Apache 2.4.x < 2.4.25 Multiple Vulnerabilities (httpoxy)

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(96451);
  script_version("1.18");
  script_set_attribute(attribute:"plugin_modification_date", value:"2022/04/11");

  script_cve_id(
    "CVE-2016-0736",
    "CVE-2016-2161",
    "CVE-2016-4975",
    "CVE-2016-5387",
    "CVE-2016-8740",
    "CVE-2016-8743",
    "CVE-2020-11985"
  );
  script_bugtraq_id(
    91816,
    94650,
    95076,
    95077,
    95078,
    105093
  );
  script_xref(name:"CERT", value:"797896");
  script_xref(name:"EDB-ID", value:"40961");

  script_name(english:"Apache 2.4.x < 2.4.25 Multiple Vulnerabilities (httpoxy)");

  script_set_attribute(attribute:"synopsis", value:
"The remote web server is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"According to its banner, the version of Apache running on the remote
host is 2.4.x prior to 2.4.25. It is, therefore, affected by the
following vulnerabilities :

  - A flaw exists in the mod_session_crypto module due to
    encryption for data and cookies using the configured
    ciphers with possibly either CBC or ECB modes of
    operation (AES256-CBC by default). An unauthenticated,
    remote attacker can exploit this, via a padding oracle
    attack, to decrypt information without knowledge of the
    encryption key, resulting in the disclosure of
    potentially sensitive information. (CVE-2016-0736)

  - A denial of service vulnerability exists in the
    mod_auth_digest module during client entry allocation.
    An unauthenticated, remote attacker can exploit this,
    via specially crafted input, to exhaust shared memory
    resources, resulting in a server crash. (CVE-2016-2161)

  - The Apache HTTP Server is affected by a
    man-in-the-middle vulnerability known as 'httpoxy' due
    to a failure to properly resolve namespace conflicts in
    accordance with RFC 3875 section 4.1.18. The HTTP_PROXY
    environment variable is set based on untrusted user data
    in the 'Proxy' header of HTTP requests. The HTTP_PROXY
    environment variable is used by some web client
    libraries to specify a remote proxy server. An
    unauthenticated, remote attacker can exploit this, via a
    crafted 'Proxy' header in an HTTP request, to redirect
    an application's internal HTTP traffic to an arbitrary
    proxy server where it may be observed or manipulated.
    (CVE-2016-5387)

  - A denial of service vulnerability exists in the
    mod_http2 module due to improper handling of the
    LimitRequestFields directive. An unauthenticated, remote
    attacker can exploit this, via specially crafted
    CONTINUATION frames in an HTTP/2 request, to inject
    unlimited request headers into the server, resulting in
    the exhaustion of memory resources. (CVE-2016-8740)

  - A flaw exists due to improper handling of whitespace
    patterns in user-agent headers. An unauthenticated,
    remote attacker can exploit this, via a specially
    crafted user-agent header, to cause the program to
    incorrectly process sequences of requests, resulting in
    interpreting responses incorrectly, polluting the cache,
    or disclosing the content from one request to a second
    downstream user-agent. (CVE-2016-8743)

  - A CRLF injection allowing HTTP response splitting attacks for 
    sites which use mod_userdir (CVE-2016-4975)

Note that Nessus has not tested for these issues but has instead
relied only on the application's self-reported version number.");
  script_set_attribute(attribute:"see_also", value:"https://httpd.apache.org/dev/dist/Announcement2.4.html");
  script_set_attribute(attribute:"see_also", value:"http://httpd.apache.org/security/vulnerabilities_24.html");
  script_set_attribute(attribute:"see_also", value:"https://github.com/apache/httpd/blob/2.4.x/CHANGES");
  script_set_attribute(attribute:"see_also", value:"https://www.apache.org/security/asf-httpoxy-response.txt");
  script_set_attribute(attribute:"see_also", value:"https://httpoxy.org");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Apache version 2.4.25 or later.

Note that the 'httpoxy' vulnerability can be mitigated by applying the
workarounds or patches as referenced in the vendor advisory
asf-httpoxy-response.txt. Furthermore, to mitigate the other
vulnerabilities, ensure that the affected modules (mod_session_crypto,
mod_auth_digest, and mod_http2) are not in use.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2016-5387");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"in_the_news", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/07/18");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/12/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/01/12");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:apache:http_server");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Web Servers");

  script_copyright(english:"This script is Copyright (C) 2018-2022 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("apache_http_version.nasl", "apache_http_server_nix_installed.nbin", "apache_httpd_win_installed.nbin");
  script_require_keys("installed_sw/Apache");

  exit(0);
}

include('vcf.inc');
include('vcf_extras.inc');


app_info = vcf::apache_http_server::combined_get_app_info(app:'Apache');

constraints = [
  { "min_version":"2.3.0", "fixed_version":"2.4.25" }
];

vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_WARNING);