xref: /src/etc/security

#!/bin/sh -
#
#	$NetBSD: security,v 1.18 1997/04/17 07:42:07 mikel Exp $
#	from: @(#)security	8.1 (Berkeley) 6/9/93
#

PATH=/sbin:/usr/sbin:/bin:/usr/bin

umask 077

if [ -s /etc/security.conf ]; then
	. /etc/security.conf
fi

SECUREDIR=/tmp/_securedir.$$
if ! mkdir $SECUREDIR; then
	echo can not create $SECUREDIR.
	exit 1
fi

if ! cd $SECUREDIR; then
	echo can not chdir to $SECUREDIR.
	exit 1
fi

ERR=secure1.$$
TMP1=secure2.$$
TMP2=secure3.$$
TMP3=secure4.$$
LIST=secure5.$$
OUTPUT=secure6.$$

trap 'rm -rf $SECUREDIR' 0

MP=/etc/master.passwd

# this is used several times.
awk -F: '{ print $1 " " $3 }' $MP | sort -n +1 > $TMP1

# Check the master password file syntax.
if [ "$check_passwd" = YES ]; then
	awk -F: '{
		if ($0 ~ /^[	 ]*$/) {
			printf("Line %d is a blank line.\n", NR);
			next;
		}
		if (NF != 10)
			printf("Line %d has the wrong number of fields.\n", NR);
		if ($1 !~ /^[A-Za-z0-9]*$/)
			printf("Login %s has non-alphanumeric characters.\n", $1);
		if (length($1) > 8)
			printf("Login %s has more than 8 characters.\n", $1);
		if ($2 == "")
			printf("Login %s has no password.\n", $1);
		if (length($2) != 13 && $2 != "" && ($10 ~ /.*sh$/ || $10 == ""))
			printf("Login %s is off but still has a valid shell.\n", $1);
		if ($3 == 0 && $1 != "root" && $1 != "toor")
			printf("Login %s has a user id of 0.\n", $1);
		if ($3 < 0)
			printf("Login %s has a negative user id.\n", $1);
		if ($4 < 0)
			printf("Login %s has a negative group id.\n", $1);
	}' < $MP > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking the $MP file:\n"
		cat $OUTPUT
	fi

	awk -F: '{ print $1 }' $MP | sort | uniq -d > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\n$MP has duplicate user names.\n"
		column $OUTPUT
	fi

	< $TMP1 uniq -d -f 1 | awk '{ print $2 }' > $TMP2
	if [ -s $TMP2 ] ; then
		printf "\n$MP has duplicate user id's.\n"
		while read uid; do
			grep -w $uid $TMP1
		done < $TMP2 | column
	fi
fi

# Backup the master password file; a special case, the normal backup
# mechanisms also print out file differences and we don't want to do
# that because this file has encrypted passwords in it.
CUR=/var/backups/`basename $MP`.current
BACK=/var/backups/`basename $MP`.backup
if [ -s $CUR ] ; then
	if cmp -s $CUR $MP; then
		:
	else
		cp -p $CUR $BACK
		cp -p $MP $CUR
		chown root.wheel $CUR
	fi
else
	cp -p $MP $CUR
	chown root.wheel $CUR
fi

# Check the group file syntax.
if [ "$check_group" = YES ]; then
	GRP=/etc/group
	awk -F: '{
		if ($0 ~ /^[	 ]*$/) {
			printf("Line %d is a blank line.\n", NR);
			next;
		}
		if (NF != 4)
			printf("Line %d has the wrong number of fields.\n", NR);
		if ($1 !~ /^[A-za-z0-9]*$/)
			printf("Group %s has non-alphanumeric characters.\n", $1);
		if (length($1) > 8)
			printf("Group %s has more than 8 characters.\n", $1);
		if ($3 !~ /[0-9]*/)
			printf("Login %s has a negative group id.\n", $1);
	}' < $GRP > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking the $GRP file:\n"
		cat $OUTPUT
	fi

	awk -F: '{ print $1 }' $GRP | sort | uniq -d > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\n$GRP has duplicate group names.\n"
		column $OUTPUT
	fi
fi

