{"description": "To set the runtime status of the <code>net.ipv6.conf.default.accept_source_route</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv6.conf.default.accept_source_route=0</pre>\nTo make sure that the setting is persistent, add the following line to a file in the directory <tt>/etc/sysctl.d</tt>: <pre>net.ipv6.conf.default.accept_source_route = 0</pre>", "rationale": "Source-routed packets allow the source of the packet to suggest routers\nforward the packet along a different path than configured on the router, which can\nbe used to bypass network security measures. This requirement applies only to the\nforwarding of source-routerd traffic, such as when IPv6 forwarding is enabled and\nthe system is functioning as a router.\n\nAccepting source-routed packets in the IPv6 protocol has few legitimate\nuses. It should be disabled unless it is absolutely required.", "severity": "medium", "references": {"cis-csc": ["1", "12", "13", "14", "15", "16", "18", "4", "6", "8", "9"], "cobit5": ["APO01.06", "APO13.01", "DSS01.05", "DSS03.01", "DSS05.02", "DSS05.04", "DSS05.07", "DSS06.02"], "cui": ["3.1.20"], "isa-62443-2009": ["4.2.3.4", "4.3.3.4", "4.4.3.3"], "isa-62443-2013": ["SR 3.1", "SR 3.5", "SR 3.8", "SR 4.1", "SR 4.3", "SR 5.1", "SR 5.2", "SR 5.3", "SR 7.1", "SR 7.6"], "iso27001-2013": ["A.10.1.1", "A.11.1.4", "A.11.1.5", "A.11.2.1", "A.12.1.1", "A.12.1.2", "A.13.1.1", "A.13.1.2", "A.13.1.3", "A.13.2.1", "A.13.2.2", "A.13.2.3", "A.13.2.4", "A.14.1.2", "A.14.1.3", "A.6.1.2", "A.7.1.1", "A.7.1.2", "A.7.3.1", "A.8.2.2", "A.8.2.3", "A.9.1.1", "A.9.1.2", "A.9.2.3", "A.9.4.1", "A.9.4.4", "A.9.4.5"], "nist": ["CM-7(a)", "CM-7(b)", "CM-6(a)", "CM-6(b)", "CM-6.1(iv)"], "nist-csf": ["DE.AE-1", "ID.AM-3", "PR.AC-5", "PR.DS-5", "PR.PT-4"], "pcidss": ["Req-1.4.3"], "srg": ["SRG-OS-000480-GPOS-00227"], "anssi": ["R13"], "cis": ["3.3.8"], "pcidss4": ["1.4.2", "1.4"]}, "control_references": {"anssi": ["R13"], "cis": ["3.3.8"], "pcidss4": ["1.4.2", "1.4"]}, "components": [], "identifiers": {}, "ocil_clause": "the correct value is not returned", "ocil": "The runtime status of the <code>net.ipv6.conf.default.accept_source_route</code> kernel parameter can be queried\nby running the following command:\n<pre>$ sysctl net.ipv6.conf.default.accept_source_route</pre>\n<code>0</code>.\n", "oval_external_content": null, "fixtext": "Configure Ubuntu 22.04 to not forward IPv6 source-routed packets by default.\nAdd or edit the following line in a system configuration file in the \"/etc/sysctl.d/\" directory:\nnet.ipv6.conf.default.accept_source_route = 0\n\nLoad settings from all system configuration files with the following command:\n\n$ sudo sysctl --system", "checktext": "", "vuldiscussion": "", "srg_requirement": "Ubuntu 22.04 must not forward IPv6 source-routed packets by default.", "warnings": [], "conflicts": [], "requires": [], "policy_specific_content": {"stig": {"srg_requirement": "Ubuntu 22.04 must not forward IPv6 source-routed packets by default.", "vuldiscussion": "Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when forwarding is enabled and the system is functioning as a router.\n\nAccepting source-routed packets in the IPv6 protocol has few legitimate uses. It must be disabled unless it is absolutely required.", "checktext": "Verify Ubuntu 22.04 does not accept IPv6 source-routed packets by default.\n\nNote: If IPv6 is disabled on the system, this requirement is Not Applicable.\n\nCheck the value of the accept source route variable with the following command:\n\n$ sudo sysctl net.ipv6.conf.default.accept_source_route\n\nnet.ipv6.conf.default.accept_source_route = 0\n\nIf the returned line does not have a value of \"0\", a line is not returned, or the line is commented out, this is a finding.\n\nCheck that the configuration files are present to enable this network parameter.\n\n$ sudo /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' |  grep -F net.ipv6.conf.default.accept_source_route | tail -1\n\nnet.ipv6.conf.default.accept_source_route = 0\n\nIf \"net.ipv6.conf.default.accept_source_route\" is not set to \"0\" or is missing, this is a finding.", "fixtext": "Configure Ubuntu 22.04 to not forward IPv6 source-routed packets by default.\n\nAdd or edit the following line in a single system configuration file, in the \"/etc/sysctl.d/\" directory:\n\nnet.ipv6.conf.default.accept_source_route = 0\n\nLoad settings from all system configuration files with the following command:\n\n$ sudo sysctl --system"}}, "platform": "system_with_kernel", "platforms": ["system_with_kernel"], "sce_metadata": {"check-import": "stdout", "check-export": ["sysctl_net_ipv6_conf_default_accept_source_route_value=xccdf_org.ssgproject.content_value_sysctl_net_ipv6_conf_default_accept_source_route_value"], "platform": ["multi_platform_all"], "environment": "any", "filename": "sysctl_net_ipv6_conf_default_accept_source_route.sh", "relative_path": "ubuntu2204/checks/sce/sysctl_net_ipv6_conf_default_accept_source_route.sh"}, "inherited_platforms": ["ipv6[enabled]"], "cpe_platform_names": ["system_with_kernel"], "inherited_cpe_platform_names": ["ipv6_enabled"], "bash_conditional": null, "fixes": {}, "title": "Disable Kernel Parameter for Accepting Source-Routed Packets on IPv6 Interfaces by Default", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/system/network/network-ipv6/configuring_ipv6/sysctl_net_ipv6_conf_default_accept_source_route/rule.yml", "template": {"name": "sysctl", "vars": {"sysctlvar": "net.ipv6.conf.default.accept_source_route", "datatype": "int"}, "backends": {}}}