When Sophos Anti-Virus for Linux is installed on an Ubuntu LiveCD installation, on-access scanning may not start automatically.
Also, files on the overlay filesystem (used by Ubuntu LiveCD) are not scanned.
First seen in
SAV for Linux 7.x
SAV for Linux 9.x
Ubuntu LiveCD and the overlay filesystem are not currently supported by Sophos Anti-Virus.
On-Access scanning is only supported on Operating Systems that have been installed to a hard disk drive.