xref: /csrg-svn/etc/security (revision 53130)

#!/bin/sh -
#
#	@(#)security	5.16 (Berkeley) 04/06/92
#

# Script to check basic system security.  Checks included are:
#	Password and group file check.
#	Root umask, dot in root's path.
#	Root and uucp in /etc/ftpusers.
#	Entry for uudecode in /etc/aliases, if uudecode is setuid.
#	Hosts.equiv syntax.
#	Special users that have .rhosts files, .rhosts file syntax.
#	Home directory and dot-file ownership and permissions.
#	Mailbox ownership and permissions.
#	Globally exported NFS file systems.
#	Changes in setuid and device files.
#	Block and character disk device ownership and permissions.
#	File list from /etc/mtree/special.
#	System binaries as described by files in /etc/mtree.

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

umask 077

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

trap 'rm -f $ERR $TMP1 $TMP2 $TMP3 $LIST $OUTPUT' 0

# Check the 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 !~ /[A-za-z0-9]*/)
		printf("Login %s has non-numeric 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" && $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 user 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

# Check the group file syntax.
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-numeric 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 user 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.
> $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 aliases file.
if grep -w uudecode /etc/aliases; then
	printf "\nThere is an entry for uudecode in the /etc/aliases file.\n"
fi

# Check for plus signs in /etc/hosts.equiv.
if egrep '\+|^$' /etc/hosts.equiv > /dev/null ; then
	printf "\nEmpty line or + in /etc/hosts.equiv file.\n"
fi

# Check for special users with .rhosts files.  Only root and toor should
# have a .rhosts files.  Also, .rhosts files should not have blank lines
# or plus signs.
awk -F: '$1 != "root" && $1 != "toor" && \
	($3 < 100 || $1 == "ftp" || $1 == "uucp") \
		{ print $1 " " $6 }' /etc/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 " " $6 }' /etc/passwd | \
while read uid homedir; do
	if [ -f ${homedir}/.rhosts ] && \
	    egrep '\+|^$' ${homedir}/.rhosts > /dev/null ; then
		printf "$uid: empty line or + in .rhosts file.\n"
	fi
done > $OUTPUT
if [ -s $OUTPUT ] ; then
	printf "\nChecking .rhosts files syntax.\n"
	cat $OUTPUT
fi

# Check home directories, dot files.
# Directories should not be owned by someone else or writeable.
awk -F: '{ 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"
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 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 .emacsrc .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

# Check mailbox ownership and permissions.
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

# Check for globally exported file systems.
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

# Display setuid and device changes.
printf "\nChecking setuid files and devices:\n"
(find / ! -fstype local -a -prune -o \
    \( -perm -u+s -o -perm -g+s -o ! -type d -a ! -type f -a ! -type l -a \
       ! -type s \) | \
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"
		cat $TMP1
		printf "\n"
		cp $TMP1 $CUR
	fi
fi

# Check for readable/writeable block and character disk devices.
egrep '^b' $LIST > $TMP1
egrep '^c.*/rdk[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rfd[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rhd[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rhk[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rhp[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rjb[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rkra[0-9][0-9]*[a-h]$' $LIST >> $TMP1
egrep '^c.*/rra[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rrb[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rrd[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rrl[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rrx[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rrz[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rsd[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rup[0-9][0-9]*[a-h]$'  $LIST >> $TMP1
egrep '^c.*/rwd[0-9][0-9]*[a-h]$'  $LIST >> $TMP1

awk '$4 != "operator" \
	{ print "Disk " $11 " not owned by group operator." }
     $1 !~ /.rw-r-----/ \
	{ print "Disk " $11 " is " $1 ", group " $4 }' < $TMP1 > $OUTPUT
if [ -s $OUTPUT ] ; then
	printf "\nChecking disk ownership and permissions.\n"
	cat $OUTPUT
	printf "\n"
fi

egrep '^[bcs]' $LIST | sort +10 > $TMP1
# Display any changes in the device file list.
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

			sort +10 $TMP2 $CUR $TMP1 | \
			sed -e 's/[	 ][	 ]*/ /g' | \
			awk '{ \
			    printf("%s %s %s %s %s %s %s %s %s %s %s\n", \
			    $7, $8, $9, $10, $1, $2, $3, $4, $5, $6, $11); \
			    }' | uniq -f 4 -u | \
			awk '{ \
			    printf("%s %s %s %s %s %s %s %s %s %s %s\n", \
			    $5, $6, $7, $8, $9, $10, $1, $2, $3, $4, $11); \
			    }' > $OUTPUT
			if [ -s $OUTPUT ] ; then
				printf "Device changes:\n"
				column -t $OUTPUT
				printf "\n"
			fi

			cp $CUR $BACK
			cp $TMP1 $CUR
		fi
	else
		printf "Device additions:\n"
		cat $TMP1
		printf "\n"
		cp $TMP1 $CUR
	fi
fi

# Check the 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.
# Check for special files.

if cd /etc/mtree; 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 *.secure; do
		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