Three high-impact security vulnerabilities have been disclosed in APC Smart-UPS devices that could be abused by remote adversaries as a physical weapon to access and control them in an unauthorized manner.

TLStorm consists of a trio of critical flaws that can be triggered via unauthenticated network packets without requiring any user interaction, meaning it’s a zero-click attack, with two of the issues involving a case of faulty TLS handshake between the UPS and the APC cloud -.

Successful exploitation of any of the flaws could result in remote code execution attacks on vulnerable devices, which in turn could be weaponized to tamper with the operations of the UPS to physically damage the device or other assets connected to it.

“By using our RCE vulnerability we were able to bypass the software protection and let the current spike periods run over and over until the DC link capacitor heated up to ~150 degrees celsius, which caused the capacitor to burst and brick the UPS in a cloud of electrolyte gas, causing collateral damage to the device,” the researchers explained.

To make matters worse, the flaw in the firmware upgrade mechanism could be leveraged to plant a malicious update on UPS devices, enabling the attackers to establish persistence for extended periods of time and use the compromised host as a gateway for further attacks.

“Abusing flaws in firmware upgrade mechanisms is becoming a standard practice of APTs, as has been recently detailed in the analysis of the Cyclops Blink malware, and improper signing of firmwares of embedded devices is a recurring flaw in various embedded systems,” the researchers said.