Description

A cyber-espionage campaign attributed to a China-linked threat group identified as UAT-9244 has been actively targeting telecommunications providers across South America since 2024. The operation involves a sophisticated multi-stage malware toolkit designed to compromise both Windows and Linux systems within telecom infrastructure. Security researchers describe the activity as a stealthy and persistent campaign intended to maintain long-term access to sensitive network environments and critical infrastructure systems. The attackers rely on a three-stage malware framework that focuses on different layers of telecom networks. One of the primary components, TernDoor, is a Windows-based backdoor derived from the earlier CrowDoor malware family. The malware abuses DLL sideloading to bypass security defenses by launching a legitimate executable (`wsprint.exe`) that loads a malicious DLL in the background. Once active, the backdoor decrypts its payload and allows attackers to run remote commands, manipulate files, and gather system information from compromised machines. It also deploys an encrypted driver named `WSPrint.sys`, which can disable or terminate security processes, helping the attackers remain undetected. For Linux and embedded telecom systems, the threat actors use another malware variant called PeerTime, an ELF-based backdoor compatible with multiple architectures such as ARM and MIPS. Unlike traditional command-and-control methods, PeerTime leverages the BitTorrent peer-to-peer protocol to communicate with other infected systems and distribute payloads, making the infrastructure more resilient. Additionally, the attackers deploy BruteEntry, a Go-based brute-force tool installed on compromised edge devices. These infected devices act as relay nodes that receive target lists and automatically attempt credential-guessing attacks against services like SSH, Postgres, and Apache Tomcat servers, enabling the attackers to expand their foothold within telecom networks.