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Guide to the Secure Configuration of Alibaba Cloud Linux 2

Rules, Groups, and Values defined within the XCCDF Benchmark

  • All GIDs referenced in /etc/passwd must be defined in /etc/group

    Add a group to the system for each GID referenced without a corresponding group.
    Rule Low Severity
  • Prevent Login to Accounts With Empty Password

    If an account is configured for password authentication but does not have an assigned password, it may be possible to log into the account without ...
    Rule High Severity
  • Ensure There Are No Accounts With Blank or Null Passwords

    Check the "/etc/shadow" file for blank passwords with the following command: <pre>$ sudo awk -F: '!$2 {print $1}' /etc/shadow</pre> If the command ...
    Rule High Severity
  • Restrict Root Logins

    Direct root logins should be allowed only for emergency use. In normal situations, the administrator should access the system via a unique unprivil...
    Group
  • Group Name Used by pam_wheel Group Parameter

    pam_wheel module has a parameter called group, which controls which groups can access the su command. This variable holds the valid value for the p...
    Value
  • Verify Only Root Has UID 0

    If any account other than root has a UID of 0, this misconfiguration should be investigated and the accounts other than root should be removed or h...
    Rule High Severity
  • Verify Root Has A Primary GID 0

    The root user should have a primary group of 0.
    Rule High Severity
  • Direct root Logins Not Allowed

    To further limit access to the <code>root</code> account, administrators can disable root logins at the console by editing the <code>/etc/securetty...
    Rule Medium Severity
  • Ensure that System Accounts Do Not Run a Shell Upon Login

    Some accounts are not associated with a human user of the system, and exist to perform some administrative functions. Should an attacker be able to...
    Rule Medium Severity
  • Restrict Serial Port Root Logins

    To restrict root logins on serial ports, ensure lines of this form do not appear in /etc/securetty:
    ttyS0
    ttyS1
    Rule Medium Severity
  • Restrict Virtual Console Root Logins

    To restrict root logins through the (deprecated) virtual console devices, ensure lines of this form do not appear in <code>/etc/securetty</code>: <...
    Rule Medium Severity
  • Secure Session Configuration Files for Login Accounts

    When a user logs into a Unix account, the system configures the user's session by reading a number of files. Many of these files are located in the...
    Group
  • Maximum login attempts delay

    Maximum time in seconds between fail login attempts before re-prompting.
    Value
  • Maximum concurrent login sessions

    Maximum number of concurrent sessions by a user
    Value
  • Account Inactivity Timeout (seconds)

    In an interactive shell, the value is interpreted as the number of seconds to wait for input after issuing the primary prompt. Bash terminates afte...
    Value
  • Interactive users initialization files

    'A regular expression describing a list of file names for files that are sourced at login time for interactive users'
    Value
  • Ensure the Logon Failure Delay is Set Correctly in login.defs

    To ensure the logon failure delay controlled by <code>/etc/login.defs</code> is set properly, add or correct the <code>FAIL_DELAY</code> setting in...
    Rule Medium Severity
  • Limit the Number of Concurrent Login Sessions Allowed Per User

    Limiting the number of allowed users and sessions per user can limit risks related to Denial of Service attacks. This addresses concurrent sessions...
    Rule Low Severity
  • Configure Polyinstantiation of /tmp Directories

    To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use th...
    Rule Low Severity
  • Configure Polyinstantiation of /var/tmp Directories

    To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use th...
    Rule Low Severity
  • Ensure that User Home Directories are not Group-Writable or World-Readable

    For each human user of the system, view the permissions of the user's home directory: <pre># ls -ld /home/<i>USER</i></pre> Ensure that the directo...
    Rule Medium Severity
  • Ensure that No Dangerous Directories Exist in Root's Path

    The active path of the root account can be obtained by starting a new root shell and running: <pre># echo $PATH</pre> This will produce a colon-sep...
    Group
  • Ensure that Users Have Sensible Umask Values

    The umask setting controls the default permissions for the creation of new files. With a default <code>umask</code> setting of 077, files and direc...
    Group
  • Sensible umask

