{"description": "SSH can emulate the behavior of the obsolete rsh\ncommand in allowing users to enable insecure access to their\naccounts via <tt>.rhosts</tt> files.\n<br />\nThe default SSH configuration disables support for <tt>.rhosts</tt>. The appropriate\nconfiguration is used if no value is set for <tt>IgnoreRhosts</tt>.\n<br/>\nTo explicitly disable support for .rhosts files, add or correct the following line in\n\n\n<tt>/etc/ssh/sshd_config.d/00-complianceascode-hardening.conf</tt>:\n\n<pre>IgnoreRhosts yes</pre>", "rationale": "SSH trust relationships mean a compromise on one host\ncan allow an attacker to move trivially to other hosts.", "severity": "medium", "references": {"cis-csc": ["11", "12", "14", "15", "16", "18", "3", "5", "9"], "cjis": ["5.5.6"], "cobit5": ["BAI10.01", "BAI10.02", "BAI10.03", "BAI10.05", "DSS05.02", "DSS05.04", "DSS05.05", "DSS05.07", "DSS06.03", "DSS06.06"], "cui": ["3.1.12"], "isa-62443-2009": ["4.3.3.2.2", "4.3.3.5.1", "4.3.3.5.2", "4.3.3.5.3", "4.3.3.5.4", "4.3.3.5.5", "4.3.3.5.6", "4.3.3.5.7", "4.3.3.5.8", "4.3.3.6.1", "4.3.3.6.2", "4.3.3.6.3", "4.3.3.6.4", "4.3.3.6.5", "4.3.3.6.6", "4.3.3.6.7", "4.3.3.6.8", "4.3.3.6.9", "4.3.3.7.1", "4.3.3.7.2", "4.3.3.7.3", "4.3.3.7.4", "4.3.4.3.2", "4.3.4.3.3"], "isa-62443-2013": ["SR 1.1", "SR 1.10", "SR 1.11", "SR 1.12", "SR 1.13", "SR 1.2", "SR 1.3", "SR 1.4", "SR 1.5", "SR 1.6", "SR 1.7", "SR 1.8", "SR 1.9", "SR 2.1", "SR 2.2", "SR 2.3", "SR 2.4", "SR 2.5", "SR 2.6", "SR 2.7", "SR 7.6"], "iso27001-2013": ["A.12.1.2", "A.12.5.1", "A.12.6.2", "A.14.2.2", "A.14.2.3", "A.14.2.4", "A.6.1.2", "A.7.1.1", "A.9.1.2", "A.9.2.1", "A.9.2.3", "A.9.4.1", "A.9.4.4", "A.9.4.5"], "nist": ["AC-17(a)", "CM-7(a)", "CM-7(b)", "CM-6(a)"], "nist-csf": ["PR.AC-4", "PR.AC-6", "PR.IP-1", "PR.PT-3"], "srg": ["SRG-OS-000480-GPOS-00227"], "cis": ["5.1.11"], "ism": ["1546"], "pcidss4": ["2.2.6", "2.2"]}, "control_references": {"cis": ["5.1.11"], "ism": ["1546"], "pcidss4": ["2.2.6", "2.2"]}, "components": [], "identifiers": {}, "ocil_clause": "the required value is not set", "ocil": "To determine how the SSH daemon's <tt>IgnoreRhosts</tt> option is set, run the following command:\n\n<pre>$ sudo grep -i IgnoreRhosts /etc/ssh/sshd_config.d/00-complianceascode-hardening.conf</pre>\n<pre>$ sudo grep -i IgnoreRhosts /etc/ssh/sshd_config.d/01-complianceascode-reinforce-os-defaults.conf</pre>\n\nIf a line indicating <tt>yes</tt> is returned, then the required value is set.\n", "oval_external_content": null, "fixtext": "To configure the system add or modify the following line in \"/etc/ssh/sshd_config\".\n\nIgnoreRhosts yes\n\nRestart the SSH daemon for the settings to take effect:\n\n$ sudo systemctl restart sshd.service", "checktext": "", "vuldiscussion": "", "srg_requirement": " must be configured so that the SSH daemon does not allow authentication using rhosts authentication.", "warnings": [], "conflicts": [], "requires": [], "policy_specific_content": {"stig": {"srg_requirement": "Ubuntu 22.04 SSH daemon must not allow rhosts authentication.", "vuldiscussion": "SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.", "checktext": "Verify the SSH daemon does not allow rhosts authentication with the following command:\n\n$ sudo /usr/sbin/sshd -dd 2&gt;&1 | awk '/filename/ {print $4}' | tr -d '\\r' | tr '\\n' ' ' | xargs sudo grep -iH '^\\s*ignorerhosts'\n\nIgnoreRhosts yes\n\nIf the value is returned as \"no\", the returned line is commented out, or no output is returned, this is a finding.", "fixtext": "Configure the SSH daemon to not allow rhosts authentication.\n\nAdd the following line to \"/etc/ssh/sshd_config\" or to a file in \"/etc/ssh/sshd_config.d\", or uncomment the line and set the value to \"yes\":\n\nIgnoreRhosts yes\n\nThe SSH service must be restarted for changes to take effect:\n\n$ sudo systemctl restart sshd.service"}}, "platform": null, "platforms": [], "sce_metadata": {}, "inherited_platforms": ["system_with_kernel"], "cpe_platform_names": [], "inherited_cpe_platform_names": ["system_with_kernel"], "bash_conditional": null, "fixes": {}, "title": "Disable SSH Support for .rhosts Files", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/services/ssh/ssh_server/sshd_disable_rhosts/rule.yml", "template": {"name": "sshd_lineinfile", "vars": {"parameter": "IgnoreRhosts", "value": "yes", "datatype": "string", "is_default_value": "true"}, "backends": {}}}