Exim < 4.90.1 RCE Vulnerability - Version Check

# SPDX-FileCopyrightText: 2018 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:exim:exim";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.108367");
  script_version("2024-03-04T05:10:24+0000");
  script_tag(name:"last_modification", value:"2024-03-04 05:10:24 +0000 (Mon, 04 Mar 2024)");
  script_tag(name:"creation_date", value:"2018-03-08 08:12:01 +0100 (Thu, 08 Mar 2018)");
  script_tag(name:"cvss_base", value:"7.5");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_tag(name:"severity_vector", value:"CVSS:3.0/AV:N/AC:L/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:"2021-06-03 18:15:00 +0000 (Thu, 03 Jun 2021)");
  script_xref(name:"CISA", value:"Known Exploited Vulnerability (KEV) catalog");
  script_xref(name:"URL", value:"https://www.cisa.gov/known-exploited-vulnerabilities-catalog");
  script_cve_id("CVE-2018-6789");
  script_name("Exim < 4.90.1 RCE Vulnerability - Version Check");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2018 Greenbone AG");
  script_family("SMTP problems");
  script_dependencies("gb_exim_smtp_detect.nasl");
  script_mandatory_keys("exim/detected");

  script_xref(name:"URL", value:"https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/");
  script_xref(name:"URL", value:"https://exim.org/static/doc/security/CVE-2018-6789.txt");
  script_xref(name:"URL", value:"https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1");
  script_xref(name:"URL", value:"http://www.openwall.com/lists/oss-security/2018/02/07/2");

  script_tag(name:"summary", value:"Exim is prone to a remote code execution (RCE) vulnerability.");

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

  script_tag(name:"insight", value:"Exim is prone to an overflow vulnerability in the base64 decode
  function. The flaw exists due to a calculation mistake of decode buffer length in the b64decode
  function.");

  script_tag(name:"impact", value:"A remote attacker may execute arbitrary commands or conduct a
  denial of service attack.");

  script_tag(name:"affected", value:"Exim versions before 4.90.1.");

  script_tag(name:"solution", value:"Update to version 4.90.1 or later.");

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

  exit(0);
}

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

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

if( ! vers = get_app_version( cpe:CPE, port:port ) )
  exit( 0 );

if( version_is_less( version:vers, test_version:"4.90.1" ) ) {
  report = report_fixed_ver( installed_version:vers, fixed_version:"4.90.1" );
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );