[tor-dev] Project "Cute" - Design document and challenges - draft

SiNA Rabbani sina at redteam.io
Tue Oct 8 09:31:11 UTC 2013

Dear Team,

Sorry for multiple emails, I failed to send to tor-dev@ properly.
Here is an attempt, a first attempt at the "Cute" project. 
Please let me have your comments and suggestions.


All the best,


"Cute" design and challenges - draft 0.1
By: SiNA Rabbani - sina redteam io


Project Cute is part of the Otter contract. This project is to provide 
(in the parlance of our time) "point-click-publish" hidden services to support 
more effective documenting and analysis of information and evidence documenting 
of ongoing human rights violations and corresponding training and advocacy Our 
goal is to improve hidden services so that they're more awesome, and to create 
a packaged hidden-service blogging platform which is easy for users to run.


To make secure publishing available to activists who are not IT professionals.


Tor offers Hidden Services, the ability to host web sites in the Tor Network. 
Deploying hidden services successfully requires the ability to configure a 
server securely. Mistakes in setup can be used to unmask site admins and the 
location of the server. Automating this process will reduce user error.
We have to write "point-click-publish" plugins that work with existing blogging 
and micro-blogging software.

*Expected results*

The result will be a way to provide portals to submit text, pictures, and video. 
These sites will not have the ability to log information that can be used to 
track down citizen journalists or other users, and will be resistant to 
distributed denial of service (DDoS) attacks.



This document describes the technical risks associated with running a web-based
blog tool and exposing it over a hidden service (.onion address). Our goal is to
create a packaged blogging platform that is easy to operate for the 
non-technical user, while protecting the application from a set of known attacks
that can reveal and compromise the network identity.

Hidden-services make it possible for content providers and citizen 
journalists to offer web-applications such as blogs and websites, hosted 
completely behind a firewall (NAT Network) never revealing the public IP of such
services. By design, Hidden Services are resilient to attacks such as traffic 
analysis and DDoS, therefore it becomes compelling for the adversary to focus 
on the application layer vulnerabilities. 

According to OWASP Top 10, Injection is the number one security risk for 
web applications. "Injection flaws, such as SQL, OS, and LDAP injection occur 
when untrusted data is sent to an interpreter as part of a command or query. 
The attacker?s hostile data can trick the interpreter into executing 
unintended commands or accessing data without proper authorization." [1]

Running a site such as WordPress involves a LAMP (Linux, Apache, Mysql, PHP)
installation. This stack needs to be carefully configured and implemented to 
meet the desired privacy and security requirements. However, default 
configuration files are not suitable for privacy and lead to the leakage of 

WordPress is the most popular blog platform on the Internet. We select WordPress
due to it's popular and active core development. WordPress features a plug-in 
architecture and a template system, "Plugins can extend WordPress 
to do almost anything you can imagine. In the directory you 
can find, download, rate, and comment on all the best plugins  the 
WordPress community has to offer." http://wordpress.org/plugins/

Themes and plugins are mostly developed by programmers with little or no 
security in mind. New code is easily added to the site without the need for any 
programming skills. This is recipe for disaster, a quick look at the publicly 
available plugin repository and security forums reveals many of the OWASP top 10 
vulnerabilities such as XSS and injection vulnerabilities:



*Adversary Model*

We use the range of attacks available to the adversary adversary as the base for
our Threat Model and proposed requirements.

*Adversary Goals*

	*Code Injection*
	This is the most direct compromise that can take place; the ability for 
	the adversary to execute code on the host machine is disastrous.

	*XSS the front-end, DoS the back-end*
	The adversary can overwhelm the database backed or the web-server of a 
	dynamically hosted application, denying access to the service.

	*Location/Identity information*
	Applications that are not designed with privacy in mind tend to reveal 
	information by default. For example, WordPress includes the name of the 
	editor of a post inside the RSS feed: <dc:creator>John Smith</dc:creator>

*Adversary Capabilities - Positioning*

The adversary can position themselves at a number of places to execute their 

	*Local Network/ISP/Upstream Provider*
	The attacker can hijack the DNS of the plugin repository or perform a 
	man-in-the-middle attack and push malicious code into the blog. 
	*Third party service providers*
	It is common for a blog to email authentication information. 
	This information is at risk of social and legal attacks. 
	The repository of the blog's source code where themes and plugins are 
	downloaded is a target for the adversary to insert malicious code.

*Adversary Capabilities - Attacks*

The adversary can perform the following attacks in order to accomplish varies 
aspects of their goals. Most of these attacks are due to the dynamic and 
Web 2.0 nature of blog platforms. 

	*SQL Injection & XSS*
	Dynamic sites take advantage of databases for content storage and 
	JavaSript for client-side presentation. Programming mistakes can lead to
	code injection on server or client side.

