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AIX7-00-001015 - The shipped /etc/security/mkuser.sys file on AIX must not be customized directly.

Information

The "/etc/security/mkuser.sys" script customizes the new user account when a new user is created, or a user is logging into the system without a home directory. An improper "/etc/security/mkuser.sys" script increases the risk that non-privileged users may obtain elevated privileges.

Solution

Edit the script /etc/security/mkuser.sys to contain the following:
# This file is no longer user customizable. To have a customized mkuser.sys script
# create a file /etc/security/mkuser.sys.custom and the /etc/security/mkuser.sys
# will run this script instead of the original mkuser.sys script.

export PATH=/usr/bin:/usr/sbin:$PATH

#
# Check the number of arguments first
#
if [ $# -ne 4 ]
then
 exit 1
fi

#
# If a customer mkuser.sys.custom script exists
# then execute it instead and exit passing all arguments
# and returning the return code from mkuser.sys.custom
#
if [ -x /etc/security/mkuser.sys.custom ]
then
 /etc/security/mkuser.sys.custom $*
 exit $?
fi

#
# Create the named directory if it does not already exist
# and set the file ownership and permission
#
if [ ! -d $1 ]
then
 last=$1

 while [ 1 ]
 do
 dir=`dirname $last`

 if [ -d $last ]
 then
 break
 elif [ -d $dir ]
 then
 mkdir -p $1
 chown -R bin:bin $last
 chmod -R 755 $last
 break
 else
 last=$dir
 fi
 done

 chgrp "$3" $1
 chown $2 $1
fi

#
# Copy the user's default .profile if it does not already
# exist and change the file ownership, etc.
#
if [ `basename $4` != "csh" ] && [ ! -f $1/.profile ]
then
 cp /etc/security/.profile $1/.profile
 chmod u+rwx,go-w $1/.profile
 chgrp "$3" $1/.profile
 chown $2 $1/.profile

else
 if [ `basename $4` = "csh" ] && [ ! -f $1/.login ]
 then
 echo "#!/bin/csh" > "$1"/.login
 echo "set path = ( /usr/bin /etc /usr/sbin /usr/ucb \$HOME/bin /usr/bin/X11 /sbin . )" >> "$1"/.login
 echo "setenv MAIL \"/var/spool/mail/\$LOGNAME\"" >> "$1"/.login
 echo "setenv MAILMSG \"[YOU HAVE NEW MAIL]\"" >> "$1"/.login
 echo "if ( -f \"\$MAIL\" && ! -z \"\$MAIL\") then" >> "$1"/.login
 echo " echo \"\$MAILMSG\"" >> "$1"/.login
 echo "endif" >> "$1"/.login
 chmod u+rwx,go-w $1/.login
 chgrp "$3" $1/.login
 chown $2 $1/.login
 fi
fi

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_IBM_AIX_7-x_V3R2_STIG.zip

Item Details

Category: ACCESS CONTROL

References: 800-53|AC-2(1), CAT|II, CCI|CCI-000015, Rule-ID|SV-215181r958362_rule, STIG-ID|AIX7-00-001015, STIG-Legacy|SV-101311, STIG-Legacy|V-91211, Vuln-ID|V-215181

Plugin: Unix

Control ID: 51bf96e08a3ee9010d9d82e52fd4b5bf459e4d26680e1f9371c569457ac64507