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[oCERT-2009-007] FCKeditor input sanitization errors
Jul 03 2009 03:45PM
Andrea Barisani (lcars ocert org)
#2009-007 FCKeditor input sanitization errors
FCKeditor, a web based open source HTML text editor, suffers from a remote
file upload vulnerability.
The input of several connector modules is not properly verified before being
used, this leads to exposure of the contents of arbitrary directories on the
server filesystem and allows file uploading to arbitrary locations. The
affected code is remotely exposed before authentication. An attacker can
exploit this vulnerability to install remote shells on the victim server
among other things, it should be noted that this vulnerability is being
actively exploited in the wild.
Additionally several XSS vulnerabilities are present in the packaged samples
A patch and a new FCKeditor version will be made available on Monday July 6th
16:00 CET, this advisory will be updated with detailed information about the
issue and a security patch.
In the meantime we strongly recommend to implement the following
* removed unused connectors from 'editor\filemanager\connectors'
* disable the file browser in config.ext
* inspect all fckeditor folders on the server for suspicious files that
may have been previously uploaded, as an example image directories
(eg. 'fckeditor/editor/images/...') are well known target locations
for remote php shells with extensions that match image files
* completely remove the '_samples' directory
FCKeditor <= 2.6.4
(version 3.0 is unaffected as it does not have any built-in file browser)
FCKeditor >= 18.104.22.168 (to be released on 2009-07-06 16:00 CET)
Credit: vulnerability report received from Vinny Guido <bigvin [at]
hushmail [dot] com>.
2009-05-03: vulnerability reported received
2009-05-04: contacted fckeditor maintainer
2009-05-25: maintainer denies reported issues against latest version
2009-05-25: reporter confirms that latest version is affected
2009-06-21: maintainer forwards report to project security maintainer
2009-06-23: security maintainer confirms CurrentFolder vulnerability
2009-06-24: security maintainer provides patch
2009-06-29: assigned CVE
2009-07-03: preliminary advisory release with mitigation instructions due to
wide exposure of the issue
Andrea Barisani | Founder & Project Coordinator
oCERT | Open Source Computer Emergency Response Team
<lcars (at) ocert (dot) org [email concealed]> http://www.ocert.org
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"Pluralitas non est ponenda sine necessitate"
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