OSED Done
OSED is tough, it can make you cry.
I will be sharing my personal experience and opinion about the course and exam in this writing.
What is OSED
OSED is one of the certification provided by Offsec. OSED certification is obtained after passing a practical exam of 72 Hours and exam preparation is done by going through course Exp-301 ( Exploit Development ) provided by Offsec - this course teaches you exploit development.
In field of exploit development / vulnerability research and reverse engineering you will not find so many certifications offering you courses and exam, and if there are at least 2 or 3 available, in my opinion Offsec has the best reputation and content available on this subject.
Since the OSCP gained massive attention in the past 10 years , OffSec certification was on my list. Anyways this year I was able to dedicate some time, and as per my skill I chose OSED certification.
Pre-Requisite for starting with OSED
According to Offsec official site, there is no education / certification or formal requirement to purchase and start OSED, that means you don’t need a OSCP or any other certification to start the EXP-301 course.
However since this course is highly technical, you are expected to have following for best outcome,
- Familiarity with debuggers (ImmunityDBG, OllyDBG, WinDBG).
- Familiarity with basic exploitation concepts on 32-bit.
- Familiarity with writing Python3 code.
As per EXP-301 syllabus Offsec will be teaching 32 bit Windows Userland exploit development and vulnerability research. Those who hold OSED certification have the skill and expertise neessary to write their own shellcode and create cusomt exploits from scratch. They can use these exploits to reverse-engineer bugs and bypass common Windows security mitigation.
This requires you to have understanding of assembly language ( at least 32 bit ), understand system organization , program memory ( stack, memory, heap ), able to script in python to make your own automation, good understanding of computer networking.
I suggest that you should have solved some CTFs for 32 bit which requires to run a debugger , reverse engineer a binary , maybe exploit it or patch it.
During my days I was interested in these topics and I have studied Vivek Ramchandran’s Assembly language primer, pwnable.kr (Toddler’s Bottle) challenge , Overthewire Narnia challenge
By doing these you should have good understanding of vanilla stack overflow ( actually I have heard OSCP ends here when you perform vanilla stack overflow on a simple 32 bit binary)
My practice of all these concepts were only on linux, you can have anything either windows or linux.
Actually before this course I have never debugged or reversed a GUI binary neither on linux nor on windows, if you can do some GUI based binary debugging as well would be a plus.
And the time came when I thought I should not postpone this but accept the challenge with what I have as learning, and I started the course.
To start the course you have to buy the EXP-301 course bundle.
Packages offered by Offsec
There are two popular ways you can enroll for the course and exam
Cert bundle with 3 months access
So you will get access to the course for 3 months and then 1 attempt to pass the exam.
After you exhaust your time you can pay more to get more time to access the course or pay more to get more exam attempts.Learn One - learn one allows you to access the course content for 1 year and allows you to give 2 exam attempts.
Due to limited hours I had with my job and personal life, I also felt my pre-requisite preparation was not that good - I decided to go for learn One bundle.
I also saved some money in case I fail in both of the attempts, so I can purchase a third attempt. But thankfully that was not the case. I was able to pass the exam in my first attempt.
You can check more at the official web page here.
Let’s start the hustle
I purchased the course and started learning, I tried video and textual content both and later what worked for me was textual content. Offsec recommends to go through text and videos both, IMO I was ready after going through text content only along with all possible labs.
The OffSec learning portal is really good. At start you will get a VPN pack, to access the labs inside your course content.
So there are 2 kind of labs included in your course bundle, the lab which you will do along side your course topics for practicing what you have learnt, the other one is the final challenge lab (mock) - when you think you have completed the course and want to test your knowledge there are 3 challenges available at the end of course which you can practice - my final exam was similar to these 3 challenges (Please note your exam may vary)
First thing you should do is join their discord channel when your course starts, there you can raise a support request in case your VPN doesn’t work or any other kind of technical problems.
There you can read what your fellow students are talking about. One thing I would highly suggest is not to connect to your fellow students for sharing solutions of labs or asking them what comes in exam etc.
Because that might give you some insight on things and help you in exam, but it will completely defeat the purpose of learning - it’s okay to fail , you will learn more, definitely.
But try to pursue the course with pure intent to understand it, brainstorm the topics, study it, take breaks, repeat. If something doesn’t make sense do not jump the topic but take a step back and only if you have tried all the ways seek help from student mentors in Discord group.
Avoid AI while learning - try old school method of study, go to documentation read those, understand those. RTFM.
