Linux Distros Unpatched Vulnerability : CVE-2020-1938

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(245101);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/08/07");

  script_cve_id("CVE-2020-1938");
  script_xref(name:"CISA-KNOWN-EXPLOITED", value:"2022/03/17");
  script_xref(name:"CEA-ID", value:"CEA-2020-0021");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2020-1938");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to
    Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP
    connection. If such connections are available to an attacker, they can be exploited in ways that may be
    surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, Tomcat shipped
    with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected
    (and recommended in the security guide) that this Connector would be disabled if not required. This
    vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the
    web application - processing any file in the web application as a JSP Further, if the web application
    allowed file upload and stored those files within the web application (or the attacker was able to control
    the content of the web application by some other means) then this, along with the ability to process a
    file as a JSP, made remote code execution possible. It is important to note that mitigation is only
    required if an AJP port is accessible to untrusted users. Users wishing to take a defence-in-depth
    approach and block the vector that permits returning arbitrary files and execution as JSP may upgrade to
    Apache Tomcat 9.0.31, 8.5.51 or 7.0.100 or later. A number of changes were made to the default AJP
    Connector configuration in 9.0.31 to harden the default configuration. It is likely that users upgrading
    to 9.0.31, 8.5.51 or 7.0.100 or later will need to make small changes to their configurations.
    (CVE-2020-1938)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2020-1938");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:H/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:H/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-1938");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/02/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/08/07");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:tomcat7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:tomcat8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:tomcat9");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "libservlet3.0-java"},
          {"reference": "libservlet3.0-java-doc"},
          {"reference": "libtomcat7-java"},
          {"reference": "tomcat7"},
          {"reference": "tomcat7-admin"},
          {"reference": "tomcat7-common"},
          {"reference": "tomcat7-docs"},
          {"reference": "tomcat7-examples"},
          {"reference": "tomcat7-user"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "libservlet3.1-java"},
          {"reference": "libservlet3.1-java-doc"},
          {"reference": "libtomcat8-java"},
          {"reference": "tomcat7"},
          {"reference": "tomcat8"},
          {"reference": "tomcat8-admin"},
          {"reference": "tomcat8-common"},
          {"reference": "tomcat8-docs"},
          {"reference": "tomcat8-examples"},
          {"reference": "tomcat8-user"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "tomcat7"},
          {"reference": "tomcat8"},
          {"reference": "tomcat9"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');
var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}