Virus:Additional Signatures

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Anti Virus - Additional Signatures

Introduction

SME Server uses Clam AntiVirus (http://www.clamav.net) as the default and built-in anti virus engine.

By default this system will automatically get virus signature updates from the clamav database. Other people and organizations have developed additional signatures which can be used with ClamAV. These include

In order to use these additional databases with your ClamAV installation you need to download them and add them to ClamAV. There is a script package from Sane Security which can be used to download and install the databases, and their addition provide 1,000's of new signatures for ClamAV to work with.

Installation

Log in to a console shell as root

Create and edit a new file. Add the following

#!/bin/sh
# script to install Bill Landry's <bill at inetmsg dot com> scripts
# for maintaining Sanesecurity signatures for clamav
# Copyright (C) 2009 Eric Shubert <ejs@shubes.net>
########################################################################
#  4/30/10 Amendments to install on SME Server - commented with SME
#  9/25/09 Totally refactored by Eric Shubert <ejs@shubes.net>
#  3/22/09 Originally Written by Jake Vickers <jake@qmailtoaster.com>
#
WEB_LOC=http://www.inetmsg.com/pub
PKG_NAME=clamav-unofficial-sigs
PKG_TGZ=$PKG_NAME.tar.gz
# SME = changed variable name throughout and directory name
SANE_DIR=/opt/sanesecurity

########################################################################
# initialization processing
#
a1_initialization(){

# Make sure we're root
if [ "$UID" != "0" ]; then
  echo "Error: You are not logged in as root, please su -"
  exit 1
fi 

# remove files from previous version
# SME - changed cron job from .sh to .cron, added removal of .sh script and redundant dbs
rm -rf       /etc/unofficial-clamav-sigs.conf \
 /etc/cron.hourly/unofficial-clamav-sigs.cron \
 /usr/unofficial-dbs \
 /usr/bin/unofficial-clamav-sigs.sh \
 /var/clamav/*.ndb \
 /var/clamav/*.ldb \
 /var/clamav/*.ftm \
 /var/clamav/*.hdb 

# set a temp directory for the tar file. $$ is the current shell ID.
TEMP_DIR=$(tempfile 2>/dev/null) || TEMP_DIR=/tmp/$me.$$ 

# make sure the temp directory is deleted when we're done
trap "rm -rf $TEMP_DIR" 0 1 2 5 15
}

###################################################################
## download and unpack current package
#
a3_download_unpack(){

rm -rf $TEMP_DIR
mkdir -p $TEMP_DIR
echo "$me $myver - getting latest version of $PKG_NAME ..."

wget -O $TEMP_DIR/$PKG_TGZ $WEB_LOC/$PKG_TGZ

if [ "$?" != "0" ]; then
  echo "$me - unable to reach $WEB_LOC/$PKG_TGZ, please try again later."
  exit 1
fi

tar -xz -C $TEMP_DIR -f $TEMP_DIR/$PKG_TGZ
}

###################################################################
## install the package files
#
a5_install_files(){

# SME - Added make directories
mkdir -p $SANE_DIR/bin
mkdir -p $SANE_DIR/etc
mkdir -p $SANE_DIR/man

# install the shell script
cp $TEMP_DIR/$PKG_NAME-*/$PKG_NAME.sh $SANE_DIR/bin/$PKG_NAME.sh
chmod 755 $SANE_DIR/bin/$PKG_NAME.sh
ln -sf ../..$SANE_DIR/bin/$PKG_NAME.sh /usr/sbin/$PKG_NAME.sh

# install the configuration file
# SME - removed substitutions for clamd reload - reload_opt and reload_dbs
# SME - removed substitution to change default dbs download directory
# SME - added substitution to set clamd_socket location
# SME - removed substitution to silence information output - but see cron job below

cat $TEMP_DIR/$PKG_NAME-*/$PKG_NAME.conf | sed \
    -e "s|/var/lib/clamav|/var/clamav|" \
    -e "/#clamd_socket=/aclamd_socket=\"/var/clamav/clamd.socket\"" \
    -e "s|enable_logging=\"no\"|enable_logging=\"yes\"|" \
    -e "s|log_file_path=\"/var/log\"|log_file_path=\"/var/log/clamav\"|" \
    -e "s|log_file_name=\"clamav-unofficial|log_file_name=\"unofficial|" \
    -e "s|configuration_complete=\"no\"|configuration_complete=\"yes\"|" \
    > $SANE_DIR/etc/$PKG_NAME.conf
ln -sf ../..$SANE_DIR/etc/$PKG_NAME.conf /etc/$PKG_NAME.conf

# install the man page
gzip $TEMP_DIR/$PKG_NAME-*/$PKG_NAME.8
cp $TEMP_DIR/$PKG_NAME-*/$PKG_NAME.8.gz $SANE_DIR/man/$PKG_NAME.8.gz
ln -sf ../../../..$SANE_DIR/man/$PKG_NAME.8.gz /usr/share/man/man8/$PKG_NAME.8.gz

