PQC Key Exchange (KEX) Algorithm(s) Missing (SSH)

# SPDX-FileCopyrightText: 2025 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.119214");
  script_version("2026-06-23T06:54:08+0000");
  script_tag(name:"last_modification", value:"2026-06-23 06:54:08 +0000 (Tue, 23 Jun 2026)");
  script_tag(name:"creation_date", value:"2025-10-29 11:56:43 +0000 (Wed, 29 Oct 2025)");
  script_tag(name:"cvss_base", value:"0.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:N");
  script_name("PQC Key Exchange (KEX) Algorithm(s) Missing (SSH)");
  script_copyright("Copyright (C) 2025 Greenbone AG");
  script_category(ACT_GATHER_INFO);
  script_family("SSL and TLS");
  script_dependencies("gb_ssh_algos.nasl");
  script_require_ports("Services/ssh", 22);
  script_mandatory_keys("ssh/pqc_algos_missing");

  script_xref(name:"URL", value:"https://openssh.com/pq.html");
  script_xref(name:"URL", value:"https://quantumcomputingreport.com/openssh-10-0-introduces-default-post-quantum-key-exchange-algorithm/");
  script_xref(name:"URL", value:"https://www.nist.gov/news-events/news/2024/08/nist-releases-first-3-finalized-post-quantum-encryption-standards");
  script_xref(name:"URL", value:"https://csrc.nist.gov/News/2024/postquantum-cryptography-fips-approved");
  script_xref(name:"URL", value:"https://www.forescout.com/blog/post-quantum-cryptography-the-real-risks-of-not-adopting-it/");
  script_xref(name:"URL", value:"https://datatracker.ietf.org/doc/draft-ietf-sshm-mlkem-hybrid-kex/");
  script_xref(name:"URL", value:"https://datatracker.ietf.org/doc/rfc9941/");
  script_xref(name:"URL", value:"https://supportportal.juniper.net/s/article/2026-03-Reference-Advisory-OpenSSH-client-new-warning-in-versions-10-1-and-higher-connection-is-not-using-a-post-quantum-key-exchange-algorithm");

  script_tag(name:"summary", value:"The remote SSH server is configured to NOT allow / support at
  least ONE Post-Quantum Cryptography (PQC) key exchange (KEX) algorithm(s).");

  # nb: When adding more algorithms here please make sure to also adjust / extend the following
  # accordingly:
  # - 2025/gb_ssh_pqc_kex_algo_supported.nasl
  # - gb_ssh_algos.nasl
  script_tag(name:"vuldetect", value:"Checks the (previously collected) supported KEX algorithms of
  the remote SSH server.

  Currently the following PQC KEX algorithms are defined / getting used for this check:

  - [email protected]

  - sntrup761x25519-sha512

  - mlkem768x25519-sha256

  - [email protected]

  - [email protected]

  - [email protected]

  - [email protected]

  - [email protected]

  - mlkem1024nistp384-sha384

  - mlkem768nistp256-sha256

  - [email protected]

  - [email protected]");

  script_tag(name:"impact", value:"The connection may be vulnerable to 'store now, decrypt later'
  attacks.");

  script_tag(name:"solution", value:"Update the remote SSH server to a version supporting PQC KEX
  algorithms (e.g. OpenSSH 8.9 or later) and enable relevant PQC KEX algorithms accordingly.

  Please see the references/manual of the remote SSH server and/or contact the vendor of it for more
  support.");

  script_tag(name:"solution_type", value:"Mitigation");
  script_tag(name:"qod_type", value:"remote_banner");

  exit(0);
}

include("ssh_func.inc");
include("port_service_func.inc");
include("host_details.inc");

port = ssh_get_port( default:22 );

if( ! get_kb_item( "ssh/" + port + "/pqc_algos_missing" ) )
  exit( 0 );

# nb:
# - Store the reference from this one to gb_ssh_algos.nasl to show a cross-reference within the
#   reports
# - We don't want to use get_app_* functions as we're only interested in the cross-reference here
register_host_detail( name:"detected_by", value:"1.3.6.1.4.1.25623.1.0.105565" ); # gb_ssh_algos.nasl
register_host_detail( name:"detected_at", value:port + "/tcp" );

log_message( port:port, data:"The remote SSH server is NOT supporting at least ONE PQC KEX algorithm." );
exit( 0 );