VERY IMPORTANT

BlueShell is an open-source remote access trojan developed in Go language, primarily used by Chinese-based threat actors. A variant of BlueShell has been identified in post-intrusion activities by APT groups including BlackTech, targeting organizations in Japan, South Korea, and Thailand. This variant differs from the original through a dedicated dropper mechanism, proxy server-based C2 communication, and anti-forensic capabilities. The dropper deploys the variant to /tmp/kthread, disguises it as a Linux kernel worker process, and removes filesystem traces. Recent variants observed since 2024 include XOR-encoded configuration data and proxy functionality, indicating continuous development. The malware performs hostname verification, validates C2 certificates, and implements commands for file transfer, remote shell, and SOCKS5 proxy capabilities.