Xen Project Insufficient TLB Flushing Vulnerability (XSA-275)

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

include("compat.inc");

if (description)
{
  script_id(119656);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/06/03");

  script_cve_id("CVE-2018-19961", "CVE-2018-19962");
  script_bugtraq_id(106182);
  script_xref(name:"IAVB", value:"2018-B-0149-S");

  script_name(english:"Xen Project Insufficient TLB Flushing Vulnerability (XSA-275)");
  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 vulnerability allowing
a guest system to potentially elevate privileges, access protected
information, and perform a DoS against the host. Only AMD systems with
IOMMU enabled are affected.

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:"https://xenbits.xen.org/xsa/advisory-275.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-2018-19962");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/11/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2018/11/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/12/13");

  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) 2018-2021 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['4.7']['fixed_ver']           = '4.7.6';
fixes['4.7']['fixed_ver_display']   = '4.7.6 (changeset 2b3463f)';
fixes['4.7']['affected_ver_regex']  = '^4\\.7\\.';
fixes['4.7']['affected_changesets'] = make_list("efe21ad", "9c82759",
  "3d3e474", "4e69e43", "3d33cc6", "3f7b4ec", "7ba1c7d", "87d5aa4",
  "9b8375a", "da93914", "0aa4696", "f05a33e", "f440b31", "1a90803",
  "0abc1ae", "1fdb25a", "c9641d4", "61c4360", "df66c1c", "59732fd",
  "3f7fd2b", "bcbd8b9", "dfee811", "95ff4e1", "ded2a37", "87dba80",
  "fe028e6", "a51e6a3", "0e66281", "51d9780", "91ca84c", "bce2dd6",
  "fa807e2", "97aff08", "e90e243", "c0e854b", "9858a1f", "a404136",
  "dc111e9", "0873699", "280a556");

fixes['4.8']['fixed_ver']           = '4.8.5';
fixes['4.8']['fixed_ver_display']   = '4.8.5-pre (changeset 14854d0)';
fixes['4.8']['affected_ver_regex']  = '^4\\.8\\.';
fixes['4.8']['affected_changesets'] = make_list("f030ad0", "d6798ce",
  "d792e57", "ba4eb85", "88b5e36", "64fd42f", "86cba9b", "49f74ea",
  "5b6fb33", "8d1afd1", "0dbe6ac", "38a7dde", "bd89569", "dee5937",
  "5670039", "53dfcb0", "d4f07fb", "005df91", "8bfab2b", "dc814e1",
  "5e86977", "d1a5936", "c9fc6b3", "21ac6c8", "e52ec4b", "d95b5bb",
  "565de91", "1c6c2de", "1f56fba", "5464d5f", "9e7d5e2", "7849d13",
  "e819108", "fe78829", "28fc483", "712082d", "ed6fcdb", "0406164",
  "e3d0ce3", "c00fabc", "3478439", "b81b74a", "b289403", "47fbc6e",
  "ee7bcea", "df5bbf7", "d96893f", "15508b3", "790ed15", "d838957",
  "aa45015", "b149b06", "c117d09", "e343ee8", "5566272", "f049cd6",
  "6dc0bc5", "37a1b4a", "f6a31ed", "08eda97", "96bf2db", "23975f5",
  "f3b0cdb", "f5ef10d", "de172b0", "3686d09", "4aec0c7");

fixes['4.9']['fixed_ver']           = '4.9.4';
fixes['4.9']['fixed_ver_display']   = '4.9.4-pre (changeset 15b4ee9)';
fixes['4.9']['affected_ver_regex']  = '^4\\.9\\.';
fixes['4.9']['affected_changesets'] = make_list("f97a1d1", "f13983d",
  "8d6f213", "c4a3f16", "1bd7c17", "1ebb803", "042887f", "e61a7cb",
  "f668bb4", "d635520", "b791d9b", "273cc99", "ee2e8a0", "f294d80",
  "782ca9b", "b7dae43", "62ed524", "75c8dbc", "56d90f5", "6000494",
  "870fcbf", "9b31834", "3eabb91");

fixes['4.10']['fixed_ver']           = '4.10.3';
fixes['4.10']['fixed_ver_display']   = '4.10.3-pre (changeset d5d8074)';
fixes['4.10']['affected_ver_regex']  = '^4\\.10\\.';
fixes['4.10']['affected_changesets'] = make_list("421aada", "e907460",
  "ba6ac89", "4c7cd94", "c841c82", "5b15c04", "6e3650d", "4d5a0f2",
  "b0f1b24", "aa05c39", "c504397", "1639352", "b79ac27", "5822be6",
  "225fbd2", "73788eb", "ed024ef", "9f8eff3", "788948b", "61dc015",
  "d86c9ae", "4519790", "5483835", "518726d", "d091a49", "923af25",
  "5ba0bb0", "173c338");

fixes['4.11']['fixed_ver']           = '4.11.1';
fixes['4.11']['fixed_ver_display']   = '4.11.1-pre (changeset 946f345)';
fixes['4.11']['affected_ver_regex']  = '^4\\.11\\.';
fixes['4.11']['affected_changesets'] = make_list("086a9dd", "dea9fc0",
  "ff9f873", "0f0ad14", "8ad462a", "d67b849", "8f3f58c", "06a50b0",
  "fe10c22", "e243639", "f0b4b69", "d34471f", "26feeb5", "221acbf",
  "8bed728", "18b5947", "94fba9f", "33664f9", "a2e35a7", "451f9c8",
  "d7cbb4b", "bb6d070", "b1a47ef", "5b1592d", "0719a5f", "03fd745",
  "d1caf6e", "a07f444", "74fee1b", "2004a91", "8c8b3cb", "5acdd26",
  "733450b", "d757c29", "6c7d074", "2a47c75", "007752f", "fb78137",
  "665e768", "f4a049e", "02d2c66", "57483c0", "d044f6c", "e6441a8",
  "48fb482", "fa79f9e", "1d32c21", "7b420e8", "8b35b97", "cfdd4e8",
  "218d403", "b52017c", "52b8f9a", "935e9c4", "61cc876", "4254e98",
  "6fe9726", "33ced72", "7de2155", "06d2a76", "543027c", "037fe82",
  "353edf1", "75313e4", "5908b48", "bd51a64", "0a2016c", "b53e0de",
  "a44cf0c", "ac35e05", "10c5482", "4bdeedb", "da33530", "e932371", "1fd87ba");

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);