# Check for root paths, umask values in startup files.
# The check for the root paths is problematical -- it's likely to fail
# in other environments.  Once the shells have been modified to warn
# of '.' in the path, the path tests should go away.
if [ "$check_rootdotfiles" = YES ]; then
	cp /dev/null $OUTPUT
	rhome=`csh -fc "echo ~root"`
	umaskset=no
	list="/etc/csh.cshrc /etc/csh.login ${rhome}/.cshrc ${rhome}/.login"
	for i in $list ; do
		if [ -f $i ] ; then
			if egrep umask $i > /dev/null ; then
				umaskset=yes
			fi
			egrep umask $i |
			awk '$2 % 100 < 20 \
				{ print "Root umask is group writeable" }
			     $2 % 10 < 2 \
				{ print "Root umask is other writeable" }' >> $OUTPUT
			/bin/csh -f -s << end-of-csh > /dev/null 2>&1
				unset path
				source $i
				/bin/ls -ldgT \$path > $TMP1
end-of-csh
			awk '{
				if ($10 ~ /^\.$/) {
					print "The root path includes .";
					next;
				}
			     }
			     $1 ~ /^d....w/ \
		{ print "Root path directory " $10 " is group writeable." } \
			     $1 ~ /^d.......w/ \
		{ print "Root path directory " $10 " is other writeable." }' \
			< $TMP1 >> $OUTPUT
		fi
	done
	if [ $umaskset = "no" -o -s $OUTPUT ] ; then
		printf "\nChecking root csh paths, umask values:\n$list\n"
		if [ -s $OUTPUT ]; then
			cat $OUTPUT
		fi
		if [ $umaskset = "no" ] ; then
			printf "\nRoot csh startup files do not set the umask.\n"
		fi
	fi

	cp /dev/null $OUTPUT
	rhome=/root
	umaskset=no
	list="${rhome}/.profile"
	for i in $list; do
		if [ -f $i ] ; then
			if egrep umask $i > /dev/null ; then
				umaskset=yes
			fi
			egrep umask $i |
			awk '$2 % 100 < 20 \
				{ print "Root umask is group writeable" } \
			     $2 % 10 < 2 \
				{ print "Root umask is other writeable" }' >> $OUTPUT
			/bin/sh << end-of-sh > /dev/null 2>&1
				PATH=
				. $i
				list=\`echo \$PATH | /usr/bin/sed -e 's/:/ /g'\`
				/bin/ls -ldgT \$list > $TMP1
end-of-sh
			awk '{
				if ($10 ~ /^\.$/) {
					print "The root path includes .";
					next;
				}
			     }
			     $1 ~ /^d....w/ \
		{ print "Root path directory " $10 " is group writeable." } \
			     $1 ~ /^d.......w/ \
		{ print "Root path directory " $10 " is other writeable." }' \
			< $TMP1 >> $OUTPUT

		fi
	done
	if [ $umaskset = "no" -o -s $OUTPUT ] ; then
		printf "\nChecking root sh paths, umask values:\n$list\n"
		if [ -s $OUTPUT ]; then
			cat $OUTPUT
		fi
		if [ $umaskset = "no" ] ; then
			printf "\nRoot sh startup files do not set the umask.\n"
		fi
	fi
fi

# Root and uucp should both be in /etc/ftpusers.
if [ "$check_ftpusers" = YES ]; then
	if egrep root /etc/ftpusers > /dev/null ; then
		:
	else
		printf "\nRoot not listed in /etc/ftpusers file.\n"
	fi
	if egrep uucp /etc/ftpusers > /dev/null ; then
		:
	else
		printf "\nUucp not listed in /etc/ftpusers file.\n"
	fi
fi

# Uudecode should not be in the /etc/aliases file.
if [ "$check_aliases" = YES ]; then
	if egrep '^[^#]*(uudecode|decode).*\|' /etc/aliases; then
		printf "\nEntry for uudecode in /etc/aliases file.\n"
	fi
fi

