Set Deny For Failed Password Attempts
Cette page n'est pas encore disponible en français, sa traduction est en cours.
Si vous avez des questions ou des retours sur notre projet de traduction actuel,
n'hésitez pas à nous contacter.
Description
The Ubuntu 20.04 operating system must lock an account after - at most - 5
consecutive invalid access attempts.
Rationale
By limiting the number of failed logon attempts, the risk of unauthorized
system access via user password guessing, otherwise known as brute-force
attacks, is reduced. Limits are imposed by locking the account.
To configure the operating system to lock an account after three
unsuccessful consecutive access attempts using pam_tally2.so,
modify the content of both /etc/pam.d/common-auth and
/etc/pam.d/common-account as follows:
- add or modify the
pam_tally2.so module line in
/etc/pam.d/common-auth to ensure both onerr=fail and
deny=5 are present. For example:auth required pam_tally2.so onerr=fail silent audit deny=5
- add or modify the following line in
/etc/pam.d/common-account:account required pam_tally2.so
Shell script
The following script can be run on the host to remediate the issue.
#!/bin/bash
# Remediation is applicable only in certain platforms
if dpkg-query --show --showformat='${db:Status-Status}\n' 'libpam-runtime' 2>/dev/null | grep -q installed; then
var_password_pam_tally2='5'
# Use a non-number regexp to force update of the value of the deny option
if ! grep -qP "^\s*auth\s+required\s+pam_tally2.so\s*.*" "/etc/pam.d/common-auth"; then
# Line matching group + control + module was not found. Check group + module.
if [ "$(grep -cP '^\s*auth\s+.*\s+pam_tally2.so\s*' "/etc/pam.d/common-auth")" -eq 1 ]; then
# The control is updated only if one single line matches.
sed -i -E --follow-symlinks "s/^(\s*auth\s+).*(\bpam_tally2.so.*)/\1required \2/" "/etc/pam.d/common-auth"
else
echo "auth required pam_tally2.so" >> "/etc/pam.d/common-auth"
fi
fi
# Check the option
if ! grep -qP "^\s*auth\s+required\s+pam_tally2.so\s*.*\sdeny\b" "/etc/pam.d/common-auth"; then
sed -i -E --follow-symlinks "/\s*auth\s+required\s+pam_tally2.so.*/ s/$/ deny=${var_password_pam_tally2}/" "/etc/pam.d/common-auth"
else
sed -i -E --follow-symlinks "s/(\s*auth\s+required\s+pam_tally2.so\s+.*)(deny=)[[:alnum:]]+\s*(.*)/\1\2${var_password_pam_tally2} \3/" "/etc/pam.d/common-auth"
fi
if ! grep -qP "^\s*auth\s+required\s+pam_tally2.so\s*.*" "/etc/pam.d/common-auth"; then
# Line matching group + control + module was not found. Check group + module.
if [ "$(grep -cP '^\s*auth\s+.*\s+pam_tally2.so\s*' "/etc/pam.d/common-auth")" -eq 1 ]; then
# The control is updated only if one single line matches.
sed -i -E --follow-symlinks "s/^(\s*auth\s+).*(\bpam_tally2.so.*)/\1required \2/" "/etc/pam.d/common-auth"
else
LAST_MATCH_LINE=$(grep -nP "(fail)" "/etc/pam.d/common-auth" | tail -n 1 | cut -d: -f 1)
if [ ! -z $LAST_MATCH_LINE ]; then
sed -i --follow-symlinks $LAST_MATCH_LINE" a auth required pam_tally2.so" "/etc/pam.d/common-auth"
else
echo "auth required pam_tally2.so" >> "/etc/pam.d/common-auth"
fi
fi
fi
# Check the option
if ! grep -qP "^\s*auth\s+required\s+pam_tally2.so\s*.*\sonerr\b" "/etc/pam.d/common-auth"; then
sed -i -E --follow-symlinks "/\s*auth\s+required\s+pam_tally2.so.*/ s/$/ onerr=fail/" "/etc/pam.d/common-auth"
else
sed -i -E --follow-symlinks "s/(\s*auth\s+required\s+pam_tally2.so\s+.*)(onerr=)[[:alnum:]]+\s*(.*)/\1\2fail \3/" "/etc/pam.d/common-auth"
fi
if ! grep -qP "^\s*account\s+required\s+pam_tally2.so\s*.*" "/etc/pam.d/common-account"; then
# Line matching group + control + module was not found. Check group + module.
if [ "$(grep -cP '^\s*account\s+.*\s+pam_tally2.so\s*' "/etc/pam.d/common-account")" -eq 1 ]; then
# The control is updated only if one single line matches.
sed -i -E --follow-symlinks "s/^(\s*account\s+).*(\bpam_tally2.so.*)/\1required \2/" "/etc/pam.d/common-account"
else
echo "account required pam_tally2.so" >> "/etc/pam.d/common-account"
fi
fi
# Check the option
if ! grep -qP "^\s*account\s+required\s+pam_tally2.so\s*.*\s\b" "/etc/pam.d/common-account"; then
sed -i -E --follow-symlinks "/\s*account\s+required\s+pam_tally2.so.*/ s/$/ /" "/etc/pam.d/common-account"
fi
else
>&2 echo 'Remediation is not applicable, nothing was done'
fi
Ansible playbook
The following playbook can be run with Ansible to remediate the issue.
