Nearly four years after Mirai first showed how ordinary Internet-connected devices could be turned into remotely controlled attack systems, variants of the malware continue to surface with troubling regularity.
This week researchers from Trend Micro reported discovering a brand-new Mirai variant designed to exploit a set of previously disclosed vulnerabilities in routers, IP cameras, DVRs, and other products from multiple vendors, including Comtrend, D-Link, MV Power, Symantec, and AVTech.
Among the nine vulnerabilities the malware can exploit is a remote code execution flaw in a router model from Comtrend (CVE-2020-10173) that gives attackers a way to take control of the network managed by the router. Until this point, only proof-of-concept code for exploiting the flaw — first disclosed in March — had been available.
Another relatively new vulnerability exploited by the latest Mirai version is a remote code execution issue in Netlink GPON Router 1.0.11 that at least one other Internet of Things (IoT) botnet — a variant of Gafgyt/Bashlite — has already exploited. The remaining seven vulnerabilities are all older ones previously exploited by other malware.
"The vulnerabilities used by this Mirai variant consist of a combination of old and new that help cast a wide net encompassing different types of connected devices," said Trend Micro in a blog Monday. "The nine vulnerabilities used in this campaign affect specific versions of IP cameras, smart TVs, and routers, among others."
The new Mirai version is at least the fourth that security researchers have come across just this year. In February, researchers at Trend Micro reported finding two Mirai variants — SORA and UNSTABLE — that targeted a security weakness in a video surveillance storage device from Rasilient. In March, bug hunters at Palo Alto Networks reported on Mukashi, a Mirai variant that targeted Zyxel network-attached storage (NAS) devices.
Attackers have used such variants to compromise vulnerable IoT devices and assemble them into botnets for launching distributed denial-of-service attacks, distributing malware, or carrying out other malicious activities.
While the latest Mirai version is capable of exploiting nine different vulnerabilities, some previous variants have incorporated exploits for far more. A version of the Echobot Mirai variant last December, for instance, packaged exploits for as many as 71 unique vulnerabilities, 13 of which were previously unexploited when the malware was released.
Myla Pilao, director of security research at Trend Micro, points to a couple of of reasons for attackers' continuing interest in building Mirai-like malware. The first, she says, is the growth in the number of IoT devices and the number of people using them, especially now with so many working from home.
The second reason is that many IoT devices continue to be vulnerable or are poorly secured and therefore easy attack targets, Pilao says. In many cases, attackers have been able to force their way into routers, IP cameras, smart TVs, and other Internet-connected devices by brute-force guessing passwords or by taking advantage of insecure configurations.
The trend highlights the need for organizations to pay closer attention to the procurement of IoT devices, she notes. "Implement [a] strict protocol in the purchase, test, deployment, and adoption of these devices into your network," Pilao says.
Make sure also to implement proper authentication and credential management processes and use encryption where possible.
"Develop a clear process for quality patch management and deployment," Pilao says. With more people working from home, organizations need to ensure that employees know how to properly patch vulnerable systems, she said.