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Category: Pentesting

A few new resources for pentesting/OSCP/CTFs

Here are a few new resources I’ve run across in the last month or so. I’ve gone back to add these to some of my older posts, such as the Windows Privesc Resources, so hopefully you’ll find them, one way or another.

Windows-Privilege-Escalation-Guide
https://www.absolomb.com/2018-01-26-Windows-Privilege-Escalation-Guide/

JSgen.py – bind and reverse shell JS code generator for SSJI in Node.js with filter bypass encodings
https://pentesterslife.blog/2018/06/28/jsgen/

So you want to be a security engineer?
https://medium.com/@niruragu/so-you-want-to-be-a-security-engineer-d8775976afb7

Local and Remote File Inclusion Cheat Sheet
https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/File%20Inclusion%20-%20Path%20Traversal

External XML Entity (XXE) Injection Payloads
https://gist.github.com/staaldraad/01415b990939494879b4

Enjoy!

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The Unofficial OSCP FAQ

It has been close to a year since I took the Penetration Testing with Kali (PWK) course and subsequently obtained the Offensive Security Certified Professional (OSCP) certification. Since then, I have been hanging out in a lot of Slack, Discord, and MatterMost chat rooms for security professionals and enthusiasts (not to mention various subreddits). When discussing the topic of obtaining the OSCP certfication, I have noticed *a lot* of prospective PWK/OSCP students asking the same questions, over and over.

The OffSec website itself covers some of the answers to some of these questions, but whether its because people don’t read it, or that it wasn’t made very clear, these questions keep coming back. Here, I will attempt to answer them as best I can.

Disclaimer: I am not an OffSec employee, nor do I make the claim that anything that follows is OffSec’s official opinion about the matter. These are my opinions; use them at your own risk.

  1. Do I have enough experience to attempt this?
  2. How much lab time should I buy?
  3. Can I use tool X on the exam?
  4. What note keeping app should I use?
  5. How do I format my reports?
  6. Is the HackTheBox.eu lab similar to the OSCP/PWK lab?
  7. Are VulnHub VM’s similar to the OSCP/PWK lab?
  8. What other resources can I use to help me prepare for the PWK course?

According to the official OffSec FAQ you do need some foundational skills before you attempt this course. You should certainly know your way around the Linux command line before diving in, and having a little bash or python scripting under your belt is recommended. That said, it’s more important that you can read code and understand what it is doing than being able to sit down and write something from scratch.

I see many people asking about work experience, which isn’t really covered by OffSec. For example, people wondering if 3 years of networking and/or 1 year being a SOC analyst is “enough.” These questions are impossible to quantify and just as impossible to answer. What you should focus on is your skills as they relate to what is needed for the course.

To do that, head over to the PWK Syllabus page and go through each section. Take notes about things that you are not sure about, or know that you lack skills and expertise in.

Once you have a list made, start your research and find ways to learn about what you need to get up to speed on. For example, when I was preparing for PWK, I knew very little about buffer overflows. I spent a while watching various YouTube videos, reading up on the methods by which you can use a buffer overflow exploit, and taking notes for future reference. Once I started the course, I was able to dive into the exercises and understand what was going on, at least a little bit beyond the very basics, which helped me save time.

In the same boat? Check out this excellent blog post about buffer overflows for something similar to what you will see in the PWK course. Also, while I haven’t tried it yet, I hear that this is a good buffer overflow challenge you can practice on.

Buy the 90 day course in order to get the most out of the experience and not feel crunched for time — especially if you work full time and/or have a family.

With 90 days, you can complete the exercises in the PWK courseware first, and still have plenty of time left for compromising lab machines.

I see this question a lot, perhaps more than any other. People want to know if it is safe to use a specific tool on the exam, such as Sn1per. The official exam guide from OffSec enumerates the types of tools that are restricted on the exam. It is pretty clear that you cannot use commercial tools or automated exploit tools. Keep this statement in mind when wondering if you can use a certain tool:

The primary objective of the OSCP exam is to evaluate your skills in identifying and exploiting vulnerabilities, not in automating the process.

If a tools helps you enumerate a system (nmap, nikto, dirbuster, e.g.), then it is OK to use.

If a tool automates the attacking and exploiting (sqlmap, Sn1per, *autopwn tools), then stay away from it.

Don’t forget the restrictions on Metasploit, too.

From what I have heard, even though OffSec states that they will not discuss anything about it further, people have successfully messaged the admins to ask about a certain tool and gotten replies. Try that if you are still unsure.

I wrote a lot about this already, so be sure to check out that write-up. In short, these are the main takeaways:

  • Do not use KeepNote (which is actually recommended in the PWK course), because it is no longer updated or maintained. People have lost their work because it has crashed on them.
  • CherryTree is an excellent replacement for KeepNote and is easily installed on the OffSec PWK Kali VM (it is bundled by default on the latest/greatest version of Kali).
  • OneNote covers all the bases you might need, is available via the web on your Kali box, and has clients for Mac and Windows.
  • Other options boil down to personal choice: Evernote, markdown, etc.

