AlmaLinux 8 : libssh (ALSA-2022:2031)

##
# (C) Tenable, Inc.
#
# The package checks in this plugin were extracted from
# AlmaLinux Security Advisory ALSA-2022:2031.
##

include('compat.inc');

if (description)
{
  script_id(161108);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/06");

  script_cve_id("CVE-2021-3634");
  script_xref(name:"ALSA", value:"2022:2031");
  script_xref(name:"IAVA", value:"2022-A-0041-S");

  script_name(english:"AlmaLinux 8 : libssh (ALSA-2022:2031)");

  script_set_attribute(attribute:"synopsis", value:
"The remote AlmaLinux host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The remote AlmaLinux 8 host has packages installed that are affected by a vulnerability as referenced in the
ALSA-2022:2031 advisory.

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared
    secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as
    an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked
    as long as these buffers were same. But the key re-exchange operation can also change the key exchange
    method, which can be based on hash of different size, eventually creating secret_hash of different size
    than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used
    again during second key re-exchange. (CVE-2021-3634)

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://errata.almalinux.org/8/ALSA-2022-2031.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:L/Au:S/C:N/I:N/A:P");
  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:L/UI:N/S:U/C:N/I:N/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-2021-3634");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/08/31");
  script_set_attribute(attribute:"patch_publication_date", value:"2022/05/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2022/05/12");

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

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

  script_copyright(english:"This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}


include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var release = get_kb_item('Host/AlmaLinux/release');
if (isnull(release) || 'AlmaLinux' >!< release) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_ver = pregmatch(pattern: "AlmaLinux release ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
var os_ver = os_ver[1];
if (! preg(pattern:"^8([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'AlmaLinux 8.x', 'AlmaLinux ' + os_ver);

if (!get_kb_item('Host/AlmaLinux/rpm-list')) 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, 'AlmaLinux', cpu);

var pkgs = [
    {'reference':'libssh-0.9.6-3.el8', 'cpu':'aarch64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libssh-0.9.6-3.el8', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libssh-config-0.9.6-3.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libssh-devel-0.9.6-3.el8', 'cpu':'aarch64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libssh-devel-0.9.6-3.el8', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var release = NULL;
  var sp = NULL;
  var cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) release = 'Alma-' + 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['exists_check'])) exists_check = package_array['exists_check'];
  if (reference && release && (!exists_check || rpm_exists(release:release, rpm:exists_check))) {
    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_WARNING,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libssh / libssh-config / libssh-devel');
}