Security Update for Microsoft Office Online Server and Office Web Apps (September 2017)

High Nessus Plugin ID 103192

Synopsis

An application installed on the remote Windows host is affected by multiple remote code execution vulnerabilities.

Description

The Microsoft Office Online Server or Microsoft Office Web Apps installation on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities :

- A remote code execution vulnerability exists in Microsoft Office software when it fails to properly handle objects in memory. An attacker who successfully exploited the vulnerability could use a specially crafted file to perform actions in the security context of the current user. For example, the file could then take actions on behalf of the logged-on user with the same permissions as the current user. Exploitation of this vulnerability requires that a user open a specially crafted file with an affected version of Microsoft Office software. In an email attack scenario, an attacker could exploit the vulnerability by sending the specially crafted file to the user and convincing the user to open the file. In a web-based attack scenario, an attacker could host a website (or leverage a compromised website that accepts or hosts user-provided content) that contains a specially crafted file that is designed to exploit the vulnerability. However, an attacker would have no way to force the user to visit the website. Instead, an attacker would have to convince the user to click a link, typically by way of an enticement in an email or Instant Messenger message, and then convince the user to open the specially crafted file. The security update addresses the vulnerability by correcting how Microsoft Office handles files in memory.
(CVE-2017-8631)

- A remote code execution vulnerability exists in Microsoft Office software when the software fails to properly handle objects in memory. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker could take control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
Exploitation of the vulnerability requires that a user open a specially crafted file with an affected version of Microsoft Office software. In an email attack scenario, an attacker could exploit the vulnerability by sending the specially crafted file to the user and convincing the user to open the file. In a web-based attack scenario, an attacker could host a website (or leverage a compromised website that accepts or hosts user-provided content) that contains a specially crafted file designed to exploit the vulnerability. An attacker would have no way to force users to visit the website.
Instead, an attacker would have to convince users to click a link, typically by way of an enticement in an email or instant message, and then convince them to open the specially crafted file. Note that the Preview Pane is not an attack vector for this vulnerability. The security update addresses the vulnerability by correcting how Office handles objects in memory.
(CVE-2017-8742, CVE-2017-8743)

- A remote code execution vulnerability exists due to the way Windows Uniscribe handles objects in memory. An attacker who successfully exploited this vulnerability could take control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. There are multiple ways an attacker could exploit this vulnerability: In a web-based attack scenario, an attacker could host a specially crafted website designed to exploit this vulnerability and then convince a user to view the website. An attacker would have no way to force users to view the attacker-controlled content.
Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email or instant message that takes users to the attacker's website, or by opening an attachment sent through email. In a file-sharing attack scenario, an attacker could provide a specially crafted document file designed to exploit this vulnerability and then convince a user to open the document file.The security update addresses the vulnerability by correcting how Windows Uniscribe handles objects in memory. (CVE-2017-8696)

Solution

Microsoft has released a set of patches for Microsoft Office Online Server, Office Web Apps Server 2013, Office 2010 Web Apps, and Office 2013 Web Apps.

See Also

http://www.nessus.org/u?8f1bdca6

http://www.nessus.org/u?ab979819

http://www.nessus.org/u?75d14528

https://portal.msrc.microsoft.com/en-us/security-guidance/summary

Plugin Details

Severity: High

ID: 103192

File Name: smb_nt_ms17_sep_office_web.nasl

Version: 1.8

Type: local

Agent: windows

Published: 2017/09/13

Updated: 2018/09/10

Dependencies: 13855, 27524, 93232, 84669, 57033

Risk Information

Risk Factor: High

CVSS v2.0

Base Score: 9.3

Temporal Score: 6.9

Vector: CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C

Temporal Vector: CVSS2#E:U/RL:OF/RC:C

CVSS v3.0

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:microsoft:office_web_apps, cpe:/a:microsoft:office_online_server

Required KB Items: SMB/MS_Bulletin_Checks/Possible

Exploit Available: false

Exploit Ease: No known exploits are available

Patch Publication Date: 2017/09/12

Vulnerability Publication Date: 2017/09/12

Reference Information

CVE: CVE-2017-8631, CVE-2017-8696, CVE-2017-8742, CVE-2017-8743

BID: 100741, 100746, 100751, 100780

MSKB: 3213562, 3213632, 3213658

MSFT: MS17-3213562, MS17-3213632, MS17-3213658

IAVA: 2017-A-0274