CVE-2023-2255: Unauthorized Access to External Links in LibreOffice Editor Components

The CVE-2023-2255 vulnerability affecting The Document Foundation's LibreOffice suite was identified in the software's editor components. This security flaw allowed for the improper access and control of externally linked content through the use of 'floating frames' without any user validation. In this article, we will cover the technical details of this vulnerability, the affected LibreOffice versions, and the exploit methods used by attackers to manipulate internal links in LibreOffice documents.

CVE-2023-2255 Vulnerability Details

The CVE-2023-2255 vulnerability can be found in the editor components of The Document Foundation LibreOffice suite. It specifically affects the way in which the software handles external links embedded within the document and tied to 'floating frames.' When a user opens a document containing one or more of these floating frames linked to external files, the LibreOffice software will automatically load the content of the frames without any input or consent from the user. This oversight in access control usability creates an inconsistency with how the application handles other types of linked content and consequently puts users at risk of unauthorized access to external files.

Affected Versions

The CVE-2023-2255 vulnerability affects the following versions of LibreOffice software from The Document Foundation:

Code Snippet

An example of the code used to create "floating frames" with external links in a vulnerable LibreOffice document could look like the following:

<text:p>
  <draw:frame text:anchor-type="paragraph" svg:width="10cm" draw:name="Floating_Frame">
    <draw:text-box xlink:href="https://www.example.com/external_link"; />
  </draw:frame>
</text:p>

This code snippet shows how an attacker could maliciously embed an external link, specifically utilizing the 'xlink:href' attribute of the 'draw:text-box' element to reference a remote website or content file.

Exploit Details

To exploit the CVE-2023-2255 vulnerability, an attacker needs to craft and distribute a LibreOffice document containing one or more floating frames with external links. When such a document is opened by a user running an affected version of LibreOffice software, the unauthorized content will automatically load, potentially exposing sensitive data or introducing undesired content. This could be used by an attacker for various purposes, including the distribution of malware or phishing attacks.

Mitigation Measures

Users are strongly encouraged to update their LibreOffice software to the most recent version containing patches for the CVE-2023-2255 vulnerability:

* LibreOffice 7.5: upgrade to version 7.5.3 or later

As a general rule, users should also be cautious when opening documents from unknown sources, even when they appear to be legitimate LibreOffice files.

For more information on this vulnerability, please refer to the following resources

* The Document Foundation - Release Notes: https://www.libreoffice.org/download/release-notes/
 * CVE-2023-2255 Official CVE Record: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-2255

Conclusion

The CVE-2023-2255 vulnerability highlights the importance of software updates and user vigilance in the context of document sharing. By staying informed about the latest security developments and maintaining up-to-date software, users can minimize the risks associated with unauthorized access to external content and resources.

Timeline

Published on: 05/25/2023 20:15:00 UTC
Last modified on: 06/01/2023 17:34:00 UTC