Microsoft SharePoint Server 2013 SP1/2016/2019 cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Microsoft SharePoint Server 2013 SP1/2016/2019. This vulnerability affects unknown code. This manipulation causes cross site scripting. This vulnerability appears as CVE-2020-16944. The attack may be initiated remotely. There is no available exploit. It is recommended to apply a patch to fix this issue.

Detailsinfo

A vulnerability was found in Microsoft SharePoint Server 2013 SP1/2016/2019 (Groupware Software). It has been declared as problematic. Affected by this vulnerability is an unknown functionality. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

<p>This vulnerability is caused when SharePoint Server does not properly sanitize a specially crafted request to an affected SharePoint server.</p> <p>An authenticated attacker could exploit this vulnerability by sending a specially crafted request to an affected SharePoint server. The attacker who successfully exploited this vulnerability could then perform cross-site scripting attacks on affected systems and run script in the security context of the current user. These 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 victim, such as change permissions, delete content, steal sensitive information (such as browser cookies) and inject malicious content in the browser of the victim.</p> <p>For this vulnerability to be exploited, a user must click a specially crafted URL that takes the user to a targeted SharePoint Web App site.</p> <p>In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user of the targeted SharePoint Web App site and convincing the user to click the specially crafted URL.</p> <p>In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL to the targeted SharePoint Web App site that is used to attempt to exploit these vulnerabilities. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit the vulnerability. An attacker would have no way to force users to visit a specially crafted website. Instead, an attacker would have to convince them to visit the website, typically by getting them to click a link in an instant messenger or email message that takes them to the attacker's website, and then convince them to click the specially crafted URL.</p> <p>The security update addresses the vulnerability by helping to ensure that SharePoint Server properly sanitizes user web requests.</p>

The weakness was presented 10/13/2020 as confirmed security guidance (Website). It is possible to read the advisory at portal.msrc.microsoft.com. This vulnerability is known as CVE-2020-16944. The exploitation appears to be easy. The attack can be launched remotely. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK. The advisory points out:

This vulnerability is caused when SharePoint Server does not properly sanitize a specially crafted request to an affected SharePoint server. An authenticated attacker could exploit this vulnerability by sending a specially crafted request to an affected SharePoint server. The attacker who successfully exploited this vulnerability could then perform cross-site scripting attacks on affected systems and run script in the security context of the current user. These 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 victim, such as change permissions, delete content, steal sensitive information (such as browser cookies) and inject malicious content in the browser of the victim. For this vulnerability to be exploited, a user must click a specially crafted URL that takes the user to a targeted SharePoint Web App site. In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user of the targeted SharePoint Web App site and convincing the user to click the specially crafted URL. In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL to the targeted SharePoint Web App site that is used to attempt to exploit these vulnerabilities. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit the vulnerability. An attacker would have no way to force users to visit a specially crafted website. Instead, an attacker would have to convince them to visit the website, typically by getting them to click a link in an instant messenger or email message that takes them to the attacker's website, and then convince them to click the specially crafted URL. The security update addresses the vulnerability by helping to ensure that SharePoint Server properly sanitizes user web requests.

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

• Groupware Software

Vendor

• Microsoft

Name

• SharePoint Server

Version

• 2013 SP1
• 2016
• 2019

License

• commercial

Website

• Vendor: https://www.microsoft.com/

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