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ENT-13766: Fix sshd hardening being overridden by drop-in configs #2136

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Merged
larsewi merged 3 commits into from
Mar 10, 2026
Merged

ENT-13766: Fix sshd hardening being overridden by drop-in configs #2136

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636eb4d
Fix sshd hardening being overridden by drop-in configs
larsewi Mar 10, 2026
853c492
Verify that the directives are actually disabled after restarting sshd
larsewi Mar 10, 2026
a5e9663
Fixed bug in policy where service restart fails
larsewi Mar 10, 2026
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53 changes: 32 additions & 21 deletions ci/cfengine-build-host-setup.cf
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Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,17 @@ bundle agent cfengine_build_host_setup

vars:
"suse_users_and_groups" slist => { "daemon", "bin", "sys" };
"sshd_hardening_directives" slist => {
"PermitRootLogin",
"PasswordAuthentication",
"KbdInteractiveAuthentication",
"ChallengeResponseAuthentication",
};
"sshd_config_files" slist => findfiles("/etc/ssh/sshd_config", "/etc/ssh/sshd_config.d/*.conf");
debian|ubuntu::
"sshd_service_name" string => "ssh";
!(debian|ubuntu)::
"sshd_service_name" string => "sshd";

classes:
any::
Expand Down Expand Up @@ -278,29 +289,14 @@ findtime = 600",
classes => if_repaired("fail2ban_config_changed"),
comment => "Configure fail2ban to ban IPs after 5 failed SSH attempts within 10 minutes";

"/etc/ssh/sshd_config"
edit_line => comment_lines_matching("^PermitRootLogin\s+(?!no\s*$).*", "#"),
classes => if_repaired("sshd_hardened"),
comment => "Comment out insecure PermitRootLogin values";
"/etc/ssh/sshd_config"
edit_line => comment_lines_matching("^PasswordAuthentication\s+(?!no\s*$).*", "#"),
"$(sshd_config_files)"
edit_line => comment_lines_matching("^$(sshd_hardening_directives)\s+(?!no\s*$).*", "#"),
classes => if_repaired("sshd_hardened"),
comment => "Comment out insecure PasswordAuthentication value";
comment => "Comment out insecure SSH auth directives in sshd_config and drop-ins";
"/etc/ssh/sshd_config"
edit_line => comment_lines_matching("^KbdInteractiveAuthentication\s+(?!no\s*$).*", "#"),
edit_line => prepend_if_no_line("$(sshd_hardening_directives) no"),
classes => if_repaired("sshd_hardened"),
comment => "Comment out insecure KbdInteractiveAuthentication value (OpenSSH 8.7+)";
"/etc/ssh/sshd_config"
edit_line => comment_lines_matching("^ChallengeResponseAuthentication\s+(?!no\s*$).*", "#"),
classes => if_repaired("sshd_hardened"),
comment => "Comment out insecure ChallengeResponseAuthentication value (OpenSSH < 8.7)";
"/etc/ssh/sshd_config"
edit_line => lines_present("PermitRootLogin no
PasswordAuthentication no
KbdInteractiveAuthentication no
ChallengeResponseAuthentication no"),
classes => if_repaired("sshd_hardened"),
comment => "Ensure SSH hardening directives are present";
comment => "Ensure SSH hardening directives are at the top of sshd_config, before any Include";

ubuntu_16|ubuntu_18|redhat_9|redhat_10::
"/etc/hosts" -> { "ENT-12437" }
Expand Down Expand Up @@ -383,10 +379,25 @@ jenkins_builds ALL=NOPASSWD: /usr/bin/podman
!have_sys_user.(suse|sles|opensuse)::
"useradd -u 3 sys" contain => in_shell;

linux::
"sshd -T 2>/dev/null | grep -qiE '^PermitRootLogin no'"
depends_on => { "sshd_restarted" },
contain => in_shell,
comment => "Verify PermitRootLogin is disabled";
"sshd -T 2>/dev/null | grep -qiE '^PasswordAuthentication no'"
depends_on => { "sshd_restarted" },
contain => in_shell,
comment => "Verify PasswordAuthentication is disabled";
"sshd -T 2>/dev/null | grep -qiE '^(KbdInteractive|ChallengeResponse)Authentication no'"
depends_on => { "sshd_restarted" },
contain => in_shell,
comment => "Verify KbdInteractiveAuthentication (OpenSSH 8.7+) or ChallengeResponseAuthentication (older) is disabled";

services:
sshd_hardened::
"sshd"
"$(sshd_service_name)"
service_policy => "restart",
handle => "sshd_restarted",
comment => "Restart sshd to apply hardened configuration";
any::
"fail2ban"
Expand Down