SecurityAdvisory19Oct2009

(legacy summary: Security Advisory 19 October 2009)

Caja Security Advisory 19-October-2009

Revision 3652 introduced changes to allow iframe shims to work around layout problems in older browsers, but did not update the default HTML schemas to block uses of iframes to load code.

Impact

These vulnerabilities allow attacking sandboxed code to completely bypass all Caja's protections if the container is using a version of the HTML schemas between revision 3652 and 3810, and is using a URI policy that does not reject or block by proxying URLs where the mime-type is text/html.

Advice

Do one of the following:

1. Best: Upgrade to a version of Caja at or after 3810.
2. Rollback to a revision prior to r3652
3. Apply the patch at http://codereview.appspot.com/download/issue124069_2001.diff to your current checkout, and rebuild.
4. Change your URI policy to block or proxy URLs where the mime-type is text/html.

More Information

The issue was originally reported at issue 1108.

The patch is available at http://codereview.appspot.com/download/issue124069_2001.diff and discussion of the change at http://codereview.appspot.com/124069/show.

CajaWhitelists explains how to modify HTML and CSS schemas, and UriPolicy explains URI policies.