure Machine Expert product patches a high severity vulnerability that can be exploited remotely to obtain sensitive data.

EcoStruxure Machine Expert - Basic, formerly known as SoMachine Basic, is a lightweight tool designed for programming Schneider’s Modicon M221 programmable logic controller (PLC).

Gjoko Krstic, a researcher at industrial cybersecurity firm Applied Risk, discovered recently that SoMachine Basic 1.6.0 build 61653, 1.5.5 SP1 build 60148, and likely earlier versions are impacted by an XML external entity (XXE) vulnerability that can be exploited to launch an out-of-band (OOB) attack.

Tracked as CVE-2018-7783, the vulnerability can be exploited by a remote and unauthenticated attacker to read arbitrary files on the targeted system. These files can include sensitive information, including passwords, user data, and details about the system.

For the attack to work, the hacker needs to convince the targeted user to open a specially crafted SoMachine Basic project or template file.

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“The vulnerability is triggered when input passed to the XML parser is not sanitized while parsing the XML project and/or template file,” Krstic wrote in an advisory.

The researcher also pointed out that in certain circumstances the flaw can also be exploited for arbitrary code execution and to cause a denial-of-service (DoS) condition.

Schneider Electric patched the vulnerability with the release of SoMachine Basic v1.6 SP1.

Last month, at SecurityWeek’s ICS Cyber Security Conference in Singapore, Krstic disclosed the details of a DoS vulnerability that affects safety controllers from several major vendors, including devices that are directly exposed to the Internet.

In January, Schneider Electric informed customers that its Floating License Manager, a tool that helps organizations manage licenses for Schneider products, contained code execution, open redirect and DoS vulnerabilities due to the use of a third-party component named Flexera FlexNet Publisher. The security holes were discovered in FlexNet Publisher in 2016 and 2017.

One week ago, Schneider published another advisory to inform customers that these flaws also impact PlantStruxure PES. ICS-CERT has also published an advisory on Thursday for the Floating License Manager issues.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.