# Files that should not have + signs.
if [ "$check_rhosts" = YES ]; then
	list="/etc/hosts.equiv /etc/hosts.lpd"
	for f in $list ; do
		if [ -f $f ] && egrep '\+' $f > /dev/null ; then
			printf "\nPlus sign in $f file.\n"
		fi
	done

	# Check for special users with .rhosts files.  Only root and toor should
	# have .rhosts files.  Also, .rhosts files should not have plus signs.
	awk -F: '$1 != "root" && $1 != "toor" && \
		($3 < 100 || $1 == "ftp" || $1 == "uucp") \
			{ print $1 " " $9 }' /etc/master.passwd |
	while read uid homedir; do
		if [ -f ${homedir}/.rhosts ] ; then
			rhost=`ls -ldgT ${homedir}/.rhosts`
			printf "$uid: $rhost\n"
		fi
	done > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking for special users with .rhosts files.\n"
		cat $OUTPUT
	fi

	awk -F: '{ print $1 " " $9 }' /etc/master.passwd | \
	while read uid homedir; do
		if [ -f ${homedir}/.rhosts ] && \
		    egrep '\+' ${homedir}/.rhosts > /dev/null ; then
			printf "$uid: + in .rhosts file.\n"
		fi
	done > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking .rhosts files syntax.\n"
		cat $OUTPUT
	fi
fi

# Check home directories.  Directories should not be owned by someone else
# or writeable.
if [ "$check_homes" = YES ]; then
	awk -F: '{ print $1 " " $9 }' /etc/master.passwd | \
	while read uid homedir; do
		if [ -d ${homedir}/ ] ; then
			file=`ls -ldgT ${homedir}`
			printf "$uid $file\n"
		fi
	done |
	awk '$1 != $4 && $4 != "root" \
		{ print "user " $1 " home directory is owned by " $4 }
	     $2 ~ /^-....w/ \
		{ print "user " $1 " home directory is group writeable" }
	     $2 ~ /^-.......w/ \
		{ print "user " $1 " home directory is other writeable" }' > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking home directories.\n"
		cat $OUTPUT
	fi

	# Files that should not be owned by someone else or readable.
	list=".netrc .rhosts"
	awk -F: '{ print $1 " " $9 }' /etc/master.passwd | \
	while read uid homedir; do
		for f in $list ; do
			file=${homedir}/${f}
			if [ -f $file ] ; then
				printf "$uid $f `ls -ldgT $file`\n"
			fi
		done
	done |
	awk '$1 != $5 && $5 != "root" \
		{ print "user " $1 " " $2 " file is owned by " $5 }
	     $3 ~ /^-...r/ \
		{ print "user " $1 " " $2 " file is group readable" }
	     $3 ~ /^-......r/ \
		{ print "user " $1 " " $2 " file is other readable" }
	     $3 ~ /^-....w/ \
		{ print "user " $1 " " $2 " file is group writeable" }
	     $3 ~ /^-.......w/ \
		{ print "user " $1 " " $2 " file is other writeable" }' > $OUTPUT

	# Files that should not be owned by someone else or writeable.
	list=".bashrc .cshrc .emacs .exrc .forward .klogin .login .logout \
	      .profile .tcshrc .qmail"
	awk -F: '{ print $1 " " $9 }' /etc/master.passwd | \
	while read uid homedir; do
		for f in $list ; do
			file=${homedir}/${f}
			if [ -f $file ] ; then
				printf "$uid $f `ls -ldgT $file`\n"
			fi
		done
	done |
	awk '$1 != $5 && $5 != "root" \
		{ print "user " $1 " " $2 " file is owned by " $5 }
	     $3 ~ /^-....w/ \
		{ print "user " $1 " " $2 " file is group writeable" }
	     $3 ~ /^-.......w/ \
		{ print "user " $1 " " $2 " file is other writeable" }' >> $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking dot files.\n"
		cat $OUTPUT
	fi
fi

