A new Linux (opens in new tab) malware has been discovered that is capable of avoiding detection by antivirus programs, steals sensitive data from compromised endpoints (opens in new tab) and infects all processes running on a device.
Cybersecurity researchers from Intezer Labs say the malware (opens in new tab), dubbed OrBit, modifies the LD_PRELOAD environment variable, allowing it to hijack shared libraries and, consequently, intercept function calls.
“The malware implements advanced evasion techniques and gains persistence on the machine by hooking key functions, provides the threat actors with remote access capabilities over SSH, harvests credentials, and logs TTY commands,” Intezer Labs researcher Nicole Fishbein explained.
Hiding in plain sight
“Once the malware is installed it will infect all of the running processes, including new processes, that are running on the machine.”
Up until only recently, most antivirus solutions did not treat OrBit dropper, or payload, as malicious, the researchers said but added that now, some anti-malware service providers do identify OrBit as malicious.
“This malware steals information from different commands and utilities and stores them in specific files on the machine. Besides, there is an extensive usage of files for storing data, something that was not seen before,” Fishbein concluded.
“What makes this malware especially interesting is the almost hermetic hooking of libraries on the victim machine, that allows the malware to gain persistence and evade detection while stealing information and setting SSH backdoor.”
Threat actors have been quite active on the Linux platform lately, BleepingComputer has found. Besides OrBit, the recently discovered Symbiote malware also uses the LD_PRELOAD directive to load itself into running processes. It acts as a system-wide parasite, the publication claims, adding that it leaves no sign of infection.
BPFDoor is a similar malware strain, as well. It targets Linux systems and hides by using the names of common Linux daemons. This helped it stay under antivirus radars for five years.
Besides these two, there is also Syslogk, capable of both loading, and hiding, malicious programs. As revealed by cybersecurity researchers from Avast, the rootkit malware is based on an old, open-sourced rootkit called Adore-Ng. It’s also in a relatively early stage of (active) development, so whether or not it evolves into a full-blown threat, remains to be seen.
