FCKEditor Core ASP 2.6.8 – Arbitrary File Upload Protection Bypass
- Title: FCKEditor 2.6.8 ASP Version File Upload Protection bypass - Credit goes to: Mostafa Azizi, Soroush Dalili - Link: http://sourceforge.net/projects/fckeditor/files/FCKeditor/ - Description: There is no validation on the extensions when FCKEditor 2.6.8 ASP version is dealing with the duplicate files. As a result, it is possible to bypass the protection and upload a file with any extension. - Reference: http://soroush.secproject.com/blog/2012/11/file-in-the-hole/ - Solution: Please check the provided reference or the vendor website. - PoC: http://www.youtube.com/v/1VpxlJ5jLO8?version=3&hl=en_US&rel=0&vq=hd720 Duplicate files do not have proper validation on their extensions. As a result, it is possible to upload any file with any extension on the server by using Null Character. Applications on IIS6 can also use "file.asp;gif" pattern. - Solution: In "config.asp", wherever you have: ConfigAllowedExtensions.Add "File","EXTENSION HERE" Change it to: ConfigAllowedExtensions.Add "File","^(Extensions HERE)$" - Vulnerability: Vulnerable File: commands.asp Function: FileUpload() Vulnerable Code: sFileName = RemoveExtension( sOriginalFileName ) & "(" & iCounter & ")." & sExtension Note: Quick patch for FCKEditor 2.6.8 File Upload Bypass: In “config.asp”, wherever you have: ConfigAllowedExtensions.Add “File”,”Extensions Here” Change it to: ConfigAllowedExtensions.Add “File”,”^(Extensions Here)$” |