ClamAV

installation

sudo apt install clamav
sudo apt install clamtk # install GUI 

update

sudo freshclam

If update is not possible:

# -> Your ClamAV installation is OUTDATED!
wheris freshclam
wheris clamscan
ldd $(which freshclam)

and check for (old) libclamav.so

usage

clamscan -r -i /dir/to/scan/recursively

or start ClamTk-GUI.

chkrootkit

sudo apt install chkrootkit
chkrootkit -l
sudo chkrootkit