# Mailboxes should be owned by user and unreadable.
if [ "$check_varmail" = YES ]; then
	ls -l /var/mail | sed 1d | \
	awk '$3 != $9 \
		{ print "user " $9 " mailbox is owned by " $3 }
	     $1 != "-rw-------" \
		{ print "user " $9 " mailbox is " $1 ", group " $4 }' > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking mailbox ownership.\n"
		cat $OUTPUT
	fi
fi

if [ "$check_nfs" = YES ]; then
	if [ -f /etc/exports ]; then
	    # File systems should not be globally exported.
	    awk '{
		readonly = 0;
		for (i = 2; i <= NF; ++i) {
			if ($i ~ /-ro/)
				readonly = 1;
			else if ($i !~ /^-/)
				next;
		}
		if (readonly)
			print "File system " $1 " globally exported, read-only."
		else
			print "File system " $1 " globally exported, read-write."
	    }' < /etc/exports > $OUTPUT
	    if [ -s $OUTPUT ] ; then
		printf "\nChecking for globally exported file systems.\n"
		cat $OUTPUT
	    fi
	fi
fi

# Display any changes in setuid files and devices.
if [ "$check_devices" = YES ]; then
	printf "\nChecking setuid files and devices:\n"
	(find / \( ! -fstype local -o -fstype fdesc -o -fstype kernfs \
			-o -fstype procfs \) -a -prune -o \
	    \( -perm -u+s -o \( -perm -g+s -a ! -type d \) -o \
	       ! -type d -a ! -type f -a ! -type l -a \
	       ! -type s \) -print | \
	sort | sed -e 's/^/ls -ldgT /' | sh > $LIST) 2> $OUTPUT

	# Display any errors that occurred during system file walk.
	if [ -s $OUTPUT ] ; then
		printf "Setuid/device find errors:\n"
		cat $OUTPUT
		printf "\n"
	fi

	# Display any changes in the setuid file list.
	egrep -v '^[bc]' $LIST > $TMP1
	if [ -s $TMP1 ] ; then
		# Check to make sure uudecode isn't setuid.
		if grep -w uudecode $TMP1 > /dev/null ; then
			printf "\nUudecode is setuid.\n"
		fi

		CUR=/var/backups/setuid.current
		BACK=/var/backups/setuid.backup

		if [ -s $CUR ] ; then
			if cmp -s $CUR $TMP1 ; then
				:
			else
				> $TMP2
				join -110 -210 -v2 $CUR $TMP1 > $OUTPUT
				if [ -s $OUTPUT ] ; then
					printf "Setuid additions:\n"
					tee -a $TMP2 < $OUTPUT
					printf "\n"
				fi

				join -110 -210 -v1 $CUR $TMP1 > $OUTPUT
				if [ -s $OUTPUT ] ; then
					printf "Setuid deletions:\n"
					tee -a $TMP2 < $OUTPUT
					printf "\n"
				fi

				sort +9 $TMP2 $CUR $TMP1 | \
				    sed -e 's/[	 ][	 ]*/ /g' | uniq -u > $OUTPUT
				if [ -s $OUTPUT ] ; then
					printf "Setuid changes:\n"
					column -t $OUTPUT
					printf "\n"
				fi

				cp $CUR $BACK
				cp $TMP1 $CUR
			fi
		else
			printf "Setuid additions:\n"
			column -t $TMP1
			printf "\n"
			cp $TMP1 $CUR
		fi
	fi

	# Check for block and character disk devices that are readable or writeable
	# or not owned by root.operator.
	>$TMP1
	DISKLIST="dk fd hd hk hp jb kra ra rb rd rl rx rz sd up wd xd xy"
	for i in $DISKLIST; do
		egrep "^b.*/${i}[0-9][0-9]*[a-p]$"  $LIST >> $TMP1
		egrep "^c.*/r${i}[0-9][0-9]*[a-p]$"  $LIST >> $TMP1
	done

	awk '$3 != "root" || $4 != "operator" || $1 !~ /.rw-r-----/ \
		{ printf("Disk %s is user %s, group %s, permissions %s.\n", \
		    $11, $3, $4, $1); }' < $TMP1 > $OUTPUT
	if [ -s $OUTPUT ] ; then
		printf "\nChecking disk ownership and permissions.\n"
		cat $OUTPUT
		printf "\n"
	fi