- name: Gather the package facts
package_facts:
manager: auto
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: XCCDF Value var_password_pam_tally2 # promote to variable
set_fact:
var_password_pam_tally2: !!str 5
tags:
- always
- name: Set Deny For Failed Password Attempts - Define a fact for control already
filtered in case filters are used
ansible.builtin.set_fact:
pam_module_control: required
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Check if expected PAM module line
is present in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
regexp: ^\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s*.*
state: absent
check_mode: true
changed_when: false
register: result_pam_line_present
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Include or update the PAM module line
in /etc/pam.d/common-auth
block:
- name: Set Deny For Failed Password Attempts - Check if required PAM module line
is present in /etc/pam.d/common-auth with different control
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
regexp: ^\s*auth\s+.*\s+pam_tally2.so\s*
state: absent
check_mode: true
changed_when: false
register: result_pam_line_other_control_present
- name: Set Deny For Failed Password Attempts - Ensure the correct control for the
required PAM module line in /etc/pam.d/common-auth
ansible.builtin.replace:
dest: /etc/pam.d/common-auth
regexp: ^(\s*auth\s+).*(\bpam_tally2.so.*)
replace: \1{{ pam_module_control }} \2
register: result_pam_module_edit
when:
- result_pam_line_other_control_present.found == 1
- name: Set Deny For Failed Password Attempts - Ensure the required PAM module line
is included in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
dest: /etc/pam.d/common-auth
line: auth {{ pam_module_control }} pam_tally2.so
register: result_pam_module_add
when:
- result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
> 1
- name: Set Deny For Failed Password Attempts - Ensure authselect changes are applied
ansible.builtin.command:
cmd: authselect apply-changes -b
when:
- result_authselect_present is defined
- result_authselect_present.stat.exists
- |-
(result_pam_module_add is defined and result_pam_module_add.changed)
or (result_pam_module_edit is defined and result_pam_module_edit.changed)
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_line_present.found is defined
- result_pam_line_present.found == 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Define a fact for control already
filtered in case filters are used
ansible.builtin.set_fact:
pam_module_control: required
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Check if the required PAM module option
is present in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
regexp: ^\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s*.*\sdeny\b
state: absent
check_mode: true
changed_when: false
register: result_pam_module_accounts_passwords_pam_tally2_option_present
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Ensure the "deny" PAM option for "pam_tally2.so"
is included in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
backrefs: true
regexp: ^(\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so.*)
line: \1 deny={{ var_password_pam_tally2 }}
state: present
register: result_pam_accounts_passwords_pam_tally2_add
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_module_accounts_passwords_pam_tally2_option_present.found == 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Ensure the required value for "deny"
PAM option from "pam_tally2.so" in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
backrefs: true
regexp: ^(\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s+.*)(deny)=[0-9a-zA-Z]+\s*(.*)
line: \1\2={{ var_password_pam_tally2 }} \3
register: result_pam_accounts_passwords_pam_tally2_edit
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_module_accounts_passwords_pam_tally2_option_present.found > 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Define a fact for control already
filtered in case filters are used
ansible.builtin.set_fact:
pam_module_control: required
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Check if expected PAM module line
is present in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
regexp: ^\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s*.*
state: absent
check_mode: true
changed_when: false
register: result_pam_line_present
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Include or update the PAM module line
in /etc/pam.d/common-auth
block:
- name: Set Deny For Failed Password Attempts - Check if required PAM module line
is present in /etc/pam.d/common-auth with different control
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
regexp: ^\s*auth\s+.*\s+pam_tally2.so\s*
state: absent
check_mode: true
changed_when: false
register: result_pam_line_other_control_present
- name: Set Deny For Failed Password Attempts - Ensure the correct control for the
required PAM module line in /etc/pam.d/common-auth
ansible.builtin.replace:
dest: /etc/pam.d/common-auth
regexp: ^(\s*auth\s+).*(\bpam_tally2.so.*)
replace: \1{{ pam_module_control }} \2
register: result_pam_module_edit
when:
- result_pam_line_other_control_present.found == 1
- name: Set Deny For Failed Password Attempts - Ensure the required PAM module line
is included in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
dest: /etc/pam.d/common-auth
insertafter: (fail)
line: auth {{ pam_module_control }} pam_tally2.so
register: result_pam_module_add
when:
- result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
> 1
