9.3 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:M/Au:N/C:C/I:C/A:C
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
0.014 Low
EPSS
Percentile
86.4%
According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a privilege escalation vulnerability due to improper bounds checking for descriptor table accesses. An authenticated attacker, in user mode on a 32-bit guest, could leverage this vulnerability to elevate privileges to that of the guest kernel. Only 32-bit PV guest user mode can leverage this vulnerability.
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.
#
# (C) Tenable Network Security, Inc.
#
include("compat.inc");
if (description)
{
script_id(130760);
script_version("1.3");
script_set_attribute(attribute:"plugin_modification_date", value:"2020/07/10");
script_cve_id("CVE-2019-18425");
script_xref(name:"IAVB", value:"2019-B-0084-S");
script_name(english:"Xen Project Descriptor Table Limit Checking Privilege Escalation Vulnerability (XSA-298)");
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 privilege escalation vulnerability due to
improper bounds checking for descriptor table accesses. An authenticated
attacker, in user mode on a 32-bit guest, could leverage this vulnerability to
elevate privileges to that of the guest kernel. Only 32-bit PV guest user mode
can leverage this vulnerability.
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-298.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:N/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:N/AC:L/PR:N/UI:N/S:U/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-2019-18425");
script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
script_set_attribute(attribute:"vuln_publication_date", value:"2019/10/31");
script_set_attribute(attribute:"patch_publication_date", value:"2019/10/31");
script_set_attribute(attribute:"plugin_publication_date", value:"2019/11/08");
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) 2019-2020 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['4.8']['fixed_ver'] = '4.8.5';
fixes['4.8']['fixed_ver_display'] = '4.8.5';
fixes['4.8']['affected_ver_regex'] = '^4\\.8\\.';
fixes['4.9']['fixed_ver'] = '4.9.4';
fixes['4.9']['fixed_ver_display'] = '4.9.4';
fixes['4.9']['affected_ver_regex'] = '^4\\.9\\.';
fixes['4.10']['fixed_ver'] = '4.10.4';
fixes['4.10']['fixed_ver_display'] = '4.10.4';
fixes['4.10']['affected_ver_regex'] = '^4\\.10\\.';
fixes['4.11']['fixed_ver'] = '4.11.3';
fixes['4.11']['fixed_ver_display'] = '4.11.3-pre';
fixes['4.11']['affected_ver_regex'] = '^4\\.11\\.';
fixes['4.12']['fixed_ver'] = '4.12.2';
fixes['4.12']['fixed_ver_display'] = '4.12.2-pre';
fixes['4.12']['affected_ver_regex'] = '^4\\.12\\.';
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) || empty_or_null(fixes[ver_branch]['affected_changesets']))
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);
9.3 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:M/Au:N/C:C/I:C/A:C
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
0.014 Low
EPSS
Percentile
86.4%