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nessusThis script is Copyright (C) 2020-2023 and is owned by Tenable, Inc. or an Affiliate thereof.ORACLELINUX_ELSA-2020-4545.NASL
HistoryNov 12, 2020 - 12:00 a.m.

Oracle Linux 8 : libssh (ELSA-2020-4545)

2020-11-1200:00:00
This script is Copyright (C) 2020-2023 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
21

The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2020-4545 advisory.

  • A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES ciphers if enabled) ciphers. The server or client could crash when the connection hasn’t been fully initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat from this vulnerability is system availability. (CVE-2020-1730)

  • A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is executed on the server-side. In case the library is used in a way where users can influence the third parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading to a compromise of the remote target. (CVE-2019-14889)

Note that Nessus has not tested for this issue but has instead relied only on the application’s self-reported version number.

##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Oracle Linux Security Advisory ELSA-2020-4545.
##

include('compat.inc');

if (description)
{
  script_id(142768);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/02/02");

  script_cve_id("CVE-2019-14889", "CVE-2020-1730");

  script_name(english:"Oracle Linux 8 : libssh (ELSA-2020-4545)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Oracle Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the
ELSA-2020-4545 advisory.

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES
    ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully
    initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat
    from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is
    executed on the server-side. In case the library is used in a way where users can influence the third
    parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading
    to a compromise of the remote target. (CVE-2019-14889)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://linux.oracle.com/errata/ELSA-2020-4545.html");
  script_set_attribute(attribute:"solution", value:
"Update the affected libssh, libssh-config and / or libssh-devel packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-14889");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/12/10");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/11/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/11/12");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:oracle:linux:8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:libssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:libssh-config");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:libssh-devel");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2020-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/OracleLinux", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/local_checks_enabled");

  exit(0);
}


include('audit.inc');
include('global_settings.inc');
include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item('Host/OracleLinux')) audit(AUDIT_OS_NOT, 'Oracle Linux');
release = get_kb_item("Host/RedHat/release");
if (isnull(release) || !pregmatch(pattern: "Oracle (?:Linux Server|Enterprise Linux)", string:release)) audit(AUDIT_OS_NOT, 'Oracle Linux');
os_ver = pregmatch(pattern: "Oracle (?:Linux Server|Enterprise Linux) .*release ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Oracle Linux');
os_ver = os_ver[1];
if (! preg(pattern:"^8([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Oracle Linux 8', 'Oracle Linux ' + os_ver);

if (!get_kb_item('Host/RedHat/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Oracle Linux', cpu);

pkgs = [
    {'reference':'libssh-0.9.4-2.el8', 'cpu':'aarch64', 'release':'8'},
    {'reference':'libssh-0.9.4-2.el8', 'cpu':'i686', 'release':'8'},
    {'reference':'libssh-0.9.4-2.el8', 'cpu':'x86_64', 'release':'8'},
    {'reference':'libssh-config-0.9.4-2.el8', 'release':'8'},
    {'reference':'libssh-devel-0.9.4-2.el8', 'cpu':'aarch64', 'release':'8'},
    {'reference':'libssh-devel-0.9.4-2.el8', 'cpu':'i686', 'release':'8'},
    {'reference':'libssh-devel-0.9.4-2.el8', 'cpu':'x86_64', 'release':'8'}
];

flag = 0;
foreach package_array ( pkgs ) {
  reference = NULL;
  release = NULL;
  sp = NULL;
  cpu = NULL;
  el_string = NULL;
  rpm_spec_vers_cmp = NULL;
  epoch = NULL;
  allowmaj = NULL;
  rpm_prefix = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) release = 'EL' + package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['rpm_prefix'])) rpm_prefix = package_array['rpm_prefix'];
  if (reference && release) {
    if (rpm_prefix) {
        if (rpm_exists(release:release, rpm:rpm_prefix) && rpm_check(release:release, sp:sp, cpu:cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj)) flag++;
    } else {
        if (rpm_check(release:release, sp:sp, cpu:cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj)) flag++;
    }
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libssh / libssh-config / libssh-devel');
}