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Privacy, Cybersecurity, & Cloud

Demystifying Shamir’s Secret Sharing (SSS)

Posted on 19 Sep 2023 by Ray Heffer

Adi Shamir

Shamir’s Secret Sharing

For those of you interested in cybersecurity, or perhaps if you work in the field, you’ll face the massive topic of cryptography sooner or later. I wouldn’t call myself a cryptography expert by any means. The subject is vast, fascinating, and can be quite intimidating, especially with all the math involved! I prefer to learn complex topics by breaking them down into smaller parts, which, by the way, is the essence of Shamir’s Secret Sharing. Segmenting a topic into more manageable chunks makes it easier to grasp the concepts.

During my endeavor to expand my cryptography knowledge, I decided to write this post on Shamir’s Secret Sharing. Don’t worry, you don’t need a master’s degree in cryptography to grasp the essence of this brilliant algorithm. I’ll do my best to ensure you walk away from this blog post with a good understanding of its inner workings as well as its real-world applications!

I’ve also included some Python script here which you can use along with the example in the blog, to reconstruct the secret.

Tagged with: code cybersecurity security

The CISO Mindset Series

Posted on 07 May 2023 by Ray Heffer

In the ever-evolving world of cybersecurity, Chief Information Security Officers (CISOs) play a crucial role in safeguarding organizations against threats and ensuring compliance with various regulations. To help CISOs navigate the challenging cybersecurity landscape, I have put together a series of articles that delve into essential insights and best practices. Here I introduce to you, the CISO Mindset series.

As you saw in my previus blog post, I decided to leave Twitter, so I have been experimenting with sharing my insights on LinkedIn. So far I must say the engagement has proven to be far better! If you enjoy my posts, please consider following me and leaving a comment over on LinkedIn. Your feedback will encourage me to continue sharing more articles!

Tagged with: CISO cybersecurity security

003 - The Invisible Net, and Why I use GrapheneOS

Posted on 10 Apr 2023 by Ray Heffer

Welcome to episode three of The Lockdown - Practical Privacy and Security podcast.

This episode was recorded on March 9, 2023

Follow Ray on Twitter @rayheffer

Intro music: The Lockdown by Ray Heffer

The case of Zachary McCoy: https://12ft.io/proxy?q=https%3A%2F%2Fwww.westernjournal.com%2Finnocent-man-discovers-google-tracked-location-gave-info-police%2F

Tracking Phones, Google Is a Dragnet for the Police: https://www.nytimes.com/interactive/2019/04/13/us/google-location-tracking-police.html

Denmark frees 32 inmates over flaws in phone geolocation evidence: https://www.theguardian.com/world/2019/sep/12/denmark-frees-32-inmates-over-flawed-geolocation-revelations

This week’s episode:

  1. The case of Zachary McCoy
  2. Why do all this?
  3. The Apple Ecosystem
  4. My experience with GrapheneOS

“The rights of one are as sacred as the rights of a million.” - Eugene V. Debs

Tagged with: podcast security hackers cybersecurity

Changes to the OSCP (PEN-200) Exam for 2023

Posted on 16 Mar 2023 by Ray Heffer

I’m constantly seeking new opportunities to enhance my expertise and broaden my understanding in the field of cyber. In 2021, I successfully completed the Certified Ethical Hacker (CEH) exam offered by EC-Council, followed by the CISSP last year—both of which showcased diverse aspects of cybersecurity. In my day-to-day work, I collaborate with both security engineering teams and CISOs, as I hop from one meeting to the next, which requires me to transition between technical and strategic discussions. This skill has proven to be incredibly valuable in my career.

As someone who has always been deeply immersed in the technical aspects of cybersecurity, I find it essential to maintain and nurture that passion, even as I continue to evolve in my career. Participating in Capture The Flag (CTF) challenges during my evenings allows me to stay up to date with my hands-on skills. This is why I find the Offensive Security Certified Professional (OSCP) exam so appealing.

Tagged with: security hackers study oscp cybersecurity kali

OCSP Study Guide by Ray Heffer (K1LLSSF434)

Posted on 04 Feb 2023 by Ray Heffer

Note: Once the exam is finished, you will have a further 24 hours to upload your documentation.


Pass: 70/100 points to pass the exam

60 points: BOF (Buffer Overflow), 1 Easy, 1 Hard

  • 3 independent targets
  • 2-step targets (low and high privileges)
  • Buffer Overflow may (or may not) be included as a low-privilege attack vector
  • 20 points per machine
    • 10 points for low-privilege
    • 10 points for privilege escalation

40 points: Active Directory Set

  • 2 clients
  • 1 domain controller
  • Points are awarded only for the full exploit chain of the domain
  • No partial points will be awarded

Study Resources

Thanks to TJ Null, for this awesome list of Hack The Box an Proving Grounds OSCP like machines to practice with. The first link below for his blog outlines OSCP boxes for both Proving Grounds and HTB, plus there is an updated HTB list by Rana Khalil, so thanks also to Rana!

Getting Started

Here is the order that I’d recommend based on other people experiences with the OSCP exam. Start with TryHackMe, especially if you are new to this. TryHackMe will be a much easier point of entry for beginners. Then, when you are more comfortable with Kali Linux and have the basics down, move on to the rest on this list.

  1. TryHackMe Premium Membership for $72/year (first year)
  2. Udemy courses (see below) and / or PEN-200 course included with the exam options in step 4.
  3. Get HTB VIP $203/year: https://app.hackthebox.com/vip
    1. and/or Proving Grounds Practice $199/year: https://www.offensive-security.com/labs/individual/
  4. Exam options
    1. Get the PEN-200 course and certification bundle $1599/year which includes the exam and 90 days PG Practice access.
    2. Get Learn One $2499/year which includes the exam and 1 year PG Practice access.

Udemy OSCP Courses

Create a new Udemy account for each course to get the discounts, otherwise if you use an existing account you’ll end up paying full price.

Blogs & Articles

Exam Tips

  1. You MUST own the Active Directory part, this gives you 40 points since no partial points are awarded here. This is a GOOD thing! Know how to do this, and the rest will be easier.
  2. Learn pivoting
  3. Do all TryHackMe rooms for Active Directory
  4. Do the THM rooms by Tib3rius
    1. Buffer Overflow
    2. Windows Privilege Escalation (part of Windows Privilege Escalation for OSCP & Beyond!)
    3. Linux Privilege Escalation (part of Linux Privilege Escalation for OSCP & Beyond!)
  5. Learn how to compile C programs (gcc), which many exploits will require.
    1. Compiling and Running C++ Applications Separately
  6. Make awesome notes, and post write-ups. If you can’t explain it simply, then you are winging it. I use Obsidian, since I write in Markdown and like how it simply creates directories and files, not some proprietary nonsense.

Exam Restrictions

You cannot use any of the following on the exam:

  • Spoofing (IP, ARP, DNS, NBNS, etc)
  • Commercial tools or services (Metasploit Pro, Burp Pro, etc.)
  • Automatic exploitation tools (e.g. db_autopwn, browser_autopwn, SQLmap, SQLninja etc.)
  • Mass vulnerability scanners (e.g. Nessus, NeXpose, OpenVAS, Canvas, Core Impact, SAINT, etc.)
  • AI Chatbots (e.g. ChatGPT, YouChat, etc.)
  • Features in other tools that utilize either forbidden or restricted exam limitations

Tagged with: security hackers study oscp cybersecurity kali

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