[QUIETEXIT](https://attack.mitre.org/software/S1084) is a novel backdoor, based on the open-source Dropbear SSH client-server software, that has been used by [APT29](https://attack.mitre.org/groups/G0016) since at least 2021. [APT29](https://attack.mitre.org/groups/G0016) has deployed [QUIETEXIT](https://attack.mitre.org/software/S1084) on opaque network appliances that typically don't support antivirus or endpoint detection and response tools within a victim environment.(Citation: Mandiant APT29 Eye Spy Email Nov 22)