Recovering AWS instance that is prompting for password (happens when using SSH Key only logins)

recover cloud init password aws reset password instance remount cloud-init

Part of this is directly cribbed from AWS Docs!

Symptoms:

Password change required but no TTY available.

WARNING: Your password has expired

Logging in with SSH but getting prompted to change your password for cloud-user, and those are random to begin with, so can’t change it cuz you don’t know it

Problem:

cloud-user account password has expired. account expiry has nothing to do with ssh key validity, as shown by getting connected and then getting the change password prompt (you’re already in via SSH, but PAM kicks in to force the password change)

Fix:

Stop the instance (sorry)(do not terminate!)

Copy out user data

Replace user-data with this:

Content-Type: multipart/mixed; boundary=”//”

MIME-Version: 1.0

<span style="font-size: 14px; color: rgb(51, 51, 51); font-family: Consolas, "Andale Mono WT", "Andale Mono", "Lucida Console", "Lucida Sans Typewriter", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Liberation Mono", "Nimbus Mono L", Monaco, "Courier New", Courier, monospace; font-variant-caps: normal; font-variant-ligatures: normal; line-height: 1.6em;"–<//

Content-Type: text/cloud-config; charset=”us-ascii”

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Content-Disposition: attachment; filename=”cloud-config.txt”

#cloud-config

cloud_final_modules:

– [scripts-user, always]

<span style="font-size: 14px; color: rgb(51, 51, 51); font-family: Consolas, "Andale Mono WT", "Andale Mono", "Lucida Console", "Lucida Sans Typewriter", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Liberation Mono", "Nimbus Mono L", Monaco, "Courier New", Courier, monospace; font-variant-caps: normal; font-variant-ligatures: normal; line-height: 1.6em;"–<//

Content-Type: text/x-shellscript; charset=”us-ascii”

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Content-Disposition: attachment; filename=”userdata.txt”

#!/bin/bash

/usr/bin/chage -d 65535 cloud-user

<span style="font-size: 14px; color: rgb(51, 51, 51); font-family: Consolas, "Andale Mono WT", "Andale Mono", "Lucida Console", "Lucida Sans Typewriter", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Liberation Mono", "Nimbus Mono L", Monaco, "Courier New", Courier, monospace; font-variant-caps: normal; font-variant-ligatures: normal; line-height: 1.6em;"–<//

start the instance again

WAIT AT LEAST ONE MINUTE!!

User data happens async from when the box starts up, so sit tight a minute or two.

SSH login should now work

Do you need to put your user data back?

You have to stop the instance to replace the user-data section, and it will fire again on startup. Decide if this is what you need, or leave it as is, or stop it and blank out user data.

If you replace your user-data to what it was before, add this section to prevent this from recurring:

# Fix the cloud-user password age issue

sed -i.bak -e ‘/Defaults.*requiretty/s/^/#/’ /etc/sudoers

chage -d 65535 cloud-user

Ok, so, scripted version:

You need:

my-user-data (below)

aws-replace-user-data.sh (below)

aws cli installed and working

aws-saml-auth installed and working

my-user-data:

#cloud-boothook

Content-Type: multipart/mixed; boundary=”//”

MIME-Version: 1.0

–//

Content-Type: text/cloud-config; charset=”us-ascii”

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Content-Disposition: attachment; filename=”cloud-config.txt”

#cloud-config

cloud_final_modules:

– [scripts-user, always]

–//

Content-Type: text/x-shellscript; charset=”us-ascii”

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Content-Disposition: attachment; filename=”userdata.txt”

#!/bin/bash -x

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

groupadd -g 25638 rundeck

#adduser -g rundeck rundeck

useradd -p $(openssl passwd -1 9837y45fhyiwurhef84yf93y4978yhfh) -g rundeck rundeck

echo “9837y45fhyiwurhef84yf93y4978yhfh” | passwd –stdin rundeck

usermod -c “Rundeck Service Account.” -u 35638 rundeck

usermod rundeck -G wheel

gpasswd -a rundeck wheel

getent passwd rundeck > /dev/null 2&>1

if [ $? -eq 0 ]; then

    chage -I -1 -m 0 -M 99999 -E -1 rundeck

else

    echo “Skipping, user does not exist”

fi

getent passwd cloudse > /dev/null 2&>1

if [ $? -eq 0 ]; then

    chage -I -1 -m 0 -M 99999 -E -1 cloudse

else

    echo “Skipping, user does not exist”

fi

getent passwd cloud-user > /dev/null 2&>1

if [ $? -eq 0 ]; then

    chage -I -1 -m 0 -M 99999 -E -1 cloud-user

else

    echo “Skipping, user does not exist”

fi

getent passwd ec2-user > /dev/null 2&>1

if [ $? -eq 0 ]; then

    chage -I -1 -m 0 -M 99999 -E -1 ec2-user

else

    echo “Skipping, user does not exist”

