Ubuntu 16.04 ESM / 18.04 ESM / 20.04 ESM : Tor vulnerabilities (USN-5036-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-5036-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(183153);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id(
    "CVE-2019-8955",
    "CVE-2021-28089",
    "CVE-2021-28090",
    "CVE-2021-34548",
    "CVE-2021-34549",
    "CVE-2021-34550",
    "CVE-2021-38385"
  );
  script_xref(name:"USN", value:"5036-1");

  script_name(english:"Ubuntu 16.04 ESM / 18.04 ESM / 20.04 ESM : Tor vulnerabilities (USN-5036-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 16.04 ESM / 18.04 ESM / 20.04 ESM host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-5036-1 advisory.

    It was discovered that Tor incorrectly handled certain memory operations. A remote attacker could use this
    issue to cause a denial of service. This issue only affected Ubuntu 18.04 ESM. (CVE-2019-8955)

    It was discovered that Tor did not properly handle the input length to dump_desc() function. A remote
    attacker could use this issue to cause a denial of service. This issue only affected Ubuntu 16.04 ESM,
    Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-28089)

    It was discovered that Tor did not properly sanitize the relay nickname in
    dirvote_add_signatures_to_pending_consensus() function. An attacker could possibly use this issue to cause
    an assertion failure and then cause a denial of service. (CVE-2021-28090)

    It was discovered that Tor did not properly validate the layer hint on half-open streams. A remote
    attacker could possibly use this issue to bypass the access control, leading to remote code execution.
    This issue only affected Ubuntu 20.04 ESM. (CVE-2021-34548)

    It was discovered that Tor was using an insecure hash function. A remote attacker could use this issue to
    cause a denial of service. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04
    ESM. (CVE-2021-34549)

    It was discovered that Tor did not properly manage memory under certain circumstances. If a user were
    tricked into opening a specially crafted request, a remote attacker could possibly use this issue to cause
    a crash, resulting in a denial of service, or possibly reading sensitive data. This issue only affected
    Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-34550)

    It was discovered that Tor mishandles the relationship between batch-signature verification and single-
    signature verification. An attacker could possibly use this issue to cause an assertion failure and then
    cause a denial of service. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04
    ESM. (CVE-2021-38385)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

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://ubuntu.com/security/notices/USN-5036-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected tor and / or tor-geoipdb packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/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:L/PR:N/UI:N/S:U/C:N/I:N/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-2021-38385");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/02/21");
  script_set_attribute(attribute:"patch_publication_date", value:"2022/10/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2023/10/16");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:esm");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:esm");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:esm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:tor");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:tor-geoipdb");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2023-2024 Canonical, Inc. / NASL script (C) 2023-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "ubuntu_pro_sub_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04 / 18.04 / 20.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);
var ubuntu_pro_detected = get_kb_item('Host/Ubuntu/Pro/Services/esm-apps');
ubuntu_pro_detected = !empty_or_null(ubuntu_pro_detected);

var pro_caveat_needed = FALSE;

var pkgs = [
    {'osver': '16.04', 'pkgname': 'tor', 'pkgver': '0.2.9.14-1ubuntu1~16.04.3+esm1', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'tor-geoipdb', 'pkgver': '0.2.9.14-1ubuntu1~16.04.3+esm1', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'tor', 'pkgver': '0.3.2.10-1ubuntu0.2~esm2', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'tor-geoipdb', 'pkgver': '0.3.2.10-1ubuntu0.2~esm2', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'tor', 'pkgver': '0.4.2.7-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'tor-geoipdb', 'pkgver': '0.4.2.7-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  var pro_required = NULL;
  if (!empty_or_null(package_array['ubuntu_pro'])) pro_required = package_array['ubuntu_pro'];
  if (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) {
        flag++;
        if (!ubuntu_pro_detected && !pro_caveat_needed) pro_caveat_needed = pro_required;
    }
  }
}

if (flag)
{
  var extra = '';
  if (pro_caveat_needed) {
    extra += 'NOTE: This vulnerability check contains fixes that apply to packages only \n';
    extra += 'available in Ubuntu ESM repositories. Access to these package security updates \n';
    extra += 'require an Ubuntu Pro subscription.\n\n';
  }
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'tor / tor-geoipdb');
}