New Linux Malware Steals Call Details from VoIP Softswitch Systems

Cybersecurity researchers have discovered an entirely new kind of Linux malware dubbed “CDRThief” that targets voice over IP (VoIP) softswitches in an attempt to steal phone call metadata.

“The primary goal of the malware is to exfiltrate various private data from a compromised softswitch, including call detail records (CDR),” ESET researchers said in a Thursday analysis.

“To steal this metadata, the malware queries internal MySQL databases used by the softswitch. Thus, attackers demonstrate a good understanding of the internal architecture of the targeted platform.”

Softswitches (short for software switches) are generally VoIP servers that allow for telecommunication networks to provide management of voice, fax, data and video traffic, and call routing.

ESET’s research uncovered that CDRThief targeted a specific Linux VoIP platform, namely the VOS2009 and 3000 softswitches from Chinese company Linknat, and had its malicious functionality encrypted to evade static analysis.

The malware starts off by attempting to locate the Softswitch configuration files from a list of predetermined directories with the goal of accessing the MySQL database credentials, which are then decrypted…