Microsoft Patch Tuesday — Aug. 2019: Vulnerability disclosures and Snort coverage

A remote code execution vulnerability exists when Windows Hyper-V Network Switch on a host server fails to properly validate input from an authenticated user on a guest operating system, aka 'Hyper-V Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2019-0721.

A remote code execution vulnerability exists in Remote Desktop Services – formerly known as Terminal Services – when an unauthenticated attacker connects to the target system using RDP and sends specially crafted requests. This vulnerability is pre-authentication and requires no user interaction. An attacker who successfully exploited this vulnerability could execute arbitrary code on the target system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. To exploit this vulnerability, an attacker would need to send a specially crafted request to the target systems Remote Desktop Service via RDP. The update addresses the vulnerability by correcting how Remote Desktop Services handles connection requests.

A remote code execution vulnerability exists in the way that the Chakra scripting engine handles objects in memory in Microsoft Edge (HTML-based). The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited the vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability through Microsoft Edge (HTML-based) and then convince a user to view the website. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements. These websites could contain specially crafted content that could exploit the vulnerability. The security update addresses the vulnerability by modifying how the Chakra scripting engine handles objects in memory.

A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer. The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited the vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability through Internet Explorer and then convince a user to view the website. An attacker could also embed an ActiveX control marked "safe for initialization" in an application or Microsoft Office document that hosts the IE rendering engine. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements. These websites could contain specially crafted content that could exploit the vulnerability. The security update addresses the vulnerability by modifying how the scripting engine handles objects in memory.

A remote code execution vulnerability exists in Microsoft Word 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. The file could then take actions on behalf of the logged-on user with the same permissions as the current user. To exploit the vulnerability, a user must open a specially crafted file with an affected version of Microsoft Word software. Two possible email attack scenarios exist for this vulnerability: With the first email attack scenario, an attacker could send a specially crafted email message to the user and wait for the user to click on the message. When the message renders via Microsoft Word in the Outlook Preview Pane, an attack could be triggered. With the second scenario, an attacker could attach a specially crafted file to an email, send it to a user, and convince them to open it. 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 other message, and then convince the user to open the specially crafted file. The security update addresses the vulnerability by correcting how Microsoft Word handles files in memory. For users who view their emails in Outlook, the Preview Pane attack vector can be mitigated by disabling this feature. The following registry keys can be set to disable the Preview Pane in Outlook on Windows, either via manual editing of the registry or by modifying Group Policy. Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Outlook 2010: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Options DWORD: DisableReadingPane Value: 1 Outlook 2013: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Options DWORD: DisableReadingPane Value: 1 Outlook 2016, Outlook 2019, and Office 365 ProPlus: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options DWORD: DisableReadingPane Value: 1

An elevation of privilege vulnerability exists in Windows when the Windows kernel-mode driver fails to properly handle objects in memory. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take control of an affected system. The update addresses this vulnerability by correcting how the Windows kernel-mode driver handles objects in memory.

Rejected reason: DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: none. Reason: This candidate was in a CNA pool that was not assigned to any issues during 2019. Notes: none

An elevation of privilege vulnerability exists when the MpSigStub.exe for Defender allows file deletion in arbitrary locations. To exploit the vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted command that could exploit the vulnerability and delete protected files on an affected system once MpSigStub.exe ran again. The update addresses the vulnerability and blocks the arbitrary deletion.

A cross-site-scripting (XSS) vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted web request to an affected SharePoint server. An authenticated attacker could exploit the vulnerability by sending a specially crafted request to an affected SharePoint server. The attacker who successfully exploited the vulnerability could then perform cross-site scripting attacks on affected systems and run script in the security context of the current user. The attacks could allow the attacker to read content that the attacker is not authorized to read, use the victim's identity to take actions on the SharePoint site on behalf of the user, such as change permissions and delete content, and inject malicious content in the browser of the user. The security update addresses the vulnerability by helping to ensure that SharePoint Server properly sanitizes web requests.

A memory corruption vulnerability exists in the Windows Server DHCP service when an attacker sends specially crafted packets to a DHCP failover server. An attacker who successfully exploited the vulnerability could cause the DHCP service to become nonresponsive. To exploit the vulnerability, an attacker could send a specially crafted packet to a DHCP server. However, the DHCP server must be set to failover mode for the attack to succeed. The security update addresses the vulnerability by correcting how DHCP failover servers handle network packets.

An elevation of privilege vulnerability exists in Git for Visual Studio when it improperly parses configuration files. An attacker who successfully exploited the vulnerability could execute code in the context of another local user. To exploit the vulnerability, an authenticated attacker would need to modify Git configuration files on a system prior to a full installation of the application. The attacker would then need to convince another user on the system to execute specific Git commands. The update addresses the issue by changing the permissions required to edit configuration files.

A memory corruption vulnerability exists in the Windows Server DHCP service when an attacker sends specially crafted packets to a DHCP server. An attacker who successfully exploited the vulnerability could run arbitrary code on the DHCP server. To exploit the vulnerability, an attacker could send a specially crafted packet to a DHCP server. The security update addresses the vulnerability by correcting how DHCP servers handle network packets.

A spoofing vulnerability exists in the way Microsoft Outlook iOS software parses specifically crafted email messages. An authenticated attacker could exploit the vulnerability by sending a specially crafted email message to a victim. The attacker who successfully exploited this vulnerability could then perform cross-site scripting attacks on the affected systems and run scripts in the security context of the current user. The security update addresses the vulnerability by correcting how Outlook iOS parses specially crafted email messages.

An elevation of privilege vulnerability exists in Dynamics On-Premise v9. An attacker who successfully exploited the vulnerability could leverage a customizer privilege within Dynamics to gain control of the Web Role hosting the Dynamics installation. To exploit this vulnerability, an attacker needs to have credentials for a user that has permission to author customized business rules in Dynamics, and persist XAML script in a way that causes it to be interpreted as code. The update addresses the vulnerability by restricting XAML activities to a whitelisted set.

The Bluetooth BR/EDR specification up to and including version 5.1 permits sufficiently low encryption key length and does not prevent an attacker from influencing the key length negotiation. This allows practical brute-force attacks (aka "KNOB") that can decrypt traffic and inject arbitrary ciphertext without the victim noticing.

Some HTTP/2 implementations are vulnerable to ping floods, potentially leading to a denial of service. The attacker sends continual pings to an HTTP/2 peer, causing the peer to build an internal queue of responses. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.