File Upload Vulnerability Advanced Attack Techniques PART2-1: File Upload Library Analysis and Attack Methodology

File upload vulnerabilities, advanced techniques!
We deliver the essential information that you won't find anywhere else.

File Upload Vulnerability Attack Lecture
Finally, the last part of the series!

📖 A series of file upload vulnerability attacks explained by a mock hacking practitioner

File Upload Vulnerability Attack Techniques and Practical Case Analysis: PART 2

The final part of our lecture on file upload vulnerabilities!
This lecture is the sequel to the lecture titled 'Part 2', 'File Upload Vulnerability Attack Techniques and Practical Case Analysis by a Simulated Hacking Practitioner: PART 1' .

File Upload Vulnerability Attack Part 2 is divided into three parts , and each topic is as follows.

Part 2-1 Current Lecture

File Upload Library Analysis and Attack Methodology

Part 2-2

Basic knowledge and techniques for bypassing web firewalls

Part 2-3

Attack methodologies in various practical environments

This lecture is Part 1 of Part 2, and covers the topic of 'File Upload Library Analysis and Attack Methodology' .

Something you can't hear anywhere else
I included it in the lecture!

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There are many ways to learn web hacking today. Most of the common ones, such as online lecture platforms like Inflearn, offline lectures at academies, and search engines, tend to focus on general content.

But this lecture is different. We are proud to say that it is 'content you can't hear anywhere else!'

File Upload Vulnerability Attack Part 2-1
Check out what you'll learn!

💡 This lecture is Part 1 of Part 2 , and covers 'File Upload Library Analysis and Attack Methodology' .

Upload verification logic known to be safe, but is it really safe?

The source code below is known to be safe from file upload vulnerabilities. So is it really safe?

 ... String path = request.getRealPath("/upload"); MultipartRequest multi = new MultipartRequest(request, path, 1024*10*10, "UTF-8"); Enumeration formNames = multi.getFileNames(); while(formNames.hasMoreElements()) { String param = (String)formNames.nextElement(); String uploadFile = multi.getFilesystemName(param); int extOffset = uploadFile.lastIndexOf("."); String fileExt = uploadFile.substring(extOffset+1).toLowerCase(); if (!fileExt.equals("jpg") && !fileExt.equals("png") && !fileExt.equals("gif")) { File fp = new File(path, uploadFile); fp.delete(); out.println(“ "); return; } } ...<script> alert(‘잘못된 확장자’);history.back(-1);</script> ... String path = request.getRealPath("/upload"); MultipartRequest multi = new MultipartRequest(request, path, 1024*10*10, "UTF-8"); Enumeration formNames = multi.getFileNames(); while(formNames.hasMoreElements()) { String param = (String)formNames.nextElement(); String uploadFile = multi.getFilesystemName(param); int extOffset = uploadFile.lastIndexOf("."); String fileExt = uploadFile.substring(extOffset+1).toLowerCase(); if (!fileExt.equals("jpg") && !fileExt.equals("png") && !fileExt.equals("gif")) { File fp = new File(path, uploadFile); fp.delete(); out.println(“ "); return; } } ...

No , the source code is 'vulnerable' .
Why this code is vulnerable and how to exploit it are covered in detail in lecture Part 2-1.

Want to know more? 📚

This is not a lecture that tells you the correct answer.
This is a lecture that will broaden your perspective!

'File Upload Vulnerability Part 2' consists of three lectures to successfully attack file upload vulnerabilities in various environments. However, this is not a lecture that gives you the right answers. Taking this lecture does not mean that you will successfully attack file upload vulnerabilities in all environments.

The goal of this lecture is not to give you the right answer, but to broaden your perspective . If you learn that vulnerabilities can occur in various environments, you will gain the enlightenment of 'Oh, I can try this too!', and furthermore, you will be able to 'know' and analyze various environments in future diagnoses. There is a world of difference between knowing and analyzing this and analyzing without knowing.

I hope that this lecture will give you a solid perspective on web hacking and lay the foundation for taking your skills to a higher level!

Expected Questions Q&A 💬

Things to note before taking the class 📢

We recommend that you take this course with an understanding of web technology and web hacking. We also recommend that you first take the lectures ‘File Download Vulnerability Attack’ and ‘File Upload Vulnerability Attack Part 1’ from Creative’s web hacking lecture series.

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