{"description": "Single-user mode is intended as a system recovery\nmethod, providing a single user root access to the system by\nproviding a boot option at startup.\n

\nBy default, single-user mode is protected by requiring a password and is set\nin /usr/lib/systemd/system/rescue.service.", "rationale": "This prevents attackers with physical access from trivially bypassing security\non the machine and gaining root access. Such accesses are further prevented\nby configuring the bootloader password.", "severity": "medium", "references": {"cis-csc": ["1", "11", "12", "14", "15", "16", "18", "3", "5"], "cobit5": ["DSS05.02", "DSS05.04", "DSS05.05", "DSS05.07", "DSS05.10", "DSS06.03", "DSS06.06", "DSS06.10"], "cui": ["3.1.1", "3.4.5"], "hipaa": ["164.308(a)(1)(ii)(B)", "164.308(a)(7)(i)", "164.308(a)(7)(ii)(A)", "164.310(a)(1)", "164.310(a)(2)(i)", "164.310(a)(2)(ii)", "164.310(a)(2)(iii)", "164.310(b)", "164.310(c)", "164.310(d)(1)", "164.310(d)(2)(iii)"], "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"], "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"], "iso27001-2013": ["A.18.1.4", "A.6.1.2", "A.7.1.1", "A.9.1.2", "A.9.2.1", "A.9.2.2", "A.9.2.3", "A.9.2.4", "A.9.2.6", "A.9.3.1", "A.9.4.1", "A.9.4.2", "A.9.4.3", "A.9.4.4", "A.9.4.5"], "nerc-cip": ["CIP-003-8 R5.1.1", "CIP-003-8 R5.3", "CIP-004-6 R2.2.3", "CIP-004-6 R2.3", "CIP-007-3 R5.1", "CIP-007-3 R5.1.2", "CIP-007-3 R5.2", "CIP-007-3 R5.3.1", "CIP-007-3 R5.3.2", "CIP-007-3 R5.3.3"], "nist": ["IA-2", "AC-3", "CM-6(a)"], "nist-csf": ["PR.AC-1", "PR.AC-4", "PR.AC-6", "PR.AC-7", "PR.PT-3"], "ospp": ["FIA_UAU.1"], "srg": ["SRG-OS-000080-GPOS-00048"], "ism": ["0421", "0422", "0974", "1173", "1401", "1504", "1505", "1546", "1557", "1558", "1559", "1560", "1561"]}, "control_references": {"ism": ["0421", "0422", "0974", "1173", "1401", "1504", "1505", "1546", "1557", "1558", "1559", "1560", "1561"]}, "components": [], "identifiers": {}, "ocil_clause": "the output is different", "ocil": "To check if authentication is required for single-user mode, run the following command:\n
$ grep sulogin /usr/lib/systemd/system/rescue.service
\nThe output should be similar to the following, and the line must begin with\nExecStart and /sbin/sulogin.\n 
ExecStart=-/bin/sh -c \"/sbin/sulogin; /usr/bin/systemctl --fail --no-block default\"
\n\nIn case the output does not match, check if the ExecStart directive is not overridden:\n
grep ExecStart /etc/systemd/system/rescue.service.d/*.conf
\nThe output should contain two lines:\n
ExecStart=\nExecStart=-/bin/sh -c \"/sbin/sulogin; /usr/bin/systemctl --fail --no-block default\"
\n\n\n\nThen, verify that the rescue service is in the runlevel1.target.\nRun the following command:\n
$ sudo grep \"^Requires=.*rescue\\.service\" /usr/lib/systemd/system/runlevel1.target
\nThe output should be the following:\n
Requires=sysinit.target rescue.service
\n\nThen, check if there is no custom runlevel1 target configured in systemd configuration.\nRun the following command:\n
$ sudo grep -r \"^runlevel1.target$\" /etc/systemd/system
\nThere should be no output.\n\nThen, check if there is no custom rescue service configured in systemd configuration.\nRun the following command:\n
$ sudo grep -r \"^rescue.service$\" /etc/systemd/system
\nThere should be no output.", "oval_external_content": null, "fixtext": "Configure Ubuntu 22.04 to require authentication in single user mode.\n\nEnsure that there are following two lines in /etc/systemd/system/rescue.service.d/10-remediation.conf:\n
ExecStart=\nExecStart=-/bin/sh -c \"/sbin/sulogin; /usr/bin/systemctl --fail --no-block default\"
", "checktext": "", "vuldiscussion": "", "srg_requirement": "Ubuntu 22.04 must require authentication upon booting into rescue mode.", "warnings": [], "conflicts": [], "requires": [], "policy_specific_content": {"stig": {"srg_requirement": "Ubuntu 22.04 must require authentication to access single-user mode.", "vuldiscussion": "To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DOD-approved PKIs, all DOD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement.\n\nThis requirement prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.", "checktext": "Verify that Ubuntu 22.04 requires authentication for single-user mode with the following command:\n\n$ grep sulogin /usr/lib/systemd/system/rescue.service\n\nExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue\n\nIf this line is not returned, or is commented out, this is a finding.", "fixtext": "Configure Ubuntu 22.04 to require authentication for single-user mode.\n\nAdd or modify the following line in the \"/usr/lib/systemd/system/rescue.service\" file:\n\nExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue"}}, "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": "Require Authentication for Single User Mode", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/system/accounts/accounts-physical/require_singleuser_auth/rule.yml", "template": null}