DSpace Cross Site Scripting (XSS) via a deposited HTML/XML document

Impact

In DSpace 7.0 through 7.6.1, when an HTML, XML or JavaScript Bitstream is downloaded, the user’s browser may execute any embedded JavaScript. If that embedded JavaScript is malicious, there is a risk of an XSS attack.

This attack may only be initialized by a user who already has Submitter privileges in the repository. The submitter must upload the malicious HTML/XML/JavaScript file themselves. The attack itself would not occur until a visitor or logged-in user downloads the file or clicks on a download link shared by the attacker.

If your site is running the frontend and backend from separate domains, CORS and CSRF protection built into DSpace help to limit the impact of the attack.

If the repository is configured to only download HTML / XML / JavaScript Bitstreams using the Content-Disposition: attachment header, then the attack is no longer possible. See “Workarounds” below.

Patches

The fix is included in both 8.0 and 7.6.2. Please upgrade to one of these versions, or manually apply one of the “Workarounds” below.

If you are already running 7.6 or 7.6.1, then this vulnerability can be fixed via a configuration update in your dspace.cfg configuration file. See details in below.

Workarounds

DSpace sites running 7.6 or 7.6.1 can fix this issue by adding the following webui.content_disposition_format settings to their dspace.cfg (or local.cfg). These settings force all HTML, XML, RDF & JavaScript files to always be downloaded to a user’s machine, blocking the attack. For more details see PR #9638

webui.content_disposition_format = text/html
webui.content_disposition_format = text/javascript
webui.content_disposition_format = text/xml
webui.content_disposition_format = rdf

These settings will take effect immediately. There is no need to restart Tomcat.

To verify the settings are working: upload an HTML or XML file to an in-progress submission. Attempt to download the file. The file should not open in your browser window. Instead, it should download to your local computer.

DSpace sites running 7.0 through 7.5 will need toeither (CHOOSE ONE):

• Upgrade to 7.6.2 or 8.0
• Or, upgrade to 7.6 or 7.6.1 and then apply the configuration change mentioned above
• Or, manually add the webui.content_disposition_format setting (which was first released in 7.6), and then apply the configuration changes mentioned above.
  • The webui.content_disposition_format setting can be added by applying the changes in PR #8891. A patch file is also available.
  • Please be aware this patch may not apply cleanly to all prior versions of 7.x. In that scenario, you would need to find a way to manually apply the changes or consider a different workaround.
• Or, find a way in your Apache or NGinx proxy to force the Content-Disposition: attachment header to be sent for all files downloaded via /server/api/core/bitstreams/[uuid]/content in the REST API.
  • NOTE: This workaround will patch the vulnerability. However, it does so by no longer allowing users to open any downloaded files in their browser window. (This behavior may or may not be desirable in the long term, so you may wish to remove it in the future, once you have upgraded.)
  • For example, in Apache, using “mod_headers”, you may add a configuration similar to this in your <VirtualHost>:

    # Set "Content-Disposition: attachment" whenever path is /server/api/core/bitstreams/[uuid]/content
    Header set Content-Disposition attachment "expr=%{REQUEST_URI} =~ m#^/server/api/core/bitstreams/.*/content$#"
    

References

Discovered and reported by Muhammad Zeeshan (Xib3rR4dAr)

For more information

If you have any questions or comments about this advisory:

• Email us at [email protected]