Cybersecurity researchers have spotted a new Linux malware downloader that targets poorly defended Linux servers with cryptocurrency miners and DDoS IRC bots.
Researchers from ASEC discovered the attack after the Shell Script Compiler (SHC) used to create the downloader was uploaded to VirusTotal. Apparently, Korean users were the ones uploading the SHC, and it’s Korean users who are targets, as well.
Further analysis has shown that the threat actors are going after poorly defended Linux servers, brute-forcing their way into administrator accounts over SSH.
Once they make their way in, they’ll either install a cryptocurrency miner, or a DDoS IRC bot. The miner being deployed is XMRig, arguably the most popular cryptocurrency miner among hackers. It uses the computing power of a victim’s endpoints to generate Monero, a privacy-oriented cryptocurrency whose transactions are seemingly impossible to track, and whose users are allegedly impossible to identify.
For the DDoS IRC bot, the threat actors can use it to run commands such as TCP Flood, UDP Flood, or HTTP Flood. They can run port scanning, Nmap scanning, kill various processes, clean up the logs, and more.
“Because of this, administrators should use passwords that are difficult to guess for their accounts and change them periodically to protect the Linux server from brute force attacks and dictionary attacks, and update to the latest patch to prevent vulnerability attacks,” ASEC said in its report.
“Administrators should also use security programs such as firewalls for servers accessible from outside to restrict access by attackers.”
Linux systems are being constantly bombarded with malicious deployments, most often ransomware and cryptojacking.
A VMware report from February 2022 said the continued success of Linux services in the digital infrastructure and cloud industries, as well as the fact that most anti-malware and cybersecurity solutions are focused on protecting Windows-based devices, put Linux on thin ice.
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