usr/src/etc/security

#!/bin/sh -
#
#       @(#)security    5.28 (Berkeley) %G%
#

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 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 ($1 !~ /^[A-Za-z0-9]*$/)
                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" && $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

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.
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 (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/hosts.lpd"
for f in $list ; do
        if 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 a .rhosts files.  Also, .rhosts files should not 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: + in .rhosts file.\n"
        fi
done > $OUTPUT
if [ -s $OUTPUT ] ; then
        printf "\nChecking .rhosts files syntax.\n"
        cat $OUTPUT
fi

# Check home directories.  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

# 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

# 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

# Display any changes in setuid files and devices.
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"
                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"
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 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

# 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