Two security experts demonstrated how internal LTE/3G modems can be hacked to help malware survive OS reinstalls. Malware that infect a machine could rewrite the firmware of a popular Huawei LTE modem to maintain the infection even if the host OS is reinstalled. The experts also explained that the malicious firmware could be also instructed to ignore any subsequent subsequent firmware update, in this case, the unique way to restore the infected PC is to remove the infected modem module. Huawei has fixed the issue, introducing a secure boot that blocks the flashing of unauthorized firmware images.”]
Source: https://securityaffairs.co/wordpress/39252/hacking/internal-modem-hacking.html