12.11_find_sgid_files.sh

#!/bin/bash

#
# harbian-audit for Debian GNU/Linux 7/8/9 or CentOS 8 Hardening
#

#
# 12.11 Find SGID System Executables (Not Scored)
#

#set -e # One error, it's over, for some user to audit desktop evn 

# One variable unset, it's over
set -u

HARDENING_LEVEL=2

# This function will be called if the script status is on enabled / audit mode
audit () {
    info "Checking if there are sgid files"
    RESULT=$(df --local -P | awk {'if (NR!=1) print $6'} | xargs -I '{}' $SUDO_CMD find '{}' -xdev -type f -perm -2000 -print)
    for BINARY in $RESULT; do
        if grep -q $BINARY <<< "$EXCEPTIONS"; then
            debug "$BINARY is confirmed as an exception"
            RESULT=$(sed "s!$BINARY!!" <<< $RESULT)
        fi
    done
    if [ ! -z "$RESULT" ]; then
        crit "Some sgid files are present"
        FORMATTED_RESULT=$(sed "s/ /\n/g" <<< $RESULT | sort | uniq | tr '\n' ' ')
        crit "$FORMATTED_RESULT"
		FNRET=1
    else
        ok "No unknown sgid files found"
		FNRET=0
    fi
}

# This function will be called if the script status is on enabled mode
apply () {
	if [ $FNRET = 1 ]; then
    	warn "Removing sgid on valid binary may seriously harm your system, report only here"
	else
        ok "No unknown sgid files found"
	fi
}

# This function will create the config file for this check with default values
create_config() {
    cat <<EOF
status=disabled
# Put here valid binaries with sgid enabled separated by spaces
EXCEPTIONS="/sbin/unix_chkpwd /usr/bin/bsd-write /usr/bin/chage /usr/bin/crontab /usr/bin/expiry /usr/bin/mutt_dotlock /usr/bin/screen /usr/bin/ssh-agent /usr/bin/wall /usr/sbin/postdrop /usr/sbin/postqueue /usr/bin/at /usr/bin/dotlockfile /usr/bin/mail-lock /usr/bin/mail-touchlock /usr/bin/mail-unlock"
EOF
}

# This function will check config parameters required
check_config() {
    if [ -z "$EXCEPTIONS" ]; then
        EXCEPTIONS="@"
    fi
}

# Source Root Dir Parameter
if [ -r /etc/default/cis-hardening ]; then
    . /etc/default/cis-hardening
fi
if [ -z "$CIS_ROOT_DIR" ]; then
     echo "There is no /etc/default/cis-hardening file nor cis-hardening directory in current environment."
     echo "Cannot source CIS_ROOT_DIR variable, aborting."
    exit 128
fi

# Main function, will call the proper functions given the configuration (audit, enabled, disabled)
if [ -r $CIS_ROOT_DIR/lib/main.sh ]; then
    . $CIS_ROOT_DIR/lib/main.sh
else
    echo "Cannot find main.sh, have you correctly defined your root directory? Current value is $CIS_ROOT_DIR in /etc/default/cis-hardening"
    exit 128
fi