Для начала проверьте LogFile в папке /var/packages/AntiVirus/target/engine/clamav/var
PS Из возможных корректирующих мероприятий:
1. Замена DNS провайдера на Google DNS,
2. "Поиграть" с зеркалами в файлике /var/packages/Antivirus/target/engine/clamav/etc/freshclam.conf
Database Mirror db.local.clamav.net
Database Mirror database.clamav.net
Database Mirror clamav.mirror.transip.nl
Лог пишет следующие
Sat Mar 19 11:30:39 2016 -> --------------------------------------
Sat Mar 19 11:30:39 2016 -> ClamAV update process started at Sat Mar 19 11:30:39 2016
Sat Mar 19 11:30:39 2016 -> WARNING: Your ClamAV installation is OUTDATED!
Sat Mar 19 11:30:39 2016 -> WARNING: Local version: 0.98.7 Recommended version: 0.99.1
Sat Mar 19 11:30:39 2016 -> DON'T PANIC! Read http://www.clamav.net/support/faq
Sat Mar 19 11:30:48 2016 -> ERROR: getfile: Unknown response from remote server (IP: 145.58.29.83)
Sat Mar 19 11:30:52 2016 -> ERROR: getpatch: Can't download main-56.cdiff from db.local.clamav.net
Sat Mar 19 11:30:52 2016 -> WARNING: Incremental update failed, trying to download main.cvd
Sat Mar 19 11:30:53 2016 -> ERROR: getfile: Unknown response from remote server (IP: 145.58.29.83)
Sat Mar 19 11:30:53 2016 -> ERROR: Can't download main.cvd from db.local.clamav.net
Sat Mar 19 11:30:53 2016 -> Giving up on db.local.clamav.net...
Sat Mar 19 11:30:53 2016 -> ClamAV update process started at Sat Mar 19 11:30:53 2016
Sat Mar 19 11:30:53 2016 -> WARNING: Your ClamAV installation is OUTDATED!
Sat Mar 19 11:30:53 2016 -> WARNING: Local version: 0.98.7 Recommended version: 0.99.1
Sat Mar 19 11:30:53 2016 -> DON'T PANIC! Read http://www.clamav.net/support/faq
Sat Mar 19 11:31:19 2016 -> nonblock_recv: recv timing out (12 secs)
Sat Mar 19 11:31:19 2016 -> ERROR: getfile: Error while reading database from database.clamav.net (IP: 217.19.16.188): Operation now in progress
Sat Mar 19 11:31:19 2016 -> ERROR: getpatch: Can't download main-56.cdiff from database.clamav.net
Sat Mar 19 11:31:19 2016 -> WARNING: Incremental update failed, trying to download main.cvd
Sat Mar 19 11:32:59 2016 -> --------------------------------------
Sat Mar 19 11:32:59 2016 -> ClamAV update process started at Sat Mar 19 11:32:59 2016
Sat Mar 19 11:32:59 2016 -> WARNING: Your ClamAV installation is OUTDATED!
Sat Mar 19 11:32:59 2016 -> WARNING: Local version: 0.98.7 Recommended version: 0.99.1
Sat Mar 19 11:32:59 2016 -> DON'T PANIC! Read http://www.clamav.net/support/faq
Sat Mar 19 11:33:06 2016 -> Trying host db.local.clamav.net (194.109.6.97)...
Sat Mar 19 11:33:10 2016 -> Empty script main-56.cdiff, need to download entire database
Sat Mar 19 11:35:18 2016 -> Downloading main.cvd [100%]
И как это обновить.