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Critical Vulnerabilities Expose Siemens LOGO! Controllers to Attacks

Siemens’ LOGO! programmable logic controllers (PLCs) are affected by critical vulnerabilities that can be exploited remotely to launch denial-of-service (DoS) attacks and modify the device’s configuration.

According to Siemens, the vulnerabilities impact all versions of its LOGO!8 BM devices, which are designed for basic control tasks. SIPLUS versions, which are meant for use in extreme conditions, are also affected.

The German industrial giant has yet to release patches for the vulnerabilities, which have been described as missing authentication issues, but it has told customers that they can reduce the risk of exploitation by applying defense-in-depth measures.

Siemens says an unauthenticated attacker who has network access to TCP port 135 can exploit the vulnerabilities to read and modify a device’s configuration and obtain project files, without user interaction.

While the advisories published this week by Siemens and CISA mention a single vulnerability, Cisco’s Talos threat intelligence and research group, which the vendor has credited for the findings, says there are actually three missing authentication flaws tracked under the same CVE identifier, CVE-2020-7589.

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According to advisories published by Talos, all three vulnerabilities are related to the TDE text display functionality of LOGO! products, and they can all be exploited by sending specially crafted packets to the targeted system. Talos has released technical information on what these payloads look like.

The company says two of the flaws allow an attacker to delete information on the device, causing a denial-of-service (DoS) condition. The third bug can be exploited to upload or overwrite files on the SD card, which, Talos says, can impact the device’s integrity and availability.

Related: Siemens Industrial Devices Affected by 'SegmentSmack' Linux Kernel Flaw

Related: Siemens Addresses Vulnerabilities in LOGO, SINAMICS Products

Related: Siemens Patches Serious DoS Vulnerabilities in Several Products

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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.