    Enter default user umask
    Value
  • System Accounting with auditd

    The audit service provides substantial capabilities for recording system activities. By default, the service audits about SELinux AVC denials and c...
    Group
  • Ensure the audit Subsystem is Installed

    The audit package should be installed.
    Rule Medium Severity
  • Enable auditd Service

    The <code>auditd</code> service is an essential userspace component of the Linux Auditing System, as it is responsible for writing audit records to...
    Rule Medium Severity
  • Enable Auditing for Processes Which Start Prior to the Audit Daemon

    To ensure all processes can be audited, even those which start prior to the audit daemon, add the argument <code>audit=1</code> to the default GRUB...
    Rule Low Severity
  • Configure auditd Rules for Comprehensive Auditing

    The <code>auditd</code> program can perform comprehensive monitoring of system activity. This section describes recommended configuration settings ...
    Group
  • Audit failure mode

    This variable is the setting for the -f option in Audit configuration which sets the failure mode of audit. This option lets you determine how you ...
    Value
  • Make the auditd Configuration Immutable

    If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...
    Rule Medium Severity
  • Record Events that Modify the System's Mandatory Access Controls

    If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...
    Rule Medium Severity
  • Record Events that Modify the System's Mandatory Access Controls in usr/share

    If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...
    Rule Medium Severity
  • Ensure auditd Collects Information on Exporting to Media (successful)

    At a minimum, the audit system should collect media exportation events for all users and root. If the <code>auditd</code> daemon is configured to u...
    Rule Medium Severity
  • Record Events that Modify the System's Network Environment

    If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...
    Rule Medium Severity
  • Record Attempts to Alter Process and Session Initiation Information

    The audit system already collects process information for all users and root. If the <code>auditd</code> daemon is configured to use the <code>auge...
    Rule Medium Severity
  • Ensure auditd Collects System Administrator Actions

    At a minimum, the audit system should collect administrator actions for all users and root. If the <code>auditd</code> daemon is configured to use ...
    Rule Medium Severity
  • The percentage remaining in disk space before prompting space_left_action

    The setting for space_left as a percentage in /etc/audit/auditd.conf
    Value
  • Kernel panic timeout

    The time, in seconds, to wait until a reboot occurs. If the value is <code>0</code> the system never reboots. If the value is less than <code>0</co...
    Value
  • cobbler_use_cifs SELinux Boolean

    default - Default SELinux boolean setting.
    on - SELinux boolean is enabled.
    off - SELinux boolean is disabled.
    Value
  • Record Events that Modify User/Group Information

    If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...
    Rule Medium Severity
  • Record Events that Modify User/Group Information - /etc/group

    If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...
    Rule Medium Severity
  • Verify Permissions on passwd File

    To properly set the permissions of /etc/passwd, run the command:
    $ sudo chmod 0644 /etc/passwd
    Rule Medium Severity
  • Verify Permissions on shadow File

    To properly set the permissions of /etc/shadow, run the command:
    $ sudo chmod 0000 /etc/shadow
    Rule Medium Severity
  • Verify Permissions on Files within /var/log Directory

    The /var/log directory contains files with logs of error messages in the system and should only be accessed by authorized personnel.
    Group
  • Verify Group Who Owns /var/log Directory

    To properly set the group owner of /var/log, run the command:
    $ sudo chgrp root /var/log
    Rule Medium Severity
  • Verify Group Who Owns /var/log/messages File

    To properly set the group owner of /var/log/messages, run the command:
    $ sudo chgrp root /var/log/messages
    Rule Medium Severity
  • Verify Group Who Owns /var/log/syslog File

    To properly set the group owner of /var/log/syslog, run the command:
    $ sudo chgrp adm /var/log/syslog
    Rule Medium Severity
  • Verify User Who Owns /var/log Directory

    To properly set the owner of /var/log, run the command:
    $ sudo chown root /var/log 
    Rule Medium Severity
  • Verify User Who Owns /var/log/messages File

    To properly set the owner of /var/log/messages, run the command:
    $ sudo chown root /var/log/messages 
    Rule Medium Severity

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