Researchers have discovered a new threat called CDRThief that targets a VoIP system and attempts to steal call data records (CDRs).
The analysis of the malware revealed that it was created specifically for a specific Linux VoIP platform, namely the Linknat VOS2009 / 3000 softswitches (software switches).
Softswitch is a software that works as a VoIP server that manages traffic (audio / video / text) on a network telecommunications. It is a central element that ensures the connection between internal and external lines.
The purpose of CDRThief is to compromise VOS2009 / 3000 software and steal call metadata from internal MySQL databases. Metadata are, for example, callers' IP addresses, telephone numbers, start time and duration of calls, route and type.
Analyzing the malware, ESET investigators found that it tried to cover up the malicious Functionality using the encrypted Corrected Block TEA (XXTEA) and then run Base64 encoding on suspicious links.
Although access to the MySQL database is password protected and the key is encrypted in the file configuration, CDRThief can read it and decrypt it, showing that anyone who has developed it knows the platform very well.
From the malware functions, the researchers found that CDRThief is interested in boards containing system event logs, information on VoIP gateways and call metadata.
The malware delivers the information to a command and control (C2) server using JSON via HTTP after compressing and encrypting it with an RSA-1024 public key with a password.
The analysis revealed that CDRThief can be started from anywhere on the disk, using any file name.
It is not clear how persistence is achieved, but researchers say that the above command indicates that malware can be introduced into the platform's startup chain, and is rather disguised as a "Linknat softswitch component".
Based on current analysis observations, CDRThief could be used for cyber espionage or VoIP scams.