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names of set-uid files are no longer passed to a shell.
Thanks to deraadt for pointing out the -ls flag on find.

#!/bin/sh -
#
#	$OpenBSD: security,v 1.10 1996/09/20 20:35:37 bitblt Exp $
#
PATH=/sbin:/usr/sbin:/bin:/usr/bin

umask 077

DIR=/tmp/_secure$$
ERR=$DIR/_secure1
TMP1=$DIR/_secure2
TMP2=$DIR/_secure3
TMP3=$DIR/_secure4
LIST=$DIR/_secure5
OUTPUT=$DIR/_secure6


if ! mkdir $DIR ; then
	printf "tmp directory %s already exists, looks like:\n" $DIR
	ls -alF $DIR
	exit 1
fi

trap 'rm -rf $DIR' 0

# Check the master password file syntax.
MP=/etc/master.passwd
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 ($1 ~ /^[+-].*$/)
		next;
	if ($1 == "")
		printf("Line %d has an empty login field.\n",NR);
	else if ($1 !~ /^[A-Za-z0-9][A-Za-z0-9_-]*$/)
		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 && ($10 ~ /.*sh$/ || $10 == ""))
		printf("Login %s is off but still has a valid shell.\n", $1);
	if ($3 == 0 && $1 != "root")
		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

awk -F: '{ print $1 " " $3 }' $MP | sort -n +1 | tee $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

# 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.
if [ ! -d /var/backups ] ; then
	mkdir /var/backups
	chmod 755 /var/backups
fi
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.
GRP=/etc/group
awk -F: '{
	if ($0 ~ /^[	 ]*$/) {
		printf("Line %d is a blank line.\n", NR);
		next;
	}
	if ($1 ~ /^[+-].*$/)
		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

# 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.
> $OUTPUT
rhome=/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

> $OUTPUT
rhome=/root
umaskset=no
list="${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

# Root and uucp should both be in /etc/ftpusers.
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

# Uudecode should not be in the /etc/aliases file.
if egrep 'uudecode|decode' /etc/aliases; then
	printf "\nThere is an entry for uudecode in the /etc/aliases file.\n"
fi

# Files that should not have + signs.
list="/etc/hosts.equiv /etc/shosts.equiv /etc/hosts.lpd"
for f in $list ; do
	if [ -s $f ] ; then
		awk '{
			if ($0 ~ /^\+@.*$/ )
				next;
			if ($0 ~ /^\+.*$/ )
				printf("\nPlus sign in %s file.\n", FILENAME);
		}' $f
	fi
done

# Check for special users with .rhosts/.shosts files.  Only root should
# have .rhosts/.shosts files.  Also, .rhosts/.shosts files
# should not have plus signs.
awk -F: '$1 != "root" && $1 !~ /^[+-].*$/ && \
	($3 < 100 || $1 == "ftp" || $1 == "uucp") \
		{ print $1 " " $6 }' /etc/passwd |
while read uid homedir; do
	for j in .rhosts .shosts; do
		if [ -f ${homedir}/$j ] ; then
			rhost=`ls -ldgT ${homedir}/$j`
			printf "$uid: $rhost\n"
		fi
	done
done > $OUTPUT
if [ -s $OUTPUT ] ; then
	printf "\nChecking for special users with .rhosts/.shosts files.\n"
	cat $OUTPUT
fi

awk -F: '{ print $1 " " $6 }' /etc/passwd | \
while read uid homedir; do
	for j in .rhosts .shosts; do
		if [ -f ${homedir}/$j ] ; then
			awk '{
				if ($0 ~ /^+@.*$/ )
					next;
				if ($0 ~ /^\+[ 	]*$/ )
					printf("%s has + sign in it.\n",
					    FILENAME);
			}' ${homedir}/$j
		fi
	done
done > $OUTPUT
if [ -s $OUTPUT ] ; then
	printf "\nChecking .rhosts/.shosts files syntax.\n"
	cat $OUTPUT
fi

# Check home directories.  Directories should not be owned by someone else
# or writeable.
awk -F: '{ if ( $1 !~ /^[+-].*$/ ) print $1 " " $6 }' /etc/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 .shosts"
awk -F: '{ print $1 " " $6 }' /etc/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 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"
awk -F: '{ print $1 " " $6 }' /etc/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

# Mailboxes should be owned by user and unreadable.
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

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

# Display any changes in setuid/setgid files and devices.
pending="\nChecking setuid/setgid files and devices:\n"
(find / \( ! -fstype local -o -fstype fdesc -o -fstype kernfs \
		-o -fstype procfs \) -a -prune -o \
	-type f -a \( -perm -u+s -o -perm -g+s \) -print -o \
	! -type d -a ! -type f -a ! -type l -a ! -type s -ls | \
sort > $LIST) 2> $OUTPUT

# Display any errors that occurred during system file walk.
if [ -s $OUTPUT ] ; then
	printf "${pending}Setuid/device find errors:\n"
	pending=
	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 $TMP1 > /dev/null ; then
		printf "${pending}\nUudecode is setuid.\n"
		pending=
	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 $OUTPUT ] ; then
				printf "${pending}Setuid additions:\n"
				pending=
				tee -a $TMP2 < $OUTPUT
				printf "\n"
			fi

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

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

			cp $CUR $BACK
			cp $TMP1 $CUR
		fi
	else
		printf "${pending}Setuid additions:\n"
		pending=
		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 xd rz sd up wd vnd ccd"
for i in $DISKLIST; do
	egrep "^b.*/${i}[0-9][0-9]*[a-h]$"  $LIST >> $TMP1
	egrep "^c.*/r${i}[0-9][0-9]*[a-h]$"  $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

# 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 [ -d /etc/mtree ]; then
	cd /etc/mtree
	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 *.secure; do
		[ $file = '*.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
else
	echo /etc/mtree is missing
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 [ -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