Check out the example reports that OffSec provides. From those, you can document your PWK exercises, your 10 lab machines (both of which contribute towards the 5 bonus points on the exam), and your exam notes.

I do not recommend skipping the exercise and 10 lab machine documentation, thus forfeiting your 5 extra exam points. I am a living example of someone who would not have passed the exam had I not provided that documentation. Yes, it is time consuming, but it prepares you for the exam documentation and helps you solidify what you have learned in the course.

There are definitely some worthy machine on Hack The Box (HTB) that can help you prepare for OSCP. The enumeration skills alone will help you work on the OSCP labs as you develop a methodology.

There are definitely some more “puzzle-ish” machines in HTB, similar to what you might find in a Capture The Flag event, but there are also plenty of OSCP-like boxes to be found. It is a good way to practice and prepare.

See the above answer about Hack The Box, as much of it applies to the VulnHub machines too. I used VulnHub to help me pre-study for OSCP, and it was a big help. The famous post by Abatchy about OSCP-like VulnHub VM’s is a great resource. My favorites were:

  • All the Kioptrix machines
  • SickOS
  • FrisitLeaks
  • Stapler

There are a lot of resources that can help you pre-study before you dive into the course. I will post some here.

Books

Online Guides

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Captured The Flag

Along with my friend eth3real (and some pitching in from our new friend Brian), we teamed up as DefCon828 and won the Capture the Flag contest at BSides Asheville today. The loot was some cool WiFi Pineapple gear.

Last month, Jess and I won 1st and 2nd place respectively at BlueRidgeCon. I do feel bad about missing out on the lectures, talks, and socialization at these awesome conferences, but I can’t stay away from the CTFs. It’s bad.

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What Note Taking App is Best for PWK and OSCP?

A very common question in OSCP student chat rooms and channels I hang out in is “should I be using something other than Keepnote?”

It is a fair question considering Keepnote is recommended in the PWK course materials. However, you may notice that it hasn’t been updated in over 6 years, and has actually been dropped from recent Kali versions. I have heard tales of OSCP students’ notes getting corrupted and lost, which is not a good situation to face when you are paying for limited time to complete the coursework (and exam).

If you are starting down the PWK/OSCP path, you will soon realize that you will need to take a lot of notes. Not just on the course materials, but on every exercise you do and every machine in the lab that you work on. This includes screenshots, copy-pasted output from nmap and other tools, and the specific steps you took to conquer a box (and hopefully the steps that didn’t work, from which you can reference in the future).

It adds up quickly, and it’s a challenge to keep straight as you hack away at box after box in the lab. Being a person that has kept a keen eye on note taking apps in general, long before I got my OSCP, I have some recommendations, with pros and cons of each.

In no particular order (see my Recommendations at the bottom):

CherryTree

Learn more and download CherryTree here.

The Good

  • Hierarchical (pretty much unlimited depth)
  • Free, open-source software for Linux and Windows. You *can* get this to run on a Mac, but it’s buggy
  • Highly customizable through preferences and templates
  • Imports notes from tons of places, does some good exporting too

The Bad

  • Can’t paste images from the clipboard directly into notes
  • Not the greatest at embedding files in general
  • Not easily synced between devices/VMs
  • No Mac or mobile device support

CherryTree is like KeepNote in many ways, but it is has many more features and is actively maintained. If you are going to be solely storing and referencing your notes on one machine (your host or Kali VM), use this tool. The template feature is really awesome, and it lets you create a new note based on a template of your design. This means you could create a template for Lab VMs that you can quickly populate with data as you work on a given machine. You could do something similar for PWK exercises. It should make reporting much easier.

Evernote

Download Evernote here.

The Good

  • Feature rich app, integrates with Web Clipper browser extension
  • Windows, Mac, iPhone, Android native clients with web version for Linux
  • Is modern and hip, if that matters to you

The Bad

  • Costs $ if you want it to be any good. Free features seem to be waning as they push people into paying for the service
  • Lacks true hierarchical organization (uses tags instead of folders)

My struggles with Evernote have been well documented on this blog in the past, but some people still swear by it, so I thought I’d mention it here. They do make ease-of-access a priority, and you can get to your Evernote stuff from just about anywhere. Using it is easy until you need to organize things with any complexity, and for the PWK labs, you’d have to be OK with using the #tags instead of folders.

Microsoft Onenote

Download Onenote from Microsoft here.

The Good

  • Feature rich app, integrates with Onenote Clipper browser extension
  • Free Windows, Mac, iPhone, Android native clients with web version for Linux
  • Free version is not feature limited (just space, which hasn’t been a problem for me)
  • Excellent hierarchical organization via notebooks > sections > pages > sub-pages

The Bad

  • Some people feel it has a bloated interface
  • Exporting notes can pose challenges with formatting if you stray outside the pre-made lines

After many trials and tribulations, I ended up going all-in with Onenote for PWK/OSCP, and life in general. The ability to create multiple, separate notebooks (and choose which ones you want to see on which devices) has been my favorite feature. I can separate work from life from projects from shared stuff this way, and I still have a good amount of hierarchical ability to organize things.

