Samba Man in the Middle Security Bypass Vulnerability (Heimdal)

# SPDX-FileCopyrightText: 2017 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:samba:samba";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.811522");
  script_version("2025-09-17T05:39:26+0000");
  script_cve_id("CVE-2017-11103");
  script_tag(name:"cvss_base", value:"6.8");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:P/I:P/A:P");
  script_tag(name:"last_modification", value:"2025-09-17 05:39:26 +0000 (Wed, 17 Sep 2025)");
  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:"2020-08-18 15:05:00 +0000 (Tue, 18 Aug 2020)");
  script_tag(name:"creation_date", value:"2017-07-13 12:28:31 +0530 (Thu, 13 Jul 2017)");
  script_name("Samba Man in the Middle Security Bypass Vulnerability (Heimdal)");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2017 Greenbone AG");
  script_family("General");
  script_dependencies("smb_nativelanman.nasl", "gb_samba_detect.nasl");
  script_mandatory_keys("samba/smb_or_ssh/detected");

  script_xref(name:"URL", value:"https://www.samba.org/samba/security/CVE-2017-11103.html");
  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/99551");

  script_tag(name:"summary", value:"Samba is prone to a MITM authentication validation bypass vulnerability.");

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

  script_tag(name:"insight", value:"The flaw is due to error in function
  '_krb5_extract_ticket' where the KDC-REP service name must be obtained from
  encrypted version stored in 'enc_part' instead of the unencrypted version
  stored in 'ticket'. Use of the unencrypted version provides an opportunity
  for successful server impersonation and other attacks.");

  script_tag(name:"impact", value:"Successfully exploiting this issue will allow
  a MITM attacker to impersonate a trusted server and thus gain elevated access
  to the domain by returning malicious replication or authorization data.");

  script_tag(name:"affected", value:"All versions of Samba from 4.0.0 before
  4.6.6 or 4.5.12 or 4.4.15.

  Note: All versions of Samba from 4.0.0 onwards using embedded Heimdal Kerberos.
  Samba binaries built against MIT Kerberos are not vulnerable.");

  script_tag(name:"solution", value:"Upgrade to Samba 4.6.6 or 4.5.12 or 4.4.15
  or later or apply the patch from below.");

  script_xref(name:"URL", value:"https://www.samba.org/samba/security");
  script_tag(name:"solution_type", value:"VendorFix");
  script_tag(name:"qod_type", value:"remote_banner_unreliable");

  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 );

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

if(vers =~ "^4\."){
  if(version_is_less(version:vers, test_version:"4.4.15")){
    fix = "4.4.15";
  }

  else if(vers =~ "^4\.5" && version_is_less(version:vers, test_version:"4.5.12")){
    fix = "4.5.12";
  }

  else if(vers =~ "^4\.6" && version_is_less(version:vers, test_version:"4.6.6")){
    fix = "4.6.6";
  }
}

if(fix){
  report = report_fixed_ver( installed_version:vers, fixed_version:fix, install_path:loc );
  security_message( data:report, port:port);
  exit(0);
}

exit(99);