Remote code execution via CSRF vulnerability in the web UI of Deluge 1.3.13 Kyle Neideck, February 2017 Product ------- Deluge is a BitTorrent client available from http://deluge-torrent.org. Fix --- Fixed in the (public) source code, but not in binary releases yet. See http://git.deluge-torrent.org/deluge/commit/?h=develop&id=11e8957deaf0c76fdfbac62d99c8b6c61cfdddf9 and http://git.deluge-torrent.org/deluge/commit/?h=1.3-stable&id=318ab179865e0707d7945edc3a13a464a108d583 Install from source or use the web UI from an incognito/private window until new binaries are released. Summary ------- Deluge version 1.3.13 is vulnerable to cross-site request forgery in the Web UI plug-in resulting in remote code execution. Requests made to the /json endpoint are not checked for CSRF. See the "render" function of the "JSON" class in deluge/ui/web/json_api.py. The Web UI plug-in is installed, but not enabled, by default. If the user has enabled the Web UI plug-in and logged into it, a malicious web page can use forged requests to make Deluge download and install a Deluge plug-in provided by the attacker. The plug-in can then execute arbitrary code as the user running Deluge (usually the local user account). Timeline -------- 2017-03-01 Disclosed the vulnerability to Calum Lind (Cas) of Deluge Team 2017-03-01 Vulnerability fixed by Calum Lind 2017-03-05 Advisory released To Reproduce ------------ - Create/find a Deluge plug-in to be installed on the victim machine. For example, create an empty plug-in with python deluge/scripts/create_plugin.py --name malicious --basepath . \ --author-name "n" --author-email "e" (see http://git.deluge-torrent.org/deluge/tree/deluge/scripts/create_plugin.py?h=1.3-stable&id=318ab179865e0707d7945edc3a13a464a108d583) and add a line to its __init__.py to launch calc.exe. - Build the plug-in as a .egg (if necessary): python malicious/setup.py bdist_egg - Make a torrent containing the .egg and seed it somewhere. - Create a Magnet link for the torrent. - In the proof-of-concept page below, update the PLUGIN_NAME, PLUGIN_FILE and MAGNET_LINK constants. - Put the PoC on a web server somewhere. Serving it locally is fine. - In Deluge, open Preferences, go to the Plugins category and enable the Web UI plug-in. - Go to the WebUi preferences section and check "Enable web interface". The port should be set to 8112 by default. - If you're serving the PoC over HTTPS, check "Enable SSL" so its requests don't get blocked as mixed content. If you're not, SSL can be enabled or disabled. - Go to localhost:8112 in a browser on the victim machine and log in. - Open the PoC in the same browser. The PoC sends requests to localhost:8112 that include cookies. The first request adds the torrent, which downloads the .egg (the plug-in) to /tmp. It then sends repeated requests to install the .egg and enable it. The attacker's code in the plug-in runs when the plug-in is enabled. For the attack to be successful, the PoC page must be left open until the malicious plug-in finishes downloading. An attacker could avoid that limitation by using the Execute plug-in, which is installed by default, but Deluge has to be restarted before the Execute plug-in can be used. I don't think that can be done from the web UI, so the attacker's code would only execute after the victim restarted Deluge and then added/removed/completed a torrent. The PoC adds the plug-in torrent using a Magnet link because it would need to read the web UI's responses to add a .torrent file, which CORS prevents. Proof of Concept ---------------- # Iranian Exploit DataBase = http://IeDb.Ir [2017-03-07]