Package Instance

Cross-Site Request Forgery (CSRF)
XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. The create action is vulnerable to a CSRF attack, allowing script and thus remote code execution when targeting a user with script/programming right, thus compromising the confidentiality, integrity and availability of the whole XWiki installation. When a user with script right views this image and a log message `ERROR foo - Script executed!` appears in the log, the XWiki installation is vulnerable. This has been patched in XWiki 14.10.9 and 15.4RC1 by requiring a CSRF token for the actual page creation.

Missing Authorization
XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. It is possible in XWiki to execute Velocity code without having script right by creating an XClass with a property of type "TextArea" and content type "VelocityCode" or "VelocityWiki". For the former, the syntax of the document needs to be set the `xwiki/1.0` (this syntax does not need to be installed). In both cases, when adding the property to an object, the Velocity code is executed regardless of the rights of the author of the property (edit right is still required, though). In both cases, the code is executed with the correct context author so no privileged APIs can be accessed. However, Velocity still grants access to otherwise inaccessible data and APIs that could allow further privilege escalation. At least for "VelocityCode", this behavior is most likely very old but only since XWiki 7.2, script right is a separate right, before that version all users were allowed to execute Velocity and thus this was expected and not a security issue. This has been patched in XWiki 14.10.10 and 15.4 RC1. Users are advised to upgrade. There are no known workarounds.

Incomplete Cleanup
XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. When an XWiki installation is upgraded and that upgrade contains a fix for a bug in a document, just a new version of that document is added. In some cases, it's still possible to exploit the vulnerability that was fixed in the new version. The severity of this depends on the fixed vulnerability, for the purpose of this advisory take CVE-2022-36100/GHSA-2g5c-228j-p52x as example - it is easily exploitable with just view rights and critical. When XWiki is upgraded from a version before the fix for it (e.g., 14.3) to a version including the fix (e.g., 14.4), the vulnerability can still be reproduced by adding `rev=1.1` to the URL used in the reproduction steps so remote code execution is possible even after upgrading. Therefore, this affects the confidentiality, integrity and availability of the whole XWiki installation. This vulnerability also affects manually added script macros that contained security vulnerabilities that were later fixed by changing the script macro without deleting the versions with the security vulnerability from the history. This vulnerability does not affect freshly installed versions of XWiki. Further, this vulnerability does not affect content that is only loaded from the current version of a document like the code of wiki macros or UI extensions. This vulnerability has been patched in XWiki 14.10.7 and 15.2RC1 by forcing old revisions to be executed in a restricted mode that disables all script macros. As a workaround, admins can manually delete old revisions of affected documents. A script could be used to identify all installed documents and delete the history for them. However, also manually added and later corrected code may be affected by this vulnerability so it is easy to miss documents.

XWiki Platform remote code execution from account via custom skins support
### Impact
Any user who can edit any page like their profile can create a custom skin with a template override that is executed with programming right, thus allowing remote code execution. 

To reproduce, as a user without edit, script or admin right, add an object of class `XWiki.XWikiSkins` to your profile. Name it whatever you want and set the Base Skin to `flamingo`.
Add an object of class `XWikiSkinFileOverrideClass` and set the path to `macros.vm` and the content to:
```
#macro(mediumUserAvatar $username)
  #resizedUserAvatar($username 50)
  $services.logging.getLogger('Skin').error("I got programming: $services.security.authorization.hasAccess('programming')")
#end
```
Back to your profile, click `Test this skin`. Force a refresh, just in case.
If the error "Skin - I got programming: true" gets logged, the installation is vulnerable.

### Patches
This has been patched in XWiki 14.10.19, 15.5.4 and 15.10RC1.

### Workarounds
We're not aware of any workaround except upgrading.

### References
* https://jira.xwiki.org/browse/XWIKI-21478
* https://github.com/xwiki/xwiki-platform/commit/3d4dbb41f52d1a6e39835cfb1695ca6668605a39 (>= 15.8 RC1)
* https://github.com/xwiki/xwiki-platform/commit/da177c3c972e797d92c1a31e278f946012c41b56 (< 15.8 RC1)

XWiki Platform: Password hash might be leaked by diff once the xobject holding them is deleted
### Impact

It is possible to access the hash of a password by using the diff feature of the history whenever the object storing the password is deleted. Using that vulnerability it's possible for an attacker to have access to the hash password of a user if they have rights to edit the users' page. 

Now with the default right scheme in XWiki this vulnerability is normally prevented on user profiles, except by users with Admin rights. Note that this vulnerability also impacts any extensions that might use passwords stored in xobjects: for those usecases it depends on the right of those pages.

There is currently no way to be 100% sure that this vulnerability has been exploited, as an attacker with enough privilege could have deleted the revision where the xobject was deleted after rolling-back the deletion. But again, this operation requires high privileges on the target page (Admin right). A page with a user password xobject which have in its history a revision where the object has been deleted should be considered at risk and the password should be changed there.

### Patches

The vulnerability has been patched in XWiki 14.10.19, 15.5.4 and 15.9-rc-1 by performing a better check before dislaying data of a diff, to ensure it's not coming from a password field. 

