New Linux Malware is Nearly Undetectable

Digital security specialists insist a new form of Linux malware is discrete to the point that it is almost impossible to identify. The malware empowers digital criminals to steal login credentials, providing those miscreants with remote access along with rootkit functionality.

How Does Linux Malware Work?

Linux malware is similar to a parasite. The malware infects targeted computers, similar to how a parasite sucks blood from its host. Digital security specialists recently revealed the details of the malware with The BlackBerry Research and Intelligence Team. The researchers have been tracking the malware for more than a year. Linux malware first appeared in the late fall of 2021.

The malware relies on the libc read function to steal credentials. The credentials are initially encrypted with an embedded key and transmitted to a designated file. The credentials are stolen for use in the context of local access and also for exfiltration through encoding and transmitting the data through DNS address record requests. The data ends up in a controlled domain name.

The malware uses Pluggable Authentication Module functions, or PAM functions for short, to obtain remote access to the compromised machine, laying the groundwork for the machine's authentication with services such as Secure Shell that use PAM. The malware reviews the password, comparing it to a hardcoded password each time a service attempts to authenticate a user with PAM. Once authentication occurs, the malware empowers the hacker to scan the environment for a variable to obtain root privileges, change the user, alter the group ID, and clear the variable prior to execution through system command.

What is the Name of the Malware?

The malware went without a name for a period of time. However, those who identified and analyzed the malware eventually named it "Symbiote" in reference to organisms that symbiotically live with other organisms. 

The name was chosen to symbolize the manner in which the malware functions.

How is Symbiote Different From Other Malware?

The malware is different from other Linux malware in that it infects processes that are running to cause significant damage to machines that have been infected. Rather than functioning as an executable file that is standalone and runs to infect targeted machines, the malware functions as a shared object library, or SO for short. The malware is loaded onto the running processes and infects the computer, similar to a parasite.

The party responsible for the threat can conduct all sorts of harmful activity after the malware infection occurs. The malware infects the running processes, can perform rootkit functionality, allow for remote access to the machine, steals login credentials, and more. The malware even has a backdoor for the digital miscreant to log in as a chosen user on the machine using a password that is hardcoded, ultimately setting the stage for the execution of commands that would otherwise be restricted to users with elevated administrator privileges.

How Does Symbiote Avoid Detection?

Symbiote sidesteps tools designed to identify digital threats, making it challenging for computer users to even know if the malware is present. The malware's evasive tactics are used before, during, and after the infection. Symbiote is clandestine and mysterious to the point that digital forensics specialists could not determine if it is used in broad, overarching attacks or specific, highly targeted attacks. In fact, running live forensics on the compromised machine might not identify the infections as the malware conceals the network artifacts, processes, files, and other identifiable information linked to the malware.