OpenBSD OpenSSH < 4.4p1, 8.5p1 - 9.7p1 RCE Vulnerability (regreSSHion)

# SPDX-FileCopyrightText: 2024 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

CPE = "cpe:/a:openbsd:openssh";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.114680");
  script_version("2024-07-09T05:05:54+0000");
  script_tag(name:"last_modification", value:"2024-07-09 05:05:54 +0000 (Tue, 09 Jul 2024)");
  script_tag(name:"creation_date", value:"2024-07-01 13:29:27 +0000 (Mon, 01 Jul 2024)");
  script_tag(name:"cvss_base", value:"7.6");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:H/Au:N/C:C/I:C/A:C");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2024-07-05 15:10:37 +0000 (Fri, 05 Jul 2024)");

  script_cve_id("CVE-2024-6387");

  script_tag(name:"qod_type", value:"remote_banner_unreliable");

  script_tag(name:"solution_type", value:"VendorFix");

  script_name("OpenBSD OpenSSH < 4.4p1, 8.5p1 - 9.7p1 RCE Vulnerability (regreSSHion)");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2024 Greenbone AG");
  script_family("General");
  script_dependencies("gb_openssh_consolidation.nasl");
  script_mandatory_keys("openssh/detected");

  script_tag(name:"summary", value:"OpenBSD OpenSSH is prone to a remote code execution (RCE)
  vulnerability dubbed 'regreSSHion'.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable version is present on the target host.");

  script_tag(name:"insight", value:"Vendor insights:

  1) Race condition in sshd(8)

  A critical vulnerability in sshd(8) was present that may allow arbitrary code execution with root
  privileges.

  Successful exploitation has been demonstrated on 32-bit Linux/glibc systems with ASLR. Under lab
  conditions, the attack requires on average 6-8 hours of continuous connections up to the maximum
  the server will accept. Exploitation on 64-bit systems is believed to be possible but has not been
  demonstrated at this time. It's likely that these attacks will be improved upon.

  Exploitation on non-glibc systems is conceivable but has not been examined. Systems that lack ASLR
  or users of downstream Linux distributions that have modified OpenSSH to disable per-connection
  ASLR re-randomisation (yes - this is a thing, no - we don't understand why) may potentially have
  an easier path to exploitation.

  OpenBSD is not vulnerable.");

  script_tag(name:"affected", value:"OpenBSD OpenSSH versions prior to 4.4p1 (unless patched for
  CVE-2006-5051 and CVE-2008-4109) and 8.5p1 through 9.7p1.");

  script_tag(name:"solution", value:"Update to version 9.8 or later.");

  script_xref(name:"URL", value:"https://www.openssh.com/txt/release-9.8");
  script_xref(name:"URL", value:"https://www.openssh.com/security.html");
  script_xref(name:"URL", value:"https://www.qualys.com/2024/07/01/cve-2024-6387/regresshion.txt");
  script_xref(name:"URL", value:"https://www.qualys.com/regresshion-cve-2024-6387/");
  script_xref(name:"URL", value:"https://blog.qualys.com/vulnerabilities-threat-research/2024/07/01/regresshion-remote-unauthenticated-code-execution-vulnerability-in-openssh-server");
  script_xref(name:"URL", value:"https://unit42.paloaltonetworks.com/threat-brief-cve-2024-6387-openssh/");

  exit(0);
}

include("version_func.inc");
include("host_details.inc");

if (isnull(port = get_app_port(cpe: CPE)))
  exit(0);

if (!infos = get_app_version_and_location(cpe: CPE, port: port, exit_no_version: TRUE))
  exit(0);

version = infos["version"];
location = infos["location"];

if (version_is_less(version: version, test_version: "4.4p1") ||
    version_in_range(version: version, test_version: "8.5p1", test_version2: "9.7p1")) {
  report = report_fixed_ver(installed_version: version, fixed_version: "9.8", install_path: location);
  security_message(port: port, data: report);
  exit(0);
}

exit(99);