### Workarounds

Admins should ensure that the user pages are properly protected: the edit right shouldn't be allowed for other users than Admin and owner of the profile (which is the default right). 
Now there's not much workaround possible for a privileged user other than upgrading XWiki. 

### References

* JIRA ticket: https://jira.xwiki.org/browse/XWIKI-19948
* Commit: https://github.com/xwiki/xwiki-platform/commit/f1eaec1e512220fabd970d053c627e435a1652cf

### For more information

If you have any questions or comments about this advisory:
* Open an issue in [Jira XWiki.org](https://jira.xwiki.org/)
* Email us at [Security Mailing List](mailto:security@xwiki.org)

XWiki Platform allows remote code execution from user account
### Impact
When an admin disables a user account, the user's profile is executed with the admin's rights. This allows a user to place malicious code in the user profile before getting an admin to disable the user account.

To reproduce, as a user without script nor programming rights, edit the about section of your user profile and add `{{groovy}}services.logging.getLogger("attacker").error("Hello from Groovy!"){{/groovy}}`.
As an admin, go to the user profile and click the "Disable this account" button.
Then, reload the page. If the logs show `attacker - Hello from Groovy!` then the instance is vulnerable.

### Patches
This has been patched in XWiki 14.10.21, 15.5.5, 15.10.6 and 16.0.0.

### Workarounds
We're not aware of any workaround except upgrading.

### References
* https://jira.xwiki.org/browse/XWIKI-21611
* https://github.com/xwiki/xwiki-platform/commit/f89c8f47fad6e5cc7e68c69a7e0acde07f5eed5a

XWiki Platform: Privilege escalation (PR) from user registration through PDFClass
### Impact
Remote code execution is possible via PDF export templates.
To reproduce on an installation, register a new user account with username `PDFClass` if `XWiki.PDFClass` does not exist.
On `XWiki.PDFClass`, use the class editor to add a "style" property of type "TextArea" and content type "Plain Text".
Then, add an object of class `PDFClass` and set the "style" attribute to `$services.logging.getLogger('PDFClass').error("I got programming: $services.security.authorization.hasAccess('programming')")`.
Finally, go to `<host>/xwiki/bin/export/Main/WebHome?format=pdf&pdftemplate=XWiki.PDFClass`. If the logs contain "ERROR PDFClass - I got programming: true", the instance is vulnerable.

### Patches
This vulnerability has been patched in XWiki 14.10.20, 15.5.4 and 15.10-rc-1.

### Workarounds
If PDF templates are not typically used on the instance, an administrator can create the document `XWiki.PDFClass` and block its edition, after making sure that it does not contain a `style` attribute.
Otherwise, the instance needs to be updated.

### References
- https://jira.xwiki.org/browse/XWIKI-21337
- https://github.com/xwiki/xwiki-platform/commit/d28e21a670c69880b951e415dd2ddd69d273eae9

org.xwiki.platform:xwiki-platform-oldcore may leak data through deleted and re-created documents
XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Starting in version 9.4-rc-1 and prior to versions 14.10.8 and 15.3-rc-1, when a document has been deleted and re-created, it is possible for users with view right on the re-created document but not on the deleted document to view the contents of the deleted document. Such a situation might arise when rights were added to the deleted document. This can be exploited through the diff feature and, partially, through the REST API by using versions such as `deleted:1` (where the number counts the deletions in the wiki and is thus guessable). Given sufficient rights, the attacker can also re-create the deleted document, thus extending the scope to any deleted document as long as the attacker has edit right in the location of the deleted document. This vulnerability has been patched in XWiki 14.10.8 and 15.3 RC1 by properly checking rights when deleted revisions of a document are accessed. The only workaround is to regularly clean deleted documents to minimize the potential exposure. Extra care should be taken when deleting sensitive documents that are protected individually (and not, e.g., by being placed in a protected space) or deleting a protected space as a whole.

XWiki Platform allows XSS through XClass name in string properties
### Impact
Is it possible for a user without Script or Programming rights to craft a URL pointing to a page with arbitrary JavaScript.
This requires social engineer to trick a user to follow the URL.

#### Reproduction steps

1. As a user without script or programming right, create a (non-terminal) document named `" + alert(1) + "` (the quotes need to be part of the name).
1. Edit the class.
1. Add a string property named `"test"`.
1. Edit using the object editor and add an object of the created class
1. Get an admin to open `<xwiki-server>/xwiki/bin/view/%22%20%2B%20alert(1)%20%2B%20%22/?viewer=display&type=object&property=%22%20%2B%20alert(1)%20%2B%20%22.WebHome.test&mode=edit` where `<xwiki-server>` is the URL of your XWiki installation.

### Patches
This has been patched in XWiki 14.10.21, 15.5.5, 15.10.6 and 16.0.0.

### Workarounds

We're not aware of any workaround except upgrading.

### References
- https://jira.xwiki.org/browse/XWIKI-21810
- https://github.com/xwiki/xwiki-platform/commit/27eca8423fc1ad177518077a733076821268509c