A new version of it Mirai Malware, created by hackers, exploits the vulnerability to execute remote code (CVE-2020-9054), which was recently repaired in Appliances storage associated with the Zyxel Network (NAS).
The vulnerability has been described as "critical" and rated at 9,8 CVE. This error allows the Mukashi botnet to perform brute force attacks on logins using different combinations of default credentials.
Zyxel NAS devices running up to 5.21 firmware versions are vulnerable to exploiting this new variant of malware.
The researchers discovered the vulnerability on March 12, 2020, when the intruder attempted to download a shell script to the tmp directory, execute the downloaded script, and remove its data from the vulnerable device.
Mukashi is also able to launch an attack DDOS on the infected machine, receiving the command from the C2 server.
How does it work;
Hackers first detect the TCP port of 23 random hosts belonging to the target network. For this purpose they use the Mukashi bot and attack brute force on logins, using default credentials. They then report the successful connection attempt to the C2 server.
After successful execution, the malware displays the message "Protect your device against further infections" on the console and commits to TCP port 23448 to ensure that this action is performed before proceeding to the intended function.
Researchers recommend that users download the latest version firmware. They are also urged to set a complex password to prevent brute force attacks.