Cisco Email Security Appliance AsyncOS TCP Flood Denial of Service Vulnerability

# SPDX-FileCopyrightText: 2015 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:/h:cisco:email_security_appliance";

if (description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.105437");
  script_cve_id("CVE-2015-6321");
  script_tag(name:"cvss_base", value:"7.8");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:C");
  script_version("2025-12-19T15:41:09+0000");

  script_name("Cisco Email Security Appliance AsyncOS TCP Flood Denial of Service Vulnerability");

  script_xref(name:"URL", value:"http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151104-aos");
  script_xref(name:"URL", value:"https://tools.cisco.com/bugsearch/bug/CSCus79774");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable version is present on the target host.");
  script_tag(name:"insight", value:"The vulnerability is due to improper handling of TCP packets sent at a high rate. An attacker could exploit this vulnerability by sending crafted TCP packets to the affected system.");
  script_tag(name:"solution", value:"See Vendor advisory.");
  script_tag(name:"summary", value:"A vulnerability in the network stack of Cisco AsyncOS for Email Security Appliance could allow an
unauthenticated, remote attacker to exhaust all available memory, preventing the affected device from accepting new TCP connections.");

  script_tag(name:"affected", value:"See Vendor advisory.");

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

  script_tag(name:"last_modification", value:"2025-12-19 15:41:09 +0000 (Fri, 19 Dec 2025)");
  script_tag(name:"creation_date", value:"2015-11-06 15:21:08 +0100 (Fri, 06 Nov 2015)");
  script_category(ACT_GATHER_INFO);
  script_family("CISCO");
  script_copyright("Copyright (C) 2015 Greenbone AG");
  script_dependencies("gb_cisco_esa_consolidation.nasl");
  script_mandatory_keys("cisco/esa/detected");

  exit(0);
}

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

if( ! version = get_app_version( cpe:CPE ) ) exit( 0 );

version = str_replace( string:version, find:"-", replace:"." );

if( version_is_less( version:version, test_version:'8.5.7.043' ) ) fix = '8.5.7-043';
if( version_in_range( version:version, test_version:'9.1', test_version2:'9.1.1.022' ) ) fix = '9.1.1-023';
if( version_in_range( version:version, test_version:'9.5', test_version2:'9.6.0.045' ) ) fix = '9.6.0-046';

if( fix )
{
  report = 'Installed version: ' + version + '\n' +
           'Fixed version:     ' + fix + '\n';

  security_message( port:0, data:report );
  exit( 0 );
}

exit( 99 );