debian-cis/bin/hardening/1.1.21_sticky_bit_world_writable_folder.sh

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#!/bin/bash
# run-shellcheck
#
# CIS Debian Hardening
#
#
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# 1.1.21 Ensure sticky bit is set on all world-writable directories (Scored)
#
set -e # One error, it's over
set -u # One variable unset, it's over
# shellcheck disable=2034
HARDENING_LEVEL=2
# shellcheck disable=2034
DESCRIPTION="Set sticky bit on world writable directories to prevent users from deleting or renaming files that are not owned by them."
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EXCEPTIONS=''
# find emits following error if directory or file disappear during
# tree traversal: find: /tmp/xxx: No such file or directory
FIND_IGNORE_NOSUCHFILE_ERR=false
# This function will be called if the script status is on enabled / audit mode
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audit() {
info "Checking if setuid is set on world writable Directories"
if [ -n "$EXCEPTIONS" ]; then
# maybe EXCEPTIONS allow us to filter out some FS
FS_NAMES=$(df --local -P | awk '{if (NR!=1) print $6}' | grep -vE "$EXCEPTIONS")
[ "${FIND_IGNORE_NOSUCHFILE_ERR}" = true ] && set +e
# shellcheck disable=SC2086
RESULT=$($SUDO_CMD find $FS_NAMES -xdev -ignore_readdir_race -type d \( -perm -0002 -a ! -perm -1000 \) -regextype 'egrep' ! -regex $EXCEPTIONS -print 2>/dev/null)
[ "${FIND_IGNORE_NOSUCHFILE_ERR}" = true ] && set -e
else
FS_NAMES=$(df --local -P | awk '{if (NR!=1) print $6}')
[ "${FIND_IGNORE_NOSUCHFILE_ERR}" = true ] && set +e
# shellcheck disable=SC2086
RESULT=$($SUDO_CMD find $FS_NAMES -xdev -ignore_readdir_race -type d \( -perm -0002 -a ! -perm -1000 \) -print 2>/dev/null)
[ "${FIND_IGNORE_NOSUCHFILE_ERR}" = true ] && set -e
fi
if [ -n "$RESULT" ]; then
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crit "Some world writable directories are not on sticky bit mode!"
# shellcheck disable=SC2001
FORMATTED_RESULT=$(sed "s/ /\n/g" <<<"$RESULT" | sort | uniq | tr '\n' ' ')
crit "$FORMATTED_RESULT"
else
ok "All world writable directories have a sticky bit"
fi
}
# This function will be called if the script status is on enabled mode
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apply() {
if [ -n "$EXCEPTIONS" ]; then
# shellcheck disable=SC2086
RESULT=$(df --local -P | awk '{if (NR!=1) print $6}' | grep -vE "$EXCEPTIONS" | xargs -I '{}' find '{}' -xdev -ignore_readdir_race -type d \( -perm -0002 -a ! -perm -1000 \) -regextype 'egrep' ! -regex "$EXCEPTIONS" -print 2>/dev/null)
else
RESULT=$(df --local -P | awk '{if (NR!=1) print $6}' | xargs -I '{}' find '{}' -xdev -ignore_readdir_race -type d \( -perm -0002 -a ! -perm -1000 \) -print 2>/dev/null)
fi
if [ -n "$RESULT" ]; then
warn "Setting sticky bit on world writable directories"
df --local -P | awk '{if (NR!=1) print $6}' | xargs -I '{}' find '{}' -xdev -ignore_readdir_race -type d -perm -0002 2>/dev/null | xargs chmod a+t
else
ok "All world writable directories have a sticky bit, nothing to apply"
fi
}
# This function will check config parameters required
check_config() {
# No param for this function
:
}
# Source Root Dir Parameter
if [ -r /etc/default/cis-hardening ]; then
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# shellcheck source=../../debian/default
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. /etc/default/cis-hardening
fi
if [ -z "$CIS_LIB_DIR" ]; then
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echo "There is no /etc/default/cis-hardening file nor cis-hardening directory in current environment."
echo "Cannot source CIS_LIB_DIR variable, aborting."
exit 128
fi
# Main function, will call the proper functions given the configuration (audit, enabled, disabled)
if [ -r "${CIS_LIB_DIR}"/main.sh ]; then
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# shellcheck source=../../lib/main.sh
. "${CIS_LIB_DIR}"/main.sh
else
echo "Cannot find main.sh, have you correctly defined your root directory? Current value is $CIS_LIB_DIR in /etc/default/cis-hardening"
exit 128
fi