Your Favorite Markdown Editor

I see people profess their undying devotion to markdown when the note-taking discussion comes up in various OSCP forums/chats, and I respect their decision and desire for simplicity. However, the one feature I used most, and I can’t imagine living without in the OSCP course, is the ability to paste a screenshot into a note. I did this so much that it would have driven me crazy to have to do anything else, and with markdown, you have to do some form of “save image/reference image via text in the note/embed via some other mechanism”. There are extra steps involved, and you can’t easily do the copy/paste thing.

Clippers/Screenshot Tools

Speaking of screenshots and the need to embed them in your notes, there are several options I would recommend depending on your choice of note taking apps and the platforms upon which you use them. Here are my top three:

  • Snap ‘n Drag Pro (Mac only). Awesome customization options, ability to edit captures (add arrows/highlight/blurs), automatically adds to clipboard.
  • Skitch – If you use Evernote, use this (unless you are on a Mac, see above)
  • Shutter – Native Linux screenshot app

For PWK, I found the Evernote and Onenote clipper browser extensions to be limiting in that they only let you clip things from your web browser, when I needed to clip terminal output most frequently.

My Recommendations

Because I am primarily a Mac user, I need good support for screenshot pasting, and I prefer hierarchical note structure for organization, I went with Onenote and Snap ‘n Drag Pro for my PWK and OSCP work. I continue to use these two tools in my personal and professional life, too.

If I were not a Mac user, I’d go with CherryTree and Skitch.

Have any opinions or additional input about all of this? Let me know in the comments.

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Windows Privilege Escalation (privesc) Resources

I have obtained a standard user account on Windows. Now what?

This is a common question I see people inquire about frequently on the Discord/Slack/Mattermost servers I hang out on. This includes people working on CTF exercises (Hack the Box), OSCP/PWK studies, and just pentesting in general. The answer, of course, is that you need to enumerate the system and find a way to become Admin.

The methodology for how you actually do this depends on a lot, all depending on your specific environment and circumstances.

Windows Privilege Escalation to the Rescue

Here are some useful resources on what to do next in your given situation, after you have succesfully exploited your way onto a Windows box, but before you have the system administrator role. I collected these links, snippets, and exploits during my OSCP studies, saving them in this massive OneNote notebook. Rather than letting them sit there where no one but me can access them, I thought I’d share.

Some of these get pretty detailed, and some of them have links to yet even more resources on this topic.

Have fun…this rabbit hole runs deep!

Privesc Resources

Updated 11.11.18: A new resource I came across that looks pretty awesome:

Windows-Privilege-Escalation-Guide
https://www.absolomb.com/2018-01-26-Windows-Privilege-Escalation-Guide/

Elevating privileges by exploiting weak folder permissions
http://www.greyhathacker.net/?p=738/

Encyclopedia of Windows Privesc (video)
https://www.youtube.com/watch?v=kMG8IsCohHA&feature=youtu.be

Windows Privesc Fundamentals
http://www.fuzzysecurity.com/tutorials/16.html

Windows Privesc Cheatsheet
https://it-ovid.blogspot.com/2012/02/windows-privilege-escalation.html

Windows Privesc Check
A script that automates the checking of common vulnerabilities that can be exploited to escalate your privileges:
http://pentestmonkey.net/tools/windows-privesc-check

Common Windows Privesc Vectors
https://www.toshellandback.com/2015/11/24/ms-priv-esc/

Windows Post-Exploitation Command List
http://www.handgrep.se/repository/cheatsheets/postexploitation/WindowsPost-Exploitation.pdf

WCE and Mimikatz in Memory over Meterpreter
https://justinelze.wordpress.com/2013/03/25/wce-and-mimikatz-in-memory-over-meterpreter/

Windows Privesc – includes tips and more resource links, on Github
https://github.com/togie6/Windows-Privesc

Do you have any Windows Privesc resources you think should go here? Comment below and I will add them.

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Firefox Captive Portal Spam in Burp Suite

About a year ago, Mozilla added “captive portal” support to Firefox in an attempt to enhance usability when connecting to free WiFi portals, such as at an airport or a hotel. You have probably interacted with captive portals in the past, and if you are a Firefox user, you may have wondered why you had to open Chrome or IE or Safari to be able to log into the WiFi system, as you could only get the “Sign In” page to pop up in one of those browsers before getting access to the full Internet.

Firefox added support for these “Sign In” pages about a year ago, so that you don’t need to use a (shudder) different browser. That is all well and good, except for when it comes to using Burp Suite as a proxy for Firefox. If you are a pentester, you are probably used using Firefox (especially on Kali Linux) for your traffic proxying through Burp, as they make it easier than any other browser to set up and disable the proxy.

However, you may now be seeing a ton of requests like this:

Disable the detectportal.firefox.com requests

Seeing all those requests in Burp, much less thinking about all the noise they generate otherwise, is annoying. Because you probably won’t ever need to use a Captive Portal on your pentesting machine (a VM, in my case), you can completely disable Firefox’s attempts to detect them. Just browse to about:config and enter network.captive-portal-service.enabled. Double click it to change its value to “false” and you should be good to go.

That’s all, folks!

 

 

 

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