March 23, 2020 By Shane Schick 2 min read

Network-attached storage (NAS) devices are being targeted by Mukashi, a variant of the Mirai malware, in an effort to launch large-scale distributed denial-of-service (DDoS) attacks, researchers warn.

The attacks, which Palo Alto Networks says have already been spotted in the wild, use brute-force techniques against default credentials in order to access NAS products from Zyxel running firmware 5.21.

Mukashi is attempting to take advantage of a critical vulnerability that would allow cybercriminals to execute code. Researchers said Mukashi, like Mirai, could then be used to aim DDoS attacks at a particular target, or several targets.

Phony Protection Messages

Those who monitor consoles during a Mukashi attack will be greeted with the message, “Protecting your device from further infections.”

In reality, the botnet is stealthily decoding strings such as credentials and command-and-control (C&C) commands before making brute-force attempts to see if default credentials are based on commonly used passwords. Having scanned TCP port 23 on random hosts, Mukashi ensures only a single instance is running on a machine following the initial infection by binding itself to TCP port 23448.

Researchers said Mukashi’s capabilities were equal to that of Mirai, despite some differences in code. Given the latter’s success in causing shutdowns across the internet in 2016, the report said Mukashi should be taken as a serious threat.

Patch, Then Check Passwords

The vulnerability Mukashi targets, also known as CVE-2020-9054, was only discovered in February, which means those behind the attacks will probably be trying to find those who haven’t already dealt with it.

Zyxel has already issued a patch for the flaw, so the first step is ensuring it’s been applied if your organization runs any of those NAS devices or connects to them.

Next, take a second look at your default passwords and make sure they’re not so simple or weak that they could easily be guessed via automation. This is more important than ever as the internet of things (IoT) expands and IoT devices become more essential to organizations in a wide variety of industries.

Mirai was a successful piece of malware — Mukashi is just more proof that cybercriminals will continue to learn from it.

More from

IBM identifies zero-day vulnerability in Zyxel NAS devices

12 min read - While investigating CVE-2023-27992, a vulnerability affecting Zyxel network-attached storage (NAS) devices, the IBM X-Force uncovered two new flaws, which when used together, allow for pre-authenticated remote code execution. Zyxel NAS devices are typically used by consumers as cloud storage devices for homes or small to medium-sized businesses. When used together, the flaws X-Force discovered allow a remote attacker to execute arbitrary code on the device with superuser permissions and without requiring any credentials. This results in complete control over the…

What cybersecurity pros can learn from first responders

4 min read - Though they may initially seem very different, there are some compelling similarities between cybersecurity professionals and traditional first responders like police and EMTs. After all, in a world where a cyberattack on critical infrastructure could cause untold damage and harm, cyber responders must be ready for anything. But are they actually prepared? Compared to the readiness of traditional first responders, how do cybersecurity professionals in incident response stand up? Let’s dig deeper into whether the same sense of urgency exists…

Unified endpoint management for purpose-based devices

4 min read - As purpose-built devices become increasingly common, the challenges associated with their unique management and security needs are becoming clear. What are purpose-built devices? Most fall under the category of rugged IoT devices typically used outside of an office environment and which often run on a different operating system than typical office devices. Examples include ruggedized tablets and smartphones, handheld scanners and kiosks. Many different industries are utilizing purpose-built devices, including travel and transportation, retail, warehouse and distribution, manufacturing (including automotive)…

Stealthy WailingCrab Malware misuses MQTT Messaging Protocol

14 min read - This article was made possible thanks to the hard work of writer Charlotte Hammond and contributions from Ole Villadsen and Kat Metrick. IBM X-Force researchers have been tracking developments to the WailingCrab malware family, in particular, those relating to its C2 communication mechanisms, which include misusing the Internet-of-Things (IoT) messaging protocol MQTT. WailingCrab, also known as WikiLoader, is a sophisticated, multi-component malware delivered almost exclusively by an initial access broker that X-Force tracks as Hive0133, which overlaps with TA544. WailingCrab…

Topic updates

Get email updates and stay ahead of the latest threats to the security landscape, thought leadership and research.
Subscribe today