AI during the learning phase will make you very weak. Once you have mastered the topics, conquered the exam, then use AI to its full potential to boost your research but during the learning phase stay away, there are a whole bunch of guidelines for AI usage during exam by Offsec.
Read every chapter - every topic - do every lab - every extramile lab and then complete your 3 challenges after the course. Do all these without external help without any shortcuts.
If you have done all of these you are ready for the exam.
You will need to schedule your exam before attempting it. The practical exam will go on for 47 Hours 45 Minutes and the moment you complete your exam, the next 24 hours will be for report writing. Believe me even if 24 Hrs sounds like a large buffer for writing the report - it’s not. I was under a severe time crunch while writing the exam report.
Read the exam guide very very carefully before starting your exam.
The same exam guide also mentions The OSED certification exam is comprised of three independent tasks related to exploit development that must be solved.
And also The exam consists of three tasks, which will test the topics covered in the syllabus, including reverse engineering to discover vulnerabilities, crafting exploits that bypass security mitigations and creating custom shellcode.
2 Important things you should have get ready before you start your exam,
- Prepare your notes while studying the topics - these notes will be your go-to thing when you are in exam. In my case I avoided making notes and which really was a bad decision and 2 3 days before the exam I searched the internet for OSED notes and used one of them - only downside was notes organization was not as per me and those shortcut immediately doesn’t make sense. But if it would have been my own notes I would have known it page by page.
Please make your own notes and optimize them before the exam. - Exam report format - there are plenty options available - the one suggested by offsec themselves and other are more formatted with more colors. You are free to create your own until it follows the Documentation Requirements provided in exam guidelines. Whatever format you finalize make yourself comfortable with it - so while in exam you can paste raw notes to complete the final report sooner. I struggled alot here because I went unprepared for reporting and it almost got me thinking that I might fail the exam just because of my report.
Exam
I cannot write in words the pressure, and fear of failure I had during the exam. The exam was hard - no doubt in it. I prepared to give the best of me.
There were 3 independent challenges in the exam which will test your knowledge you gained during the course. And yes this is a proctored exam.
After completing my background verification steps I was ready for the exam.
I took around 10 hours (including breaks) to complete the first assignment and the next 1 to 2 hours to capture all the screenshots.
Then I attempted the hardest challenge which had multiple sub parts to it - I took around 24 hours to complete this task and next 2 hours to take all important screenshots.
I was too tired at this point of time - I decided to take a short break of 1 hour.
Then I attempted the final remaining challenge I knew this will not take time but I will need to read a lot of APIs for this. In like next 5 hours I was able to complete this one as well and next hour for screenshot. At this point I couldnt hold it I have to goto sleep - I tried to go for at least 4 to 6 hours but I couldnt, because I have to prepare this exam report.
Exam report has to be very detailed and well explained.
During all this time I took many short breaks every hour or two - breaks on every small wins.
Till this point of time I should have taken a nice sleep and my exam template should be ready but I literally messed up both the things which costed me extra pressure and sleeplessness.
However I was able to complete my report just in time 1 hour before the report deadline.
And I wish I had more time to correct the sentences check for grammar - polish it but I couldnt and I submitted what I had.
I think within 5 to 6 days I received the good news that I have passed the exam and that waiting time was seriously a pain.
But when the exam result came I was very happy, very excited, and felt really proud. The long awaited dream has come true.
I honestly believe I could not have alone did this, it was true blessings from those who love me.
And I am really excited to share this news with you all, also now I will try to put more reverse engineering content here frequently.
Few things worth mentioning
- This course teaches you 32-bit reverse engineering and exploit development, and in this era (2026) the knowledge might not be very much useful if implemented directly
Right now Windows have more advanced security mitigations, x64 and ARM are widely used instead of 32-bit, memory corruption vulnerability as simple as buffer overflow might be hard to find - but you have to start learning at some point - it might be difficult for someone to learn those advanced topics directly without going through the topics and concepts EXP-301 course material offers.
In my opinion this was really a good starting point for reverse engineers, vulnerability researchers, but one should not assume OSED alone will make them excellent reverse engineer / vulnerability researcher, to reach there you have to take this knowledge to the next level by a lot of practice. - Avoid contacting people who are preparing for the exam, or those who have completed the exam for the sole purpose of getting to know what was there inside the exam and how to complete them with shortcuts. By doing this you will be wasting your own time , preloaded with assumptions (of someone else) - the course content and labs are more than enough to get you prepared.
- Prepare your notes - optimize them, no extra tools or scripts are required to pass the exam - just use what is present in course material.