Vulnerabilities > CVE-2020-1226 - Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in Microsoft 365 Apps, Excel and Office

047910
CVSS 9.3 - CRITICAL
Attack vector
NETWORK
Attack complexity
MEDIUM
Privileges required
NONE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
network
microsoft
CWE-119
critical
nessus

Summary

A remote code execution vulnerability exists in Microsoft Excel software when the software fails to properly handle objects in memory, aka 'Microsoft Excel Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2020-1225.

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Overflow Buffers
    Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.
  • Client-side Injection-induced Buffer Overflow
    This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service.
  • Filter Failure through Buffer Overflow
    In this attack, the idea is to cause an active filter to fail by causing an oversized transaction. An attacker may try to feed overly long input strings to the program in an attempt to overwhelm the filter (by causing a buffer overflow) and hoping that the filter does not fail securely (i.e. the user input is let into the system unfiltered).
  • MIME Conversion
    An attacker exploits a weakness in the MIME conversion routine to cause a buffer overflow and gain control over the mail server machine. The MIME system is designed to allow various different information formats to be interpreted and sent via e-mail. Attack points exist when data are converted to MIME compatible format and back.

Nessus

NASL familyWindows : Microsoft Bulletins
NASL idSMB_NT_MS20_JUN_EXCEL.NASL
descriptionThe Microsoft Excel Products is missing a security update, and Therefore is affected by a security feature bypass vulnerability. An attacker who exploited this vulnerability could cause a system to load remote images which could disclose the IP address of the targeted system to the attacker.
last seen2020-06-13
modified2020-06-09
plugin id137264
published2020-06-09
reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/137264
titleSecurity Feature Bypass Vulnerability for Microsoft Excel Products (June 2020)
code
#
# (C) Tenable Network Security, Inc.
#

# The descriptive text and package checks in this plugin were  
# extracted from the Microsoft Security Updates API. The text
# itself is copyright (C) Microsoft Corporation.

include('compat.inc');

if (description)
{
  script_id(137264);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/17");

  script_cve_id("CVE-2020-1226");
  script_xref(name:"MSKB", value:"4484415");
  script_xref(name:"MSKB", value:"4484410");
  script_xref(name:"MSKB", value:"4484403");
  script_xref(name:"MSFT", value:"MS20-4484415");
  script_xref(name:"MSFT", value:"MS20-4484410");
  script_xref(name:"MSFT", value:"MS20-4484403");
  script_xref(name:"IAVA", value:"2020-A-0249");

  script_name(english:"Security Feature Bypass Vulnerability for Microsoft Excel Products (June 2020)");

  script_set_attribute(attribute:"synopsis", value:
"The Microsoft Excel Products are affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The Microsoft Excel Products is missing a security update, and Therefore is affected by 
a security feature bypass vulnerability. An attacker who exploited this vulnerability 
could cause a system to load remote images which could disclose the IP address of the 
targeted system to the attacker.");
  script_set_attribute(attribute:"see_also", value:"https://support.microsoft.com/en-us/help/4484415");
  script_set_attribute(attribute:"see_also", value:"https://support.microsoft.com/en-us/help/4484410");
  script_set_attribute(attribute:"see_also", value:"https://support.microsoft.com/en-us/help/4484403");
  script_set_attribute(attribute:"solution", value:
"Microsoft has released the following security updates to address this issue:  
  -KB4484415
  -KB4484410
  -KB4484403

For Office 365, Office 2016 C2R, or Office 2019, ensure automatic updates are enabled or open any office app and 
manually perform an update.");
  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:R/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-2020-1226");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/06/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/06/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/06/09");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:microsoft:excel");
  script_set_attribute(attribute:"stig_severity", value:"II");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Windows : Microsoft Bulletins");

  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("office_installed.nasl", "microsoft_office_compatibility_pack_installed.nbin", "smb_hotfixes.nasl", "ms_bulletin_checks_possible.nasl");
  script_require_keys("SMB/MS_Bulletin_Checks/Possible");
  script_require_ports(139, 445, "Host/patch_management_checks");

  exit(0);
}

include('smb_func.inc');
include('smb_hotfixes.inc');
include('smb_hotfixes_fcheck.inc');
include('smb_reg_query.inc');
include('install_func.inc');

get_kb_item_or_exit('SMB/MS_Bulletin_Checks/Possible');

bulletin = 'MS20-06';

kbs = make_list(
  '4484415',
  '4484410',
  '4484403'
);

if (get_kb_item('Host/patch_management_checks'))
  hotfix_check_3rd_party(bulletin:bulletin, kbs:kbs, severity:SECURITY_HOLE);

get_kb_item_or_exit('SMB/Registry/Enumerated', exit_code:1);

port = kb_smb_transport();

checks = make_array(
  '14.0', make_array('sp', 2, 'version', '14.0.7252.5000', 'kb', '4484415'),
  '15.0', make_array('sp', 1, 'version', '15.0.5249.1000', 'kb', '4484410'),
  '16.0', make_nested_list(make_array('sp', 0, 'version', '16.0.5017.1000', 'channel', 'MSI', 'kb', '4484403'),
    # C2R
    make_array('version', '16.0.11328.20602', 'channel', 'Deferred'),
    make_array('version', '16.0.11929.20838', 'channel', 'Deferred', 'channel_version', '1908'),
    make_array('version', '16.0.12527.20720', 'channel', 'First Release for Deferred'),
    make_array('version', '16.0.12827.20336', 'channel', 'Current'),
    # 2019
    make_array('version', '16.0.12827.20336', 'channel', '2019 Retail'),
    make_array('version', '16.0.10361.20002', 'channel', '2019 Volume')
    )
  );

if (hotfix_check_office_product(product:'Excel', checks:checks, bulletin:bulletin))
{
  replace_kb_item(name:'SMB/Missing/'+bulletin, value:TRUE);
  hotfix_security_hole();
  hotfix_check_fversion_end();
  exit(0);
}
else
{
  hotfix_check_fversion_end();
  audit(AUDIT_HOST_NOT, 'affected');
}