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

Summaryinfo

A vulnerability, which was classified as problematic, was found in Microsoft SharePoint Server 2013 SP1/2016/2019. This issue affects some unknown processing. Such manipulation leads to cross site scripting. This vulnerability is traded as CVE-2020-16945. The attack may be launched remotely. There is no exploit available. Applying a patch is advised to resolve this issue.

Detailsinfo

A vulnerability was found in Microsoft SharePoint Server 2013 SP1/2016/2019 (Groupware Software). It has been rated as problematic. Affected by this issue is some unknown functionality. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to 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. Impacted is integrity. CVE summarizes:

<p>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.</p> <p>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.</p> <p>The security update addresses the vulnerability by helping to ensure that SharePoint Server properly sanitizes web requests.</p>

The weakness was shared 10/13/2020 as confirmed security guidance (Website). The advisory is shared for download at portal.msrc.microsoft.com. This vulnerability is handled as CVE-2020-16945. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.007. The advisory points out:

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.

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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