RHEL 5 : sudo (Unpatched Vulnerability)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory sudo. The text
# itself is copyright (C) Red Hat, Inc.
##

include('compat.inc');

if (description)
{
  script_id(195537);
  script_version("1.0");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/05/11");

  script_cve_id(
    "CVE-2016-7032",
    "CVE-2016-7076",
    "CVE-2016-7091",
    "CVE-2019-19232",
    "CVE-2019-19234",
    "CVE-2021-23239",
    "CVE-2021-23240"
  );
  script_xref(name:"IAVA", value:"2021-A-0053");

  script_name(english:"RHEL 5 : sudo (Unpatched Vulnerability)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat 5 host is affected by multiple vulnerabilities that will not be patched.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 5 host has one or more packages installed that are affected by multiple
vulnerabilities that have been acknowledged by the vendor but will not be patched.

  - sudo: noexec bypass via wordexp() (CVE-2016-7076)

  - sudo: symbolic link attack in SELinux-enabled sudoedit (CVE-2021-23240)

  - sudo_noexec.so in Sudo before 1.8.15 on Linux might allow local users to bypass intended noexec command
    restrictions via an application that calls the (1) system or (2) popen function. (CVE-2016-7032)

  - sudo: It was discovered that the default sudo configuration on Red Hat Enterprise Linux and possibly other
    Linux implementations preserves the value of INPUTRC which could lead to information disclosure. A local
    user with sudo access to a restricted program that uses readline could use this flaw to read content from
    specially formatted files with elevated privileges provided by sudo. (CVE-2016-7091)

  - In Sudo through 1.8.29, an attacker with access to a Runas ALL sudoer account can impersonate a
    nonexistent user by invoking sudo with a numeric uid that is not associated with any user. NOTE: The
    software maintainer believes that this is not a vulnerability because running a command via sudo as a user
    not present in the local password database is an intentional feature. Because this behavior surprised some
    users, sudo 1.8.30 introduced an option to enable/disable this behavior with the default being disabled.
    However, this does not change the fact that sudo was behaving as intended, and as documented, in earlier
    versions (CVE-2019-19232)

  - In Sudo through 1.8.29, the fact that a user has been blocked (e.g., by using the ! character in the
    shadow file instead of a password hash) is not considered, allowing an attacker (who has access to a Runas
    ALL sudoer account) to impersonate any blocked user. NOTE: The software maintainer believes that this CVE
    is not valid. Disabling local password authentication for a user is not the same as disabling all access
    to that user--the user may still be able to login via other means (ssh key, kerberos, etc). Both the Linux
    shadow(5) and passwd(1) manuals are clear on this. Indeed it is a valid use case to have local accounts
    that are _only_ accessible via sudo and that cannot be logged into with a password. Sudo 1.8.30 added an
    optional setting to check the _shell_ of the target user (not the encrypted password!) against the
    contents of /etc/shells but that is not the same thing as preventing access to users with an invalid
    password hash (CVE-2019-19234)

  - The sudoedit personality of Sudo before 1.9.5 may allow a local unprivileged user to perform arbitrary
    directory-existence tests by winning a sudo_edit.c race condition in replacing a user-controlled directory
    by a symlink to an arbitrary path. (CVE-2021-23239)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package
is installed.");
  script_set_attribute(attribute:"solution", value:
"The vendor has acknowledged the vulnerabilities but no solution has been provided. Refer to the vendor for remediation
guidance.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/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-2016-7076");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2021-23240");

  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:"2016/08/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2024/05/11");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:5");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:6");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:compat-readline43");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:compat-readline5");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:readline");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:sudo");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}


include('rpm.inc');
include('rhel.inc');

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);
var os_release = get_kb_item('Host/RedHat/release');
if (isnull(os_release) || 'Red Hat' >!< os_release) audit(AUDIT_OS_NOT, 'Red Hat');
var os_ver = pregmatch(pattern: "Red Hat Enterprise Linux.*release ([0-9]+(\.[0-9]+)?)", string:os_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
os_ver = os_ver[1];
if (!rhel_check_release(operator: 'ge', os_version: os_ver, rhel_version: '5')) audit(AUDIT_OS_NOT, 'Red Hat 5.x', 'Red Hat ' + os_ver);

if (!get_kb_item('Host/RedHat/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 && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Red Hat', cpu);

var constraints = [
  {
    'pkgs': [
      {'reference':'compat-readline43', 'release':'5', 'rpm_spec_vers_cmp':TRUE, 'unpatched_pkg':'compat-readline43', 'cves':['CVE-2016-7091']},
      {'reference':'readline', 'release':'5', 'rpm_spec_vers_cmp':TRUE, 'unpatched_pkg':'readline', 'cves':['CVE-2016-7091']},
      {'reference':'sudo', 'release':'5', 'rpm_spec_vers_cmp':TRUE, 'unpatched_pkg':'sudo'}
    ]
  }
];


var flag = 0;
foreach var constraint_array ( constraints ) {
  var repo_relative_urls = NULL;
  var enterprise_linux_flag = rhel_repo_urls_has_content_dist_rhel(repo_urls:repo_relative_urls);
  foreach var pkg ( constraint_array['pkgs'] ) {
    var unpatched_pkg = NULL;
    var _release = NULL;
    var sp = NULL;
    var el_string = NULL;
    var rpm_spec_vers_cmp = NULL;
    var exists_check = NULL;
    var cves = NULL;
    if (!empty_or_null(pkg['unpatched_pkg'])) unpatched_pkg = pkg['unpatched_pkg'];
    if (!empty_or_null(pkg['release'])) _release = 'RHEL' + pkg['release'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (unpatched_pkg &&
        _release &&
        (!exists_check || rpm_exists(release:_release, rpm:exists_check)) &&
        unpatched_package_exists(release:_release, package:unpatched_pkg, cves: cves)) flag++;
  }
}

if (flag)
{
  var extra = NULL;
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : unpatched_packages_report()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'compat-readline43 / readline / sudo');
}