RHEL 6 : libvncserver (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 libvncserver. The text
# itself is copyright (C) Red Hat, Inc.
##

include('compat.inc');

if (description)
{
  script_id(196364);
  script_version("1.0");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/05/11");

  script_cve_id(
    "CVE-2016-9941",
    "CVE-2016-9942",
    "CVE-2018-7225",
    "CVE-2018-15127",
    "CVE-2018-20019",
    "CVE-2018-20020",
    "CVE-2018-20022",
    "CVE-2018-20024",
    "CVE-2018-20748",
    "CVE-2018-20749",
    "CVE-2018-20750",
    "CVE-2019-15681",
    "CVE-2019-15690",
    "CVE-2020-14397",
    "CVE-2020-14398",
    "CVE-2020-14401",
    "CVE-2020-14402",
    "CVE-2020-14403",
    "CVE-2020-14404",
    "CVE-2020-14405",
    "CVE-2020-25708"
  );

  script_name(english:"RHEL 6 : libvncserver (Unpatched Vulnerability)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat 6 host is affected by multiple vulnerabilities that will not be patched.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 6 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.

  - libvncserver: Improper input sanitization in rfbProcessClientNormalMessage in rfbserver.c (CVE-2018-7225)

  - Heap-based buffer overflow in rfbproto.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote
    servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted
    FramebufferUpdate message containing a subrectangle outside of the client drawing area. (CVE-2016-9941)

  - Heap-based buffer overflow in ultra.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote servers
    to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted
    FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeds
    what is specified by the tile dimensions. (CVE-2016-9942)

  - LibVNC before commit 502821828ed00b4a2c4bef90683d0fd88ce495de contains heap out-of-bound write
    vulnerability in server code of file transfer extension that can result remote code execution
    (CVE-2018-15127)

  - LibVNC before commit a83439b9fbe0f03c48eb94ed05729cb016f8b72f contains multiple heap out-of-bound write
    vulnerabilities in VNC client code that can result remote code execution (CVE-2018-20019)

  - LibVNC before commit 7b1ef0ffc4815cab9a96c7278394152bdc89dc4d contains heap out-of-bound write
    vulnerability inside structure in VNC client code that can result remote code execution (CVE-2018-20020)

  - LibVNC before 2f5b2ad1c6c99b1ac6482c95844a84d66bb52838 contains multiple weaknesses CWE-665: Improper
    Initialization vulnerability in VNC client code that allows attacker to read stack memory and can be abuse
    for information disclosure. Combined with another vulnerability, it can be used to leak stack memory
    layout and in bypassing ASLR (CVE-2018-20022)

  - LibVNC before commit 4a21bbd097ef7c44bb000c3bd0907f96a10e4ce7 contains null pointer dereference in VNC
    client code that can result DoS. (CVE-2018-20024)

  - LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in
    libvncclient/rfbproto.c. The fix for CVE-2018-20019 was incomplete. (CVE-2018-20748)

  - LibVNC before 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The
    fix for CVE-2018-15127 was incomplete. (CVE-2018-20749)

  - LibVNC through 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The
    fix for CVE-2018-15127 was incomplete. (CVE-2018-20750)

  - LibVNC commit before d01e1bb4246323ba6fcee3b82ef1faa9b1dac82a contains a memory leak (CWE-655) in VNC
    server code, which allow an attacker to read stack memory and can be abused for information disclosure.
    Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR. This attack
    appear to be exploitable via network connectivity. These vulnerabilities have been fixed in commit
    d01e1bb4246323ba6fcee3b82ef1faa9b1dac82a. (CVE-2019-15681)

  - libvncserver: HandleCursorShape() integer overflow resulting in heap-based buffer overflow
    (CVE-2019-15690)

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/rfbregion.c has a NULL pointer
    dereference. (CVE-2020-14397)

  - An issue was discovered in LibVNCServer before 0.9.13. An improperly closed TCP connection causes an
    infinite loop in libvncclient/sockets.c. (CVE-2020-14398)

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/scale.c has a pixel_value integer
    overflow. (CVE-2020-14401)

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/corre.c allows out-of-bounds access
    via encodings. (CVE-2020-14402)

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/hextile.c allows out-of-bounds access
    via encodings. (CVE-2020-14403)

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/rre.c allows out-of-bounds access via
    encodings. (CVE-2020-14404)

  - An issue was discovered in LibVNCServer before 0.9.13. libvncclient/rfbproto.c does not limit TextChat
    size. (CVE-2020-14405)

  - A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw
    to send a specially crafted message that, when processed by the VNC server, would lead to a floating point
    exception, resulting in a denial of service. (CVE-2020-25708)

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:N/AC:L/Au:N/C:P/I:P/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: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-2018-7225");

  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:"2016/12/31");
  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:6");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:libvncserver");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:vino");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  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: '6')) audit(AUDIT_OS_NOT, 'Red Hat 6.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':'libvncserver', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'unpatched_pkg':'libvncserver'},
      {'reference':'vino', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'unpatched_pkg':'vino', 'cves':['CVE-2019-15681', 'CVE-2020-14397', 'CVE-2020-14402', 'CVE-2020-14403', 'CVE-2020-14404', 'CVE-2020-25708']}
    ]
  }
];


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, 'libvncserver / vino');
}