Xen Function Page Use Shadow Mode Reference Counting Improper Overflow Check Guest-to-Host DoS (XSA-249)

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

include("compat.inc");

if (description)
{
  script_id(105491);
  script_version("1.7");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/06/03");

  script_cve_id("CVE-2017-17563");
  script_xref(name:"IAVB", value:"2018-B-0007-S");

  script_name(english:"Xen Function Page Use Shadow Mode Reference Counting Improper Overflow Check Guest-to-Host DoS (XSA-249)");
  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 a guest-to-host denial
of service vulnerability.

Note that x86 systems are vulnerable. ARM systems are not vulnerable.

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-249.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: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:L/AC:H/PR:L/UI:N/S:C/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-2017-17563");

  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:"2017/12/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/12/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/12/29");

  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);

fixes['4.5']['fixed_ver']           = '4.5.5';
fixes['4.5']['fixed_ver_display']   = '4.5.5 (changeset c8fad5e)';
fixes['4.5']['affected_ver_regex']  = '^4\\.5\\.';
fixes['4.5']['affected_changesets'] = make_list("ab5ca36", "94a81c5",
  "ea1620f", "ca708d3", "d144bda", "41f6dd0", "b0be3c2", "42ea1dc",
  "08aa260", "03b06d3", "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 1ca93b7)';
fixes['4.6']['affected_ver_regex']  = '^4\\.6\\.';
fixes['4.6']['affected_changesets'] = make_list("8c0c36e", "6e43623",
  "47d3e73", "ea80245", "37bb22b", "9b0c2a2", "8d3fe28", "be63d66",
  "9454e30", "aad5a67", "d8b0ebf", "f0208a4", "42b2c82", "57318e1",
  "9f22d72", "e0353b4", "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']           = '4.7.5';
fixes['4.7']['fixed_ver_display']   = '4.7.5-pre (changeset 5a99156)';
fixes['4.7']['affected_ver_regex']  = '^4\\.7\\.';
fixes['4.7']['affected_changesets'] = make_list("4f34d9f", "4133de7",
  "b3981ea", "184f259", "67966a9", "af3f585");

fixes['4.8']['fixed_ver']           = '4.8.3';
fixes['4.8']['fixed_ver_display']   = '4.8.3-pre (changeset 5069fdd)';
fixes['4.8']['affected_ver_regex']  = '^4\\.8\\.';
fixes['4.8']['affected_changesets'] = make_list("a66b814", "d60d469",
  "e54bc7e", "fcc60bc", "60e86f3", "9ba6783", "bc244b7", "13eb73f",
  "6183d53", "1ac3ab7", "e1fa1c6", "96e76d8", "651d839", "14826e3",
  "814e065", "03af24c", "4a3c5e1", "2956a3f", "3cd9d84", "ffb2947",
  "f457a22", "011a612", "5b37b5c", "379213c", "f3b2080", "fcbbd0f",
  "0c647de", "bdc2ae6", "96e6364", "1a8ad09", "df89197", "c4f969d",
  "b1f3f1d", "7251c06", "1960ca8", "866cfa1", "ddd6e41", "370cc9a",
  "39e3024", "9f092f5", "667f70e", "2116fec", "1a535c3", "ee3fc24",
  "d623d82", "dda458c", "c642b12", "80d7ef3", "ff4f60a", "36898eb",
  "4d7ccae", "e574046", "90dafa4", "c020cf2");

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_WARNING);