Security researchers observed an attack campaign that is targeting Linux servers to install samples of SpeakUp, a new backdoor Trojan.

According to Check Point Research, the campaign is currently targeting servers in East Asia and Latin America. The attack begins with the exploitation of CVE-2018-20062, a reported vulnerability affecting ThinkPHP. The campaign then uses command injection techniques to upload a PHP shell, which is responsible for delivering and executing the SpeakUp Trojan as a Perl backdoor.

Upon execution, SpeakUp continuously communicates with its command and control (C&C) server to receive a variety of instructions. It can use the newtask command to execute arbitrary code or execute a file from a remote server, for example. This ability enables SpeakUp to deliver additional backdoors, each of which comes equipped with a Python script designed to scan and infect more Linux servers within its internal and external subnets.

Furthermore, the Trojan can leverage the newconfig command to update the configuration file for XMRig, a cryptocurrency miner that it serves to listening infected servers.

Linux Servers Under Attack

SpeakUp isn’t the only malware targeting Linux servers. On the contrary, these IT assets are under attack from a range of malicious software.

In December 2018, Slovakian security firm ESET identified 21 Linux malware families that serve as OpenSSH backdoors. Around the same time, Anomali Labs unveiled its discovery of Linux Rabbit and Rabbot, two malware families served by a campaign targeting Linux servers in Russia, South Korea, the U.K. and the U.S. that are both capable of installing crypto-miners.

Also in December, Bleeping Computer learned of a new campaign that had leveraged unsecured Intelligent Platform Management Interface (IPMI) cards to infect Linux servers with JungleSec ransomware.

How to Defend Against the SpeakUp Trojan

Security professionals can help defend against malware like SpeakUp by utilizing a unified endpoint management (UEM) tool to monitor assets such as Linux servers for malicious activity. Experts also recommend practicing timely patch management to defend endpoints against cryptocurrency miners, and investing in education and role-based training to help cultivate a security-aware workforce.