Xen Hypervisor I/O Intercept Code Hypervisor Stack Guest-to-Host Information Disclosure (XSA-239)

#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(103974);
  script_version("1.7");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/06/03");

  script_cve_id(
    "CVE-2017-15588",
    "CVE-2017-15589",
    "CVE-2017-15590",
    "CVE-2017-15591",
    "CVE-2017-15592",
    "CVE-2017-15593",
    "CVE-2017-15594",
    "CVE-2017-15595",
    "CVE-2017-15596"
  );
  script_bugtraq_id(101490, 101496, 101500);
  script_xref(name:"IAVB", value:"2017-B-0142-S");

  script_name(english:"Xen Hypervisor I/O Intercept Code Hypervisor Stack Guest-to-Host Information Disclosure (XSA-239)");
  script_summary(english:"Checks 'xl info' output for the Xen hypervisor version.");

  script_set_attribute(attribute:"synopsis", value:
"The remote Xen hypervisor installation is missing a security update.");
  script_set_attribute(attribute:"description", value:
"According to its self-reported version number, the Xen hypervisor
installed on the remote host is affected by an unspecified flaw in the
hvmemul_do_io() function in arch/x86/hvm/emulate.c that is triggered
as an internal structure may contain data from an uninitialized
hypervisor stack slot. This may allow an attacker on the guest to gain
access to potentially sensitive information from the host.

Note that Nessus has checked the changeset versions based on the
xen.git change log. Nessus did not check guest hardware configurations
or if patches were applied manually to the source code before a
recompile and reinstall.");
  script_set_attribute(attribute:"see_also", value:"http://xenbits.xen.org/xsa/advisory-239.html");
  script_set_attribute(attribute:"see_also", value:"https://xenbits.xen.org/gitweb/?p=xen.git;a=summary");
  script_set_attribute(attribute:"solution", value:
"Apply the appropriate patch according to the vendor advisory.");
  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:C/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-2017-15595");

  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:"2017/10/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/10/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/10/19");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:xen:xen");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2017-2021 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("xen_server_detect.nbin");
  script_require_keys("installed_sw/Xen Hypervisor", "Settings/ParanoidReport");

  exit(0);
}

include("audit.inc");
include("global_settings.inc");
include("install_func.inc");
include("misc_func.inc");

app_name = "Xen Hypervisor";
install  = get_single_install(app_name:app_name);
if (report_paranoia < 2) audit(AUDIT_PARANOID);

version         = install['version'];
display_version = install['display_version'];
path            = install['path'];
managed_status  = install['Managed status'];
changeset       = install['Changeset'];

if (!empty_or_null(changeset))
  display_version += " (changeset " + changeset + ")";

# Installations that are vendor-managed are handled by OS-specific local package checks
if (managed_status == "managed")
  audit(AUDIT_INST_PATH_NOT_VULN, app_name, display_version, path);

# XSA-239
fixes['4.5']['fixed_ver']           = '4.5.5';
fixes['4.5']['fixed_ver_display']   = '4.5.5 (changeset 03b06d3)';
fixes['4.5']['affected_ver_regex']  = '^4\\.5\\.';
fixes['4.5']['affected_changesets'] = make_list("77666b6", "bbeb763",
  "5fdf16f", "0e9967d", "da4f24d", "b7582ac", "196371c", "7afc8ad",
  "72c107b", "5659aa5", "a224de6", "6442fa9", "db487a6", "709230f",
  "83724d9", "04b8c4c", "0b2ceae", "e3f0768", "d5a5231", "c5b0fe5",
  "136ff4e", "42c8ba5", "d38489d", "df59014", "3217129", "4964e86",
  "c079597", "6ec173b", "a373456", "0780e81", "e5ef76d", "25eaa86",
  "ae02360", "5597df9", "c5de05e", "773094e", "e39a248", "7b3712a",
  "be35327", "8825df1", "d7e3725", "6eb61e4", "b1fcfed", "5779d6a",
  "afdd77e", "c18367a", "7b7fd80", "b30e165", "62ef9b2", "8071724",
  "235b5d5", "a28b99d", "ff294fc", "bc01e2d", "da50922", "386cc94",
  "139960f", "ec3ddd6", "988929a", "1c48dff", "20d4248", "9610422",
  "cd76cd3", "455fd66", "b820c31", "ac3d8bc", "cde86fc", "1678521",
  "83cb2db", "43d06ef", "2b17bf4", "1a2bda5", "0bd7faf", "e3426e2",
  "37281bc", "27be856", "bdf3ef1", "cc325c0", "8e7b84d", "387b8ae",
  "34fbae7", "1530da2", "274a1f6", "b679cfa", "877b760", "cfe165d",
  "84e4e56", "e4ae4b0");