fi

# chage failures make the cloud-init fail, so use the logic blocks above

# chage -I -1 -m 0 -M 99999 -E -1 rundeck

# Fix rundeck sudo privs

rm -f /etc/sudoers.d/rundeck

cat > “/etc/sudoers.d/rundeck” << EOF

# This file is managed by Chef.

# Do NOT modify this file directly.

%rundeck ALL=(ALL) NOPASSWD:ALL

Defaults:%rundeck !requiretty

EOF

# Rundeck env setup

mkdir -p /home/rundeck/.ssh/

chown -R rundeck:rundeck /home/rundeck

rm -f /home/rundeck/.ssh/authorized_keys

# Add Rundeck key

cat > “/home/rundeck/.ssh/authorized_keys” << EOF

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAzxyMM1ozCoxZNe0q7PeiJdtqUQc6VKhAY46dmDET4Q+lvcmkDdE3q8IVCkrI8MES2j9YBoCy00BV3kAWRDTilq0CArDSVpTp5lz/2Fgu/EaxTMQKk2XiGGW4M4QUkAQRgHDNT1k8lYIhRENFS8Csf9Bt2lFOgWH18sw7s4GuCULbBfDZdsMVHN6wctv0j2vbvcPdg+QX2gg7TY4HdWoDQ3OSOrWSyAeseXA81h3+OZSKhyFmTIFzk0+8uxuv18CdilfyhCiDJqGwVV5WpbOTXlimT92ea6R5V1H8KeuhZEMnpuiCUjbQzGKuUsbKHu+bVWQqQMh9VS9VlC9Q0kqxFw==

EOF

chmod -R 600 /home/rundeck/.ssh/authorized_keys

chown -R rundeck:rundeck /home/rundeck/.ssh/authorized_keys

chmod -R 600  /var/spool/mail/rundeck

chown -R rundeck:rundeck  /var/spool/mail/rundeck

chmod 440 /etc/sudoers.d/rundeck

# Temporary

# echo rundeck:8y5g9eyhrgy3875ty98374hfjhwef | chpasswd

touch /root/cloud-init-fix-was-here

–//

aws-replace-user-data.sh:

#!/bin/bash

EXPECTED_ARGS=6

E_BADARGS=65

if [ $# -ne $EXPECTED_ARGS ]

then

        echo “All parameters are required, in any order:”

        echo “-i instance_id ( i-0b1fd14e321099e6d )”

        echo “-r region ( us-east-1, us-west-2, etc )”

        echo “-f filename ( aws-recovery-user-data in current path )”

  exit $E_BADARGS

fi

while getopts “:i:r:f:” opt; do

  case $opt in

    i)

      echo “-i was triggered, Parameter: $OPTARG” >&2;

        INSTANCE=$OPTARG;

      ;;

    r)

      echo “-r was triggered, Parameter: $OPTARG” >&2;

        REGION=$OPTARG;

      ;;

    f)

      echo “-f was triggered, Parameter: $OPTARG” >&2;

        FILENAME=$OPTARG;

      ;;

    *)

      echo “Invalid option: -$OPTARG” >&2

        echo Example: ./aws-replace-user-data.sh -i i-0b1fd14e321099e6d -r us-west-2

      exit 1

        break

      ;;

    🙂

      echo “Option -$OPTARG requires an argument.” >&2

        echo Example: ./aws-replace-user-data.sh -i i-0b1fd14e321099e6d -r us-west-2 -f my-user-data

      exit 1

        break

      ;;

  esac

done

# You can preset or override some things if its your machine

echo Using instance ID: ${INSTANCE}

echo Using region: ${REGION}

echo Using filename: ${FILENAME}

# aws-saml-auth

# pip install –upgrade –user awscli

# Stop

aws ec2 –region ${REGION} stop-instances –instance-ids ${INSTANCE}

# Better!

while [ true ]

    do  aws ec2 describe-instances –filter “Name=instance-state-name,Values=stopped” –region ${REGION} –instance-id ${INSTANCE} |grep stopped && break

    echo Not stopped yet

    sleep 5

    echo retrying…

done

# Base64 encode your file:

echo “Encoding ” ${FILENAME}

rm -f ${FILENAME}.base64

base64 ${FILENAME} >> ${FILENAME}.base64

# Modify!

echo “Modifying instance: “

aws ec2 modify-instance-attribute –region ${REGION} –attribute userData –value file://${FILENAME}.base64 –instance-id ${INSTANCE}

# Start

echo “Starting instance: “

aws ec2 –region ${REGION} start-instances –instance-ids ${INSTANCE}

# Optional

while [ true ]

    do  aws ec2 describe-instances –filter “Name=instance-state-name,Values=running” –region ${REGION} –instance-id ${INSTANCE} |grep running && break

    echo Not started yet

    sleep 5

    echo retrying…

done

Usage:

./aws-replace-user-data.sh -i i-050bea589a55ac039 -r us-west-2 -f my-user-data

punch it in the face backdoor:

Content-Type: multipart/mixed; boundary=”//”

MIME-Version: 1.0

–//

Content-Type: text/cloud-config; charset=”us-ascii”

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Content-Disposition: attachment; filename=”cloud-config.txt”

#cloud-config

cloud_final_modules:

– [scripts-user, always]

–//

Content-Type: text/x-shellscript; charset=”us-ascii”

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Content-Disposition: attachment; filename=”userdata.txt”

#!/bin/bash

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

useradd -p $(openssl passwd -1 9837y45fhyiwurhef84yf93y4978yhfh) backdoor

echo “9837y45fhyiwurhef84yf93y4978yhfh” | passwd –stdin backdoor

usermod -c “Recovery account, please remove.”  backdoor

usermod backdoor -G wheel

gpasswd -a backdoor wheel

<span style="font-size: 14px;"–<//

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