Custom malware on network devices
https://www.bleepingcomputer.com/news/security/us-and-japan-warn-of-chinese-hackers-backdooring-cisco-routers/
US and Japanese law enforcement and cybersecurity agencies warn of the Chinese 'BlackTech' hackers breaching network devices to install custom backdoors for access to corporate networks.
The joint report comes from the FBI, NSA, CISA, and the Japanese NISC (cybersecurity) and NPA (police), who explain that the state-sponsored hacking group is breaching network devices at international subsidiaries to pivot to the networks of corporate headquarters.