# install the cron job (cannot symlink cron jobs)
grep "^#" $TEMP_DIR/$PKG_NAME-*/$PKG_NAME-cron \
    > /etc/cron.d/$PKG_NAME-cron
# SME - added redirect stdout to null device and stderr to stdout so we only get error output from cron job
echo -e "\n25 * * * * root /usr/sbin/$PKG_NAME.sh >/dev/null 2>&1" \
    >>/etc/cron.d/$PKG_NAME-cron

# install the logrotate spec
cat $TEMP_DIR/$PKG_NAME-*/$PKG_NAME-logrotate | sed \
    -e "s|clamav-unofficial|clamav/unofficial|" \
    > $SANE_DIR/etc/$PKG_NAME-logrotate
ln -sf ../..$SANE_DIR/etc/$PKG_NAME-logrotate /etc/logrotate.d/$PKG_NAME-logrotate

# install documentation files
# SME - removed superfluous $PKG_NAME sub-directory below $SANE_DIR/doc
mkdir -p $SANE_DIR/doc
mv $TEMP_DIR/$PKG_NAME-*/CHANGELOG $SANE_DIR/doc/CHANGELOG
mv $TEMP_DIR/$PKG_NAME-*/INSTALL   $SANE_DIR/doc/INSTALL
mv $TEMP_DIR/$PKG_NAME-*/LICENSE   $SANE_DIR/doc/LICENSE
mv $TEMP_DIR/$PKG_NAME-*/README    $SANE_DIR/doc/README
}

###################################################################
## main script execution begins here
#
me=${0##*/}
myver=v0.3.1-1 

a1_initialization

a3_download_unpack

a5_install_files

echo "$PKG_NAME installed successfully"
echo "clamav database files provided by Sanesecurity will be updated within an hour,"
echo " and continuously after that."
exit 0

Save the file as sanesecurity-install.sh

chmod 755 sanesecurity-install.sh

Now run the script. This will download the Sane Security package and install it for SME Server

./sanesecurity-install.sh

Run the Sane Security script for the first time to download the databases and check it works

/usr/sbin/clamav-unofficial-sigs.sh

If you want to immediately reload ClamAV to include the additional databases

signal-event clamav-update

Operation

Having installed the Sane Security package as above, it will operate as follows.

  • A cron job will run every hour and instigate the clamav-unofficial-sigs.sh script
  • The script will download the additional databases and add them to the /var/clamav directory
  • ClamAV will reload all its databases from /var/clamav every 30 minutes by default

Signature Databases

The additional databases to be downloaded and installed by the clamav-unofficial-sigs.sh script are controlled by the configuration file /etc/clamav-unofficial-sigs.conf

A default set of databases are defined for download. There are additional databases that can also be added to the list, or some or all of the defaults can be excluded. The configuration file is commented in this regard and gives an indication of the risk of false positives from the non-default databases.

To amend the databases you require, edit /etc/clamav-unofficial-sigs.conf and add or remove the database names as instructed.

  Note:
If removing databases from the download lists, don't forget to also delete them from /var/clamav and /usr/unofficial_dbs if they have been downloaded previously and exist


  Note:
Adding unofficial signatures increases memory usage. To increase the clamd memory limit try setting MemLimit to a value greater than 300000000 (see here for reference). Since clamav-0.96 and smeserver-clamav-2.0.0-8 the default MemLimit for clamd has been 600000000 and should be sufficient.


Old Installation Notes

A previous installation of the Sane Security scripts was provided for SME by swerts-knudsen.dk, and the installation notes for this are reproduced below for completeness. This is for version 2.4 of the scripts however, whereas the current version installed as above is 3.7 (April 2010)

Installation

cd /etc
wget http://sme.swerts-knudsen.dk/downloads/unofficial-clamav-sigs-2.4/unofficial-clamav-sigs.conf
cd /etc/cron.hourly
wget http://sme.swerts-knudsen.dk/downloads/unofficial-clamav-sigs-2.4/unofficial-clamav-sigs.cron
chmod +x unofficial-clamav-sigs.cron
cd /usr/bin
wget http://sme.swerts-knudsen.dk/downloads/unofficial-clamav-sigs-2.4/unofficial-clamav-sigs.sh
chmod +x unofficial-clamav-sigs.sh

When you run it manually the first time it will complain about missing GPG keys - Just run it again.

./unofficial-clamav-sigs.sh

ClamAV will by default reload its databases every 1800 secs (30mins) but you can force a reload with:

signal-event email-update

References

See original forum post http://forums.contribs.org/index.php?topic=37861.0

See also http://forums.contribs.org/index.php/topic,45872.0.html

Installation script originally produced by QmailToaster Plus - see http://qtp.qmailtoaster.com