After months of preparation and hands-on practice, I am thrilled to share that I have officially passed the Offensive Security Experienced Penetration Tester (OSEP) exam! This journey has been both challenging and rewarding, pushing my skills in advanced penetration testing, Active Directory exploitation, and antivirus evasion to new heights.
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Why OSEP?
The OSEP certification, offered through the PEN-300 course, is designed by OffSec as the next step after the OSCP for those looking to advance their expertise in penetration testing. Unlike the OSCP, which focuses on foundational penetration testing techniques, the OSEP delves deeper into bypassing modern security mechanisms, advanced lateral movement, and post-exploitation strategies within complex enterprise environments.
In today’s cybersecurity landscape, where EDR (Endpoint Detection and Response) solutions, Windows Defender, and security hardening have made traditional attack techniques less effective, mastering modern evasion tactics is essential for any penetration tester or red teamer. The OSEP course provided me with the tools and methodologies to tackle these challenges head-on.
Course and Labs Experience
The PEN-300 course covers two major areas:
- Client-Side Code Execution: Techniques such as Office Macros, JScript, HTA files, and network filter bypasses for obtaining initial access. While some of these methods are becoming obsolete in modern environments, understanding their evolution and alternatives was insightful.
- Advanced Network Penetration Testing: A deep dive into Active Directory exploitation, lateral movement, credential attacks, and post-exploitation techniques in Windows and Linux environments.
The course materials, available in both text and video formats, were well-structured. However, what truly helped solidify my learning were the seven challenge labs. These labs simulated real-world enterprise environments, providing an invaluable hands-on experience in bypassing security controls and compromising networks.
One key takeaway from my preparation was that practicing multiple evasion techniques is crucial. The default techniques taught in the course often trigger modern security solutions, so I spent additional time refining custom payloads and testing in different environments.
The Exam Experience
The OSEP exam is a 48-hour simulated penetration test in a large, multi-domain network. It requires a methodical approach to gain initial access, pivot within the environment, and ultimately compromise the domain controller. My strategy involved:
- Taking structured breaks to stay focused and avoid fatigue.
- Documenting every step meticulously to streamline the reporting process.
- Triple-checking my flags and screenshots before submission.
While the exam environment was stable, there were definitely a few twists that tested my adaptability. Certain payloads that worked in labs didn’t perform as expected, forcing me to troubleshoot and modify my approach on the fly. By the end of the test, I was able to get more than enough flags to pass the exam, but I couldn’t read the secret.txt file via a reverse shell. I believe I was very close-perhaps just one trick away from being able to read it. However, the flags, my methodology and thorough documentation ensured a passing result. It’s very important to document everything thoroughly in your report.
Post-Exam Reflections
The OSEP certification was a fantastic learning experience, but it also highlighted some areas where the course material could be modernized. Some attack techniques (like Office Macros and JScript exploits) are becoming less relevant due to security advancements, while modern tactics involving LNK, PDF, and HTML file exploits aren’t covered in-depth. Additionally, operational security (OpSec) and detection evasion strategies could be better integrated into the course to make it more reflective of real-world engagements.
That said, the OSEP remains an excellent certification for penetration testers, red teamers, and even blue teamers looking to enhance their offensive security knowledge. The focus on Active Directory and enterprise security bypasses makes it particularly valuable for those working in corporate penetration testing or adversary simulation.
Final Thoughts and Next Steps
Passing the OSEP was a challenging yet fulfilling experience that strengthened my technical expertise, problem-solving skills, and resilience under time constraints. If you’re considering the OSEP, my advice is:
- Master the labs-do them multiple times with different approaches. Do the challenges as well.
- Automate everything you can– Everything that is taught in the course, have a C#/PS or python script ready for it.You just change the shellcode.
- Focus on OpSec-stealth is just as important as exploitation.
- Use a solid reporting tool-whatever you’re comfortable with (notepad, evernote, obsidian etc)
- Thorough Reporting – Focus on the report, don’t skip steps. Add screenshots, commands, custom scripts etc.
- Speed – There’s no time to waste. there’s a lot of stuff to do/try. Make sure you understand everything and you have everything in place & ready to go.
- Callbacks first – Don’t send your fully weaponized Word first, see if you can get a HTTP callback first. Always monitor your HTTP logs for callbacks
- Port Forwarding – You need to master it, with both MSF & Chisel
- Shellcode – Never in clear text. This is obvious, but it actually happened to me once, hence why I thought I should mention it 😀
With this milestone achieved, I’m now looking ahead to further red teaming and adversary emulation certifications. Cybersecurity is an ever-evolving field, and staying ahead means constantly learning and adapting.
On to the next challenge!
More Exam Reviews
If you’re interested in my experiences with other red team certifications, I’ve also written reviews on:
Feel free to check them out if you’re considering those certifications!
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