- name: Set Deny For Failed Password Attempts - Ensure authselect changes are applied
ansible.builtin.command:
cmd: authselect apply-changes -b
when:
- result_authselect_present is defined
- result_authselect_present.stat.exists
- |-
(result_pam_module_add is defined and result_pam_module_add.changed)
or (result_pam_module_edit is defined and result_pam_module_edit.changed)
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_line_present.found is defined
- result_pam_line_present.found == 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Define a fact for control already
filtered in case filters are used
ansible.builtin.set_fact:
pam_module_control: required
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Check if the required PAM module option
is present in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
regexp: ^\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s*.*\sonerr\b
state: absent
check_mode: true
changed_when: false
register: result_pam_module_accounts_passwords_pam_tally2_option_present
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Ensure the "onerr" PAM option for
"pam_tally2.so" is included in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
backrefs: true
regexp: ^(\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so.*)
line: \1 onerr=fail
state: present
register: result_pam_accounts_passwords_pam_tally2_add
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_module_accounts_passwords_pam_tally2_option_present.found == 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Ensure the required value for "onerr"
PAM option from "pam_tally2.so" in /etc/pam.d/common-auth
ansible.builtin.lineinfile:
path: /etc/pam.d/common-auth
backrefs: true
regexp: ^(\s*auth\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s+.*)(onerr)=[0-9a-zA-Z]+\s*(.*)
line: \1\2=fail \3
register: result_pam_accounts_passwords_pam_tally2_edit
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_module_accounts_passwords_pam_tally2_option_present.found > 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Define a fact for control already
filtered in case filters are used
ansible.builtin.set_fact:
pam_module_control: required
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Check if expected PAM module line
is present in /etc/pam.d/common-account
ansible.builtin.lineinfile:
path: /etc/pam.d/common-account
regexp: ^\s*account\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s*.*
state: absent
check_mode: true
changed_when: false
register: result_pam_line_present
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Include or update the PAM module line
in /etc/pam.d/common-account
block:
- name: Set Deny For Failed Password Attempts - Check if required PAM module line
is present in /etc/pam.d/common-account with different control
ansible.builtin.lineinfile:
path: /etc/pam.d/common-account
regexp: ^\s*account\s+.*\s+pam_tally2.so\s*
state: absent
check_mode: true
changed_when: false
register: result_pam_line_other_control_present
- name: Set Deny For Failed Password Attempts - Ensure the correct control for the
required PAM module line in /etc/pam.d/common-account
ansible.builtin.replace:
dest: /etc/pam.d/common-account
regexp: ^(\s*account\s+).*(\bpam_tally2.so.*)
replace: \1{{ pam_module_control }} \2
register: result_pam_module_edit
when:
- result_pam_line_other_control_present.found == 1
- name: Set Deny For Failed Password Attempts - Ensure the required PAM module line
is included in /etc/pam.d/common-account
ansible.builtin.lineinfile:
dest: /etc/pam.d/common-account
line: account {{ pam_module_control }} pam_tally2.so
register: result_pam_module_add
when:
- result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
> 1
- name: Set Deny For Failed Password Attempts - Ensure authselect changes are applied
ansible.builtin.command:
cmd: authselect apply-changes -b
when:
- result_authselect_present is defined
- result_authselect_present.stat.exists
- |-
(result_pam_module_add is defined and result_pam_module_add.changed)
or (result_pam_module_edit is defined and result_pam_module_edit.changed)
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_line_present.found is defined
- result_pam_line_present.found == 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Define a fact for control already
filtered in case filters are used
ansible.builtin.set_fact:
pam_module_control: required
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Check if the required PAM module option
is present in /etc/pam.d/common-account
ansible.builtin.lineinfile:
path: /etc/pam.d/common-account
regexp: ^\s*account\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so\s*.*\s\b
state: absent
check_mode: true
changed_when: false
register: result_pam_module_accounts_passwords_pam_tally2_option_present
when: '"libpam-runtime" in ansible_facts.packages'
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Set Deny For Failed Password Attempts - Ensure the "" PAM option for "pam_tally2.so"
is included in /etc/pam.d/common-account
ansible.builtin.lineinfile:
path: /etc/pam.d/common-account
backrefs: true
regexp: ^(\s*account\s+{{ pam_module_control | regex_escape() }}\s+pam_tally2.so.*)
line: \1
state: present
register: result_pam_accounts_passwords_pam_tally2_add
when:
- '"libpam-runtime" in ansible_facts.packages'
- result_pam_module_accounts_passwords_pam_tally2_option_present.found == 0
tags:
- PCI-DSS-Req-8.1.6
- PCI-DSSv4-8.3
- PCI-DSSv4-8.3.4
- accounts_passwords_pam_tally2
- configure_strategy
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
