Threat Level: green Handler on Duty: Didier Stevens

SANS ISC: Scans for FCKEditor File Manager - SANS Internet Storm Center SANS ISC InfoSec Forums

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Scans for FCKEditor File Manager

FCKEditor (now known as CKEditor [1]) is a popular full featured GUI editor many web sites use. For example, you frequently find it with blog systems like WordPress or as part of commenting/forum systems. As an additional feature, a filemanager can be added to allow users to upload images or other files. Sadly, while a very nice and functional plugin, this features if frequently not well secured and can be used to upload malicious files. We have seen some scans probing specifically for this file manager plugin:

HEAD /js/fckeditor/editor/filemanager/connectors/test.html 
HEAD /admin/FCKeditor/editor/filemanager/connectors/test.html 
HEAD /admin/FCKeditor/editor/fckeditor.html
HEAD /include/fckeditor/_samples/default.html 
HEAD /include/fckeditor/editor/filemanager/connectors/test.html
These requests did not set a user agent or a referrer. The following set did however use "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; SV1;" and instead of a HEAD request it used a GET request, indicating that there are different distinct tools looking for the same vulnerability:
GET /editor/editor/filemanager/connectors/uploadtest.html HTTP/1.1
GET /editor/editor/filemanager/upload/test.html HTTP/1.1
GET /editor/editor/filemanager/browser/default/connectors/test.html HTTP/1.1
GET /editor/editor/filemanager/connectors/test.html HTTP/1.1
GET /admin/fckeditor/editor/filemanager/connectors/test.html HTTP/1.1
GET /FCKeditor/editor/filemanager/upload/test.html HTTP/1.1
GET /Fckeditor/editor/filemanager/browser/default/connectors/test.html HTTP/1.1
GET /admin/FCKeditor/editor/filemanager/connectors/uploadtest.html HTTP/1.1
GET /admin/FCKeditor/editor/filemanager/upload/test.html HTTP/1.1
GET /Fckeditor/editor/filemanager/connectors/test.html HTTP/1.1
GET /admin/fckeditor/editor/filemanager/browser/default/connectors/test.html HTTP/1.1
GET /FCKeditor/editor/filemanager/connectors/uploadtest.html HTTP/1.1

I am still looking for any samples of files these script attempt to upload. If you got any, please let use know.


Johannes B. Ullrich, Ph.D.
SANS Technology Institute

I will be teaching next: Application Security: Securing Web Apps, APIs, and Microservices - SANS Cyber Defence Japan August 2022


4511 Posts
ISC Handler
Mar 18th 2014
i get the following gets

got a bunch of these over the past two days,

noticed some webshell attempt alerts on the IDS, i guess they auto try to upload some files via fskeditor or whatever, and in the same breath try to reach the asp webshell to see if it worked.

37 Posts

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