New ultra-stealthy Linux backdoor isn’t your everyday malware discovery

Researchers have unearthed a discovery that doesn’t occur all that often in the realm of malware: a mature, never-before-seen Linux backdoor that uses novel evasion techniques to conceal its presence on infected servers, in some cases even with a forensic investigation.

On Thursday, researchers from Intezer and The BlackBerry Threat Research & Intelligence Team said that the previously undetected backdoor combines high levels of access with the ability to scrub any sign of infection from the file system, system processes, and network traffic. Dubbed Symbiote, it targets financial institutions in Brazil and was first detected in November.

With the help of LD_PRELOAD, Symbiote will load before any other shared objects. That allows the malware to tamper with other library files loaded for an application. The image below shows a summary of all of the malware’s evasions techniques.