Xen Hypervisor XENMEM_exchange Memory Disclosure (XSA-212)

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

include("compat.inc");

if (description)
{
  script_id(99399);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/06/03");

  script_cve_id("CVE-2017-7228");
  script_bugtraq_id(97375);
  script_xref(name:"IAVB", value:"2017-B-0042-S");

  script_name(english:"Xen Hypervisor XENMEM_exchange Memory Disclosure (XSA-212)");
  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 out-of-array memory
access error in the memory_exchange() function in file common/memory.c
due to improper checking of XENMEM_exchange input. An attacker on a
64-bit PV guest VM who has administrative privileges can exploit this
issue to access arbitrary system memory locations, which can then be
potentially used for further compromising 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:"https://xenbits.xen.org/xsa/advisory-212.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:H/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:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2017/04/04");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/04/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/04/14");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:xen:xen");
  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  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 Tenable Network Security, Inc.");

  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 cde86fc)';
fixes['4.5']['affected_ver_regex']  = '^4\\.5\\.';
fixes['4.5']['affected_changesets'] = make_list("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-pre (changeset ef63a62)';
fixes['4.6']['affected_ver_regex']  = '^4\\.6\\.';
fixes['4.6']['affected_changesets'] = make_list("f96efeb", "7ff6d9f",
  "7017321", "541ad61", "4f96171", "9eb0aa2", "ac4c5d4", "18949dc",
  "eea0742", "90ae9a7", "ef5eb08", "48c3bd0");

fixes['4.7']['fixed_ver']           = '4.7.3';
fixes['4.7']['fixed_ver_display']   = '4.7.3-pre (changeset 4bd66bc)';
fixes['4.7']['affected_ver_regex']  = '^4\\.7\\.';
fixes['4.7']['affected_changesets'] = make_list("47ba140", "4a1dc28",
  "5466c77", "25f3d95", "e5e7f35", "683b886", "9f2540d", "9d9be1e",
  "ac8d90e", "bc868a2", "d5f9489", "b2a180e", "01abcc0", "9c404df",
  "ddc0cfe", "9a54dcd", "4351611", "c782e61", "d166f07", "099f67b",
  "d756bf1", "10debc0", "461dba2", "188809f", "3daa62a");

fixes['4.8']['fixed_ver']           = '4.8.1';
fixes['4.8']['fixed_ver_display']   = '4.8.1-pre (changeset 06403aa)';
fixes['4.8']['affected_ver_regex']  = '^4\\.8\\.';
fixes['4.8']['affected_changesets'] = make_list("f3623bd", "c95bad9",
  "4ec1cb0", "093a1f1", "47501b6", "2859b25", "ca41491", "26dec7a",
  "eca97a4", "c75fe64", "af18ca9", "30c2dd7", "1780ea7", "42290f0",
  "bd684c2", "783b670", "07f9ddf", "d31d0cd", "b2e678e", "05946b5",
  "e020ff3", "308c646", "fceae91", "f667393", "768b250", "049b13d",
  "e26a2a0", "866f363", "354c3e4", "8c2da8f", "6289c3b", "2e68fda",
  "f85fc97", "9967251", "34305da", "437a8e6", "9028ba8", "1c28394",
  "c246296", "10baa19", "4582c2b", "a20300b", "23e3303", "95f1f99",
  "9b0e6d3", "b843de7", "ba7e250", "6240d92", "b378b1f", "b29aed8",
  "e1cefed", "53c3a73", "daf491d", "a654228", "c581ead", "67e9679",
  "080a31b", "1febe8d", "7713ee2", "b76a796", "e298344", "6933092",
  "af6534e", "297cf3d", "3e902dd", "c5efe95", "63c68c7", "3667bc0",
  "86e54be", "e7ad85e", "bdbfca0", "443264e", "d575902", "24ccfc3",
  "7628c7e", "b996efb", "7967daf", "1f4ea16");

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);