fixes['4.6']['fixed_ver']           = '4.6.6';
fixes['4.6']['fixed_ver_display']   = '4.6.6 (changeset e0353b4)';
fixes['4.6']['affected_ver_regex']  = '^4\\.6\\.';
fixes['4.6']['affected_changesets'] = make_list("76f1549", "9bac910",
  "c7a43e3", "913d4f8", "c5881c5", "b0239cd", "78fd0c3", "9079e0d",
  "1658a87", "22b6dfa", "a8cd231", "629eddd", "64c03bb", "b4660b4",
  "1ac8162", "747df3c", "5ae011e", "f974d32", "3300ad3", "d708b69");

fixes['4.7']['fixed_ver']           = '4.7.4';
fixes['4.7']['fixed_ver_display']   = '4.7.4-pre (changeset 6a6a339)';
fixes['4.7']['affected_ver_regex']  = '^4\\.7\\.';
fixes['4.7']['affected_changesets'] = make_list("e61be54", "e3f7a64",
  "957ad23", "b1ae705", "3add76f", "314a8fc", "d6aad63", "7c99633",
  "145c18d", "c3fa5cd", "487f8f9", "ffcfc40", "c7783d9", "3331050",
  "83966a3", "a67b223", "68dbba2", "2728470", "dea68ed", "9d12253",
  "73d7bc5", "b704b1a", "ca4ef7b", "ece330a", "3d63ebc", "30d50f8",
  "2dc3cdb", "5151257", "c9f3ca0", "e873251", "8aebf85", "c362cde",
  "fece08a");

fixes['4.8']['fixed_ver']           = '4.8.3';
fixes['4.8']['fixed_ver_display']   = '4.8.3-pre (changeset b1f3f1d)';
fixes['4.8']['affected_ver_regex']  = '^4\\.8\\.';
fixes['4.8']['affected_changesets'] = make_list("7251c06", "1960ca8",
  "866cfa1", "ddd6e41", "370cc9a", "39e3024", "9f092f5", "667f70e",
  "2116fec", "1a535c3", "ee3fc24", "d623d82", "dda458c", "c642b12",
  "80d7ef3", "ff4f60a", "36898eb", "4d7ccae", "e574046", "90dafa4",
  "c020cf2");

fixes['4.9']['fixed_ver']           = '4.9.1';
fixes['4.9']['fixed_ver_display']   = '4.9.1-pre (changeset d842630)';
fixes['4.9']['affected_ver_regex']  = '^4\\.9\\.';
fixes['4.9']['affected_changesets'] = make_list("ef61bcf", "44ceb19",
  "ae45442", "784afd9", "22032b2", "58da67f", "d1b64cc", "9cde7a8",
  "1cdcb36", "84c039e", "b244ac9", "612044a", "e8fd372", "a568e25",
  "8fef83e", "478e40c", "22ea731", "e7703a2", "91ded3b", "2cc3d32",
  "79775f5", "43cb0c4", "4821228", "d23bcc5", "308654c", "6fd84b3",
  "89b36cc", "a9ecd60", "798f6c9", "6508278", "5587d9a", "527fc5c",
  "5ff1de3", "692ed82", "9bf14bb", "c57b1f9", "6b147fd", "0e186e3",
  "afc5ebf", "266fc0e", "4698106", "f4f02f1", "0fada05", "ab4eb6c",
  "b29ecc7", "a11d14b", "107401e", "1b7834a");

fix = NULL;
foreach ver_branch (keys(fixes))
{
  if (version =~ fixes[ver_branch]['affected_ver_regex'])
  {
    ret = ver_compare(ver:version, fix:fixes[ver_branch]['fixed_ver']);
    if (ret < 0)
      fix = fixes[ver_branch]['fixed_ver_display'];
    else if (ret == 0)
    {
      if (empty_or_null(changeset))
        fix = fixes[ver_branch]['fixed_ver_display'];
      else
        foreach affected_changeset (fixes[ver_branch]['affected_changesets'])
          if (changeset == affected_changeset)
            fix = fixes[ver_branch]['fixed_ver_display'];
    }
  }
}

if (empty_or_null(fix))
  audit(AUDIT_INST_PATH_NOT_VULN, app_name, display_version, path);

items  = make_array("Installed version", display_version,
                    "Fixed version", fix,
                    "Path", path);
order  = make_list("Path", "Installed version", "Fixed version");
report = report_items_str(report_items:items, ordered_fields:order) + '\n';

security_report_v4(port:0, extra:report, severity:SECURITY_HOLE);