Vulnerabilities affecting Linear building access control products, including a security flaw that has been exploited in the wild, have been patched nearly five years after their initial disclosure.
In May 2019, at SecurityWeek’s ICS Cyber Security Conference, Gjoko Krstic, a researcher who at the time worked for industrial cybersecurity firm Applied Risk, disclosed information on more than 100 vulnerabilities found in building management and access control systems from Nortek, Prima Systems, Optergy, and Computrols.
Nortek stood out at the time because it was the only vendor that had not released patches. It claimed to have released fixes, but Krstic said at the time that the vendor had not given him the opportunity to send over the actual vulnerability details.
Over 2,500 internet-exposed instances of the company’s Linear eMerge access control product were identified when the vulnerabilities were disclosed in 2019.
Less than one year later, in February 2020, SonicWall reported that one of the vulnerabilities found by Krstic, a critical unauthenticated remote code execution bug tracked as CVE-2019-7256, had been exploited in attacks.
The security firm was seeing tens of thousands of daily attempts to exploit the vulnerability in an effort to infect devices with a piece of malware that would allow cybercriminals to launch DDoS attacks. Over 2,300 potentially affected devices had still been exposed to the internet.
In July 2020, the US cybersecurity agency CISA published an advisory to inform customers that Nortek had released patches for five of the Linear eMerge vulnerabilities found by Krstic, but the list did not include the exploited CVE-2019-7256.
Nortek Security & Control was acquired by smart home, security and building automation solutions firm Nice in 2021, but it apparently took until 2023 for the vulnerabilities to emerge on Nice’s radar.
In May 2023, the vendor published a security bulletin saying that it had become aware that some of the Linear telephone entry (intercom) products had been compromised. However, no CVE identifiers were mentioned in the bulletin.
The company urged customers to increase network security and remove the impacted system from the internet until a permanent solution is provided. Customers whose devices had been hacked were offered a firmware recovery kit at no cost.
In late June 2023, Nice published a second security bulletin, informing customers of Linear eMerge E3 series door access control products about the availability of a firmware update that should address some unspecified vulnerabilities.
CISA published a new advisory describing a dozen Linear eMerge E3 series vulnerabilities on March 5, 2024, warning that they can allow a remote attacker to gain full system access. All of the security holes have 2019 CVEs and the list includes CVE-2019-7256, the vulnerability exploited in the wild.
CISA said the latest firmware update should address the flaws, but it’s unclear exactly when the patches were released. Krstic told SecurityWeek on Monday that Nice informed CISA in September 2023 that it had still been working on guidance for securing impacted devices. The researcher said he never received confirmation of a patch being developed or tested.
Contacted by SecurityWeek, Nice said it takes the security of its products very seriously and confirmed releasing firmware patches.
“After we were notified of the vulnerabilities referenced in the CISA advisory, we immediately initiated an investigation to assess the validity and potential implications for our products and customers,” said Paul Williams, managing director of Nice’s home management business unit.
“Following our investigation, we learned that these vulnerabilities are limited to telephone entry systems that were deployed outside the protection of a firewall. Furthermore, we have received no reports of sensitive data having been accessed as a result of these issues.
“To mitigate these vulnerabilities, we immediately alerted our vendors and customers and initiated a remediation plan, including only installing our telephone entry system behind a firewall. We have since released firmware updates specifically designed to fix the vulnerabilities,” Williams added.
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