	# Display any changes in the device file list.
	egrep '^[bc]' $LIST | sort +10 > $TMP1
	if [ -s $TMP1 ] ; then
		CUR=/var/backups/device.current
		BACK=/var/backups/device.backup

		if [ -s $CUR ] ; then
			if cmp -s $CUR $TMP1 ; then
				:
			else
				> $TMP2
				join -111 -211 -v2 $CUR $TMP1 > $OUTPUT
				if [ -s $OUTPUT ] ; then
					printf "Device additions:\n"
					tee -a $TMP2 < $OUTPUT
					printf "\n"
				fi

				join -111 -211 -v1 $CUR $TMP1 > $OUTPUT
				if [ -s $OUTPUT ] ; then
					printf "Device deletions:\n"
					tee -a $TMP2 < $OUTPUT
					printf "\n"
				fi

				# Report any block device change.  Ignore character
				# devices, only the name is significant.
				cat $TMP2 $CUR $TMP1 | \
				sed -e '/^c/d' | \
				sort +10 | \
				sed -e 's/[	 ][	 ]*/ /g' | \
				uniq -u > $OUTPUT
				if [ -s $OUTPUT ] ; then
					printf "Block device changes:\n"
					column -t $OUTPUT
					printf "\n"
				fi

				cp $CUR $BACK
				cp $TMP1 $CUR
			fi
		else
			printf "Device additions:\n"
			column -t $TMP1
			printf "\n"
			cp $TMP1 $CUR
		fi
	fi
fi

# Check special files.
# Check system binaries.
#
# Create the mtree tree specifications using:
#
#	mtree -cx -pDIR -kcksum,gid,mode,nlink,size,link,time,uid > DIR.secure
#	chown root.wheel DIR.secure
#	chmod 600 DIR.secure
#
# Note, this is not complete protection against Trojan horsed binaries, as
# the hacker can modify the tree specification to match the replaced binary.
# For details on really protecting yourself against modified binaries, see
# the mtree(8) manual page.
if [ "$check_mtree" = YES ]; then
	mtree -e -p / -f /etc/mtree/special > $OUTPUT
	if [ -s $OUTPUT ]; then
		printf "\nChecking special files and directories.\n"
		cat $OUTPUT
	fi

	> $OUTPUT
	for file in /etc/mtree/*.secure; do
		[ $file = '/etc/mtree/*.secure' ] && continue
		tree=`sed -n -e '3s/.* //p' -e 3q $file`
		mtree -f $file -p $tree > $TMP1
		if [ -s $TMP1 ]; then
			printf "\nChecking $tree:\n" >> $OUTPUT
			cat $TMP1 >> $OUTPUT
		fi
	done
	if [ -s $OUTPUT ]; then
		printf "\nChecking system binaries:\n"
		cat $OUTPUT
	fi
fi

# List of files that get backed up and checked for any modifications.  Each
# file is expected to have two backups, /var/backups/file.{current,backup}.
# Any changes cause the files to rotate.
if [ "$check_changelist" = YES ] && [ -s /etc/changelist ] ; then
	for file in `cat /etc/changelist`; do
		CUR=/var/backups/`basename $file`.current
		BACK=/var/backups/`basename $file`.backup
		if [ -s $file ]; then
			if [ -s $CUR ] ; then
				diff $CUR $file > $OUTPUT
				if [ -s $OUTPUT ] ; then
		printf "\n======\n%s diffs (OLD < > NEW)\n======\n" $file
					cat $OUTPUT
					cp -p $CUR $BACK
					cp -p $file $CUR
					chown root.wheel $CUR $BACK
				fi
			else
				cp -p $file $CUR
				chown root.wheel $CUR
			fi
		fi
	done
fi