Problem creating ISO from bootable USB drive

[mdj2000]

Good morning to the whole community.

I'm trying to understand where is the mistake I'm making even though I have dozens of tests without a correct result, that is, I can't boot the ISO created from a bootable USB pen drive.
Premise
I downloaded Kaspersky Rescue Disk. The file is an ISO. I install the ISO on the pen drive through RUFUS. The pen drive is bootable and its operation is correct (tested on PC after bios post and before the operating system).
Problem
How do I get the reverse process now? That is, through imgburn I want to create a bootable ISO starting from the pen drive.
Resolution (currently unsolved).
Obviously I start the ImgBurn program, click on creating a new image from files/folders.
I select the source letter of the pen drive, select the advanced tab, then select the bootable disk tab.
I activate the make a bootable disk flag
Now I tried to extract the boot image and insert it into the boot image.
Start the creation of the ISO but the newly created file is not bootable (tested with a virtual machine) while the original ISO works correctly (again tested with a virtual machine).

I also tried looking for a boot image from the disk, but I can't figure out which file to select and if there is any other flag or value I need to set

This helps me understand which are the correct settings I need to use. The problem is that some programs allow you to directly create a bootable USB pen drive without the possibility of having an ISO to manage instead.

Where is the error? Thank you

[dbminter]

Unfortunately, I never got a successful bootable ISO to ever be created by ImgBurn's Build mode.

[mdj2000]

1 hour ago, dbminter said:

Unfortunately, I never got a successful bootable ISO to ever be created by ImgBurn's Build mode.

just out of curiosity: if you succeeded with some other tool, what did you use? Thank you

[dbminter]

With creating a bootable ISO from a set of files and a bootable image extract: nothing.  What I do is with a bootable flash drive, I use a piece of paