ICS-CERT revealed last week that Westermo industrial switches use the same hardcoded SSL private keys, allowing malicious actors to intercept communications and gain unauthorized access to devices.
Westermo is a Sweden-based company that designs and manufactures industrial-grade communications products for mission-critical systems. The firm’s solutions are used across the world in sectors such as transport, water, energy supplies, mining and petrochemical.
According to ICS-CERT, researcher Neil Smith discovered that the SSL keys used by Westermo industrial switches to secure communications are hardcoded and shared across devices.
Since it cannot be changed, a malicious actors who obtains the key can intercept and decrypt communications via a man-in-the-middle (MitM) attack. An attacker could intercept login credentials and leverage the information to gain access to a vulnerable device.
An attacker with low skill can exploit this flaw, but only if they first manage to launch a successful MitM attack.
The vulnerability, which has been assigned the identifier CVE-2015-7923 and a CVSS score of 9.0, affects devices running versions 4.18 and earlier of WeOS, the operating system that powers Westermo’s hardware platforms. The list of affected product lines includes Falcon, Wolverine, Lynx, Viper and RedFox.
The vendor has released an update that allows users to change the problematic certificate in the web interface of the affected devices. The company is also working on a fix, which will likely be included in WeOS 4.19, to automate the changing of the key.
In the meantime, users have been advised to update WeOS to the latest version and upload a custom certificate. Detailed instructions for replacing the default certificate have been provided. The company recommends that customers avoid self-signed certificates and either completely disable web access to the devices or limit access to secure networks.