Pierluigi Paganini November 22, 2018

These Mirai variants are the first one that doesn’t target Internet of Things devices, the bot was specifically developed to target Linux servers.

The Hadoop YARN is vulnerability is a command injection flaw that could be exploited by attackers to remotely execute arbitrary shell commands on a vulnerable server.

The new versions don’t implement worm-like spreading abilities, instead, threat actors leverage exploits to spread the malware.

Netscout observed tens of thousands of exploit attempts daily targeting it honeypots, in November attackers attempted to deliver some 225 unique malicious payloads exploiting the Hadoop YARN vulnerability.

One of the variants spotted by the experts labeled itself as VPNFilter, even if it is not linked with the infamous VPNFilter bot that infected more than a half-million small and home office routers in May.

“ASERT has been monitoring exploit attempts for the Hadoop YARN vulnerability in our honeypot network and found a familiar, but surprising payload – Mirai. These versions of Mirai behave much like the original but are tailored to run on Linux servers and not underpowered IoT devices.” reads the analysis published by the experts.

“Mirai botmasters that target Linux servers no longer need to tailor their malware for strange architectures, they assume their targets are using x86.”

The specific Mirai variant only delivers the x86 variant of the bot because much Hadoop YARN services are running on x86 Linux servers.

Other IoT Mirai variants first examine the victim device in order to deliver the proper executable (x86, x64, ARM, MIPS, ARC, etc.=

Vulnerable Linux servers are a privileged target for attackers that attempt to compromise them to carry out malicious activities by exploiting their hardware resources that are greater than IoT ones.

“The limited number of sources we’ve seen continually scanning for the Hadoop YARN vulnerability may indicate this activity is the work of a small group of attackers. Their goal is clear – to install the malware on as many devices as possible.” concluded the experts.

“Once gaining a foothold, Mirai on a Linux server behaves much like an IoT bot and begins brute-forcing telnet usernames and passwords. What’s different now is that among the small, diminutive devices in the botnet lurk fully powered Linux servers.”

Pierluigi Paganini

(Security Affairs – Mirai, Linux)

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