	*Inserting plugins or core updates*
	Blog platforms have automatic update install features, WordPress 
	connects to a remote repositories to download updated code. 
	Adversary can perform a man-in-the-middle attack and insert malicious

	*Misbehaving plugins/features*
	Some plugins depend on remote connections to provide a feature, 
	for e which can lead to leakage of identity.

	*Brute-force the admin password*
	Weak passwords are vulnerable to brute-force attacks. 
	Blog engines do not provide protection against such attacks.

	*Remotely exploiting the LAMP stack*
	A determined adversary has a very large attack surface to analyze 
	and discover 0-day vulnerabilities in Apache, PHP or Mysql applications.


*Proposed requirement*

	*Dynamic to Static*
	A simple yet effective way to protect dynamic websites is to save a 100% 
	static copy, hosted with a lightweight and well configured http server. 
	We propose Nginx which is a free, open-source, high-performance 
	HTTP server. We have the option of extending existing WordPress plugins 
	such as "Really-Static" (HTTP://word press.or/plugins/really-static/) to 
	generate 100% static files.

	*Disable Comments and New User signup (POST REQUESTS)*
	The ability to receive and store comments involves actions and 
	configurations that expose the installation to DoS and other web attacks.
	We propose to completely disable reader's backed interactions,
	specifically disabling New User Registration and Comment features.

	*SOCKS Proxy support for WordPress*
	WordPress has the ability to proxy its outgoing connections, however the
	current implementation only supports HTTP proxy. We propose to submit a 
	patch to WordPress core, enabling SOCKS Proxy support:

	*Update safety*
	Tor Project or a partner such as WordPress.org should maintain the latest 
	copy of the WordPress source-code over a .onion address. This will allow
	for the Core application updates to take place without ever leaving the 
	Tor network and we achieve end-to-end encryption without relying on the 
	traditional SSL/CA model.

	*OnionPress plugin*
	Instead of hard-coding our modifications to control WordPress' 
	functionalities, we propose to develop a custom plugin. 
	The plugin will provide	a new menu in the Administrative panel of the 
	site. Providing options to interact with Hidden Service features.
	(Note that Administrative features are going to be restricted from 
	the public and only available to localhost)

	*User Authentication/Permission Levels*

		a) Blog Administrator
		This person is hosting the blog on a local computer and has physical 
		access to the installation. There is only 1 of such role. This 
		login will be restricted to localhost only.

		b) Blog editors/contributors
		These are the active content publishers. Each person has the ability
		to remotely connect, login and publish content. Editors do not have
		any administrative permissions such as adding or deleting users.
		Each editor is assigned a dedicated key and .onion hostname using 
		the HidServAuth and HiddenServiceAuthorizeClient features in 
		stealth mode. 

		"HiddenServiceAuthorizeClient auth-type client-name,client-name,…
		If configured, the hidden service is accessible for authorized 
		clients only. The auth-type can either be 'basic' for a 
		general-purpose authorization protocol or 'stealth' for a less
		scalable protocol that also hides service activity from 
		unauthorized clients. Only clients that are listed here are
		authorized to access the hidden service. Valid client names 
		are 1 to 19 characters long and only use characters in 
		A-Za-z0-9+-_ (no spaces). If this option is set, the hidden 
		service is not accessible for clients without authorization 
		any more. Generated authorization data can be found in the 
		hostname file. Clients need to 	put this authorization data 
		in their configuration file using HidServAuth."
		c) Readers (the world)
		These are the site visitors, they will be able to send GET requests
		to the .onion address and receive HTML and multimedia content.
		No login or comment posting permissions granted.

	*Packaged System*

	We propose to design and develop a Debian based Live OS that can 
	be started as a Virtual Machine or to boot a personal computer. This OS
	will include Tor, LAMP stack and a running copy of WordPress.

	The LAMP installation will be hardened and configured to meet our
	security desires. We require a secondary USB disk for persistent storage. 
	Desired outcome is a point-and-click and maybe portable solution that 
	can be launched from inside of Windows, Linux or Mac OSX.
	VirtualBox is a second candidate to host the VM.
	http://wiki.qemu.org/Main_Page and/or https://www.virtualbox.org/

	*Edge Cache Nodes*

	In order to provide "blazing-fast" access to the published content
	outside of the Tor network, we propose the deployment of caching servers
	operated by semi-trusted third party organizations or persons. These are
	similar to tor2web nodes:http://tor2web.or/

	The content providers (bloggers) would select from a list of available 
	edge servers and send a pgp signed zip file of the latest static version 
	over Tor. Edge servers will reduce traffic from the Tor network, also 
	provide a chance for content to reach the world in case of a DDoS or 
	technical issues with the Tor network itself.
	Having cached copies available remotely make it possible for the blogger
	to get on-line, publish content and go back off-line, minimizing the 
	amount of time and traffic spent on the Internet.


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