Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') in AttachmentSelector.xml

Impact

Any user with the right to edit his personal page can follow one of the scenario below:

Scenario 1:

• Log in as a simple user with just edit rights on the user profile
• Go to the user's profile
• Upload an attachment in the attachment tab at the bottom of the page (any image is fine)
• Click on "rename" in the attachment list and enter {{async async="true" cached="false" context="doc.reference"}}{{groovy}}println("Hello from groovy!"){{/groovy}}{{/async}}.png as new attachment name and submit the rename
• Go back to the user profile
• Click on the edit icon on the user avatar
• Hello from groovy! is displayed as the title of the attachment

Scenario 2:

• Log in as a simple user with just edit rights on a page
• Create a Page MyPage.WebHome
• Create an XClass field of type String named avatar
• Add an XObject of type MyPage.WebHome on the page
• Insert an attachmentSelector macro in the document with the following values:
  • classname: MyPage.WebHome
  • property: avatar
  • savemode: direct
  • displayImage: true
  • width: ]] {{async async="true" cached="false" context="doc.reference"}}{{groovy}}println("Hello from groovy!"){{/groovy}}{{/async}}. You'll find below a snippet of an attachmentSelector macro declaration.
• Display the page
• Use the attachment picker to select an image
• Hello from groovy is displayed aside the image

Example of an attachmentSelector macro declaration:

`{{attachmentSelector classname="MyPage.WebHome" property="avatar" savemode="direct" displayImage="true" width="]] {{async async=~"true~" cached=~"false~" context=~"doc.reference~"~}~}{{groovy~}~}println(~"Hello from groovy!~"){{/groovy~}~}{{/async~}~}"/}}`

Note: The issue can also be reproduced by inserting the dangerous payload in the height or alt macro properties.

Patches

The issue can be fixed on a running wiki by updating XWiki.AttachmentSelector with the versions below:

• 14.5-rc-1+: https://github.com/xwiki/xwiki-platform/commit/eb15147adf94bddb92626f862c1710d45bcd64a7#diff-e1513599ab698991f6cbba55d38f3f464432ced8d137a668b1f7618c7e747e23
• 14.4.2+: https://github.com/xwiki/xwiki-platform/commit/c02f8eb1f3c953d124f2c097021536f8bc00fa8d#diff-e1513599ab698991f6cbba55d38f3f464432ced8d137a668b1f7618c7e747e23
• 13.10.7+: https://github.com/xwiki/xwiki-platform/commit/efd0df0468d46149ba68b66660b93f31b6318515#diff-e1513599ab698991f6cbba55d38f3f464432ced8d137a668b1f7618c7e747e23

Workarounds

No known workaround.

References

• https://jira.xwiki.org/browse/XWIKI-19800

For more information

If you have any questions or comments about this advisory:

• Open an issue in Jira XWiki.org
• Email us at Security Mailing List