In the third quarter of 2026, multiple attack campaigns targeted poorly managed Linux SSH servers using brute force, dictionary attacks, and vulnerability exploits. Attackers deployed ShellBot, a Perl-based DDoS bot with port scanning and UDP flooding capabilities. A complex attack chain involved a user-mode rootkit loaded via /etc/ld.so.preload, which then deployed the XMRig cryptocurrency miner disguised as a bash process using the XHide concealment tool. Additionally, the Fisieredoor backdoor was used to execute commands and install SSH brute-force tools such as goauto and tsm-family that systematically targeted systems with credential lists. Organizations are advised to implement strong password policies, maintain regular patching schedules, and enforce access controls on externally exposed SSH infrastructure.
Analysis of attacks against Linux SSH servers during Q1 2026 reveals P2PInfect worm as the dominant threat, representing 70.3% of all attack sources. DDoS botnets including Mirai, XMRig, Prometei, and CoinMiner were identified as primary threats. A notable campaign involved installing V2Ray proxy tools on compromised systems, attributed to a suspected Chinese threat actor. Attackers employed SSH brute-force techniques to gain access, executed reconnaissance commands to assess system information, and deployed V2Ray for proxy node operations. The campaign targeted poorly secured SSH servers with weak credentials, emphasizing the need for strong password policies, access controls, and network monitoring to detect unusual outbound connections and proxy-related activities.
Unit 42 researchers identified a new wave of Prometei botnet attacks in March 2025. The malware, which includes Linux and Windows variants, allows remote control of compromised systems for cryptocurrency mining and credential theft. Prometei is actively developed, incorporating new modules and methods, including a backdoor for various malicious activities. It uses a domain generation algorithm for C2 infrastructure and self-updating features for evasion. The article analyzes versions three and four of the Linux variant, highlighting differences from version two. Prometei's modular architecture makes it highly adaptable, with components for brute-forcing credentials, exploiting vulnerabilities, mining cryptocurrency, stealing data, and C2 communication. The botnet's primary goal is Monero mining, but it also has secondary capabilities like credential theft and deploying additional malware payloads.
