Microsoft Windows up to Server 2019 Font Library out-of-bounds write

Summaryinfo

A vulnerability has been found in Microsoft Windows and classified as critical. This issue affects some unknown processing of the component Font Library. This manipulation causes input validation. This vulnerability is handled as CVE-2019-1152. The attack can be initiated remotely. Additionally, an exploit exists. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability has been found in Microsoft Windows (Operating System) and classified as critical. Affected by this vulnerability is an unknown part of the component Font Library. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A remote code execution vulnerability exists when the Windows font library improperly handles specially crafted embedded fonts. An attacker who successfully exploited the 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 the vulnerability: In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability and then convince users 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 the vulnerability and then convince users to open the document file. The security update addresses the vulnerability by correcting how the Windows font library handles embedded fonts.

The weakness was released 08/13/2019 as confirmed security update guide (Website). It is possible to read the advisory at portal.msrc.microsoft.com. The public release was coordinated with Microsoft. This vulnerability is known as CVE-2019-1152 since 11/26/2018. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are unknown but a public exploit is available. The advisory points out:

A remote code execution vulnerability exists when the Windows font library improperly handles specially crafted embedded fonts. An attacker who successfully exploited the 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.

It is possible to download the exploit at exploit-db.com. It is declared as proof-of-concept. We expect the 0-day to have been worth approximately $25k-$100k.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Exploit-DB (47268). Entries connected to this vulnerability are available at VDB-139895, VDB-139894, VDB-139893 and VDB-139890. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 7 SP1
• 8.1
• 10
• 10 1607
• 10 1703
• 10 1709
• 10 1803
• 10 1809
• 10 1903
• RT 8.1
• Server 1803
• Server 1903
• Server 2008 R2 SP1
• Server 2008 SP2
• Server 2012
• Server 2012 R2
• Server 2016
• Server 2019

License

• commercial

Website

• Vendor: https://www.microsoft.com/
• Product: https://www.microsoft.com/en-us/windows

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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