Microsoft Office memory corruption

Summaryinfo

A vulnerability described as critical has been identified in Microsoft Office, Excel, SharePoint Enterprise Server and 365 Apps for Enterprise. This affects an unknown function. Such manipulation leads to memory corruption. This vulnerability is documented as CVE-2020-16929. The attack can be executed remotely. There is not any exploit available. It is best practice to apply a patch to resolve this issue.

Detailsinfo

A vulnerability was found in Microsoft Office, Excel, SharePoint Enterprise Server and 365 Apps for Enterprise (Office Suite Software) (unknown version). It has been rated as critical. Affected by this issue is an unknown code block. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

<p>A remote code execution vulnerability exists in Microsoft Excel 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.</p> <p>Exploitation of the vulnerability requires that a user open a specially crafted file with an affected version of Microsoft Excel. 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) containing 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.</p> <p>The security update addresses the vulnerability by correcting how Microsoft Excel handles objects in memory.</p>

The weakness was released 10/13/2020 as confirmed security guidance (Website). The advisory is available at portal.msrc.microsoft.com. This vulnerability is handled as CVE-2020-16929. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. The advisory points out:

A remote code execution vulnerability exists in Microsoft Excel 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 Excel. 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) containing 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. The security update addresses the vulnerability by correcting how Microsoft Excel handles objects in memory.

It is declared as proof-of-concept.

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

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Productinfo

Type

• Office Suite Software

Vendor

• Microsoft

Name

• 365 Apps for Enterprise
• Excel
• Office
• SharePoint Enterprise Server

License

• commercial

Website

• Vendor: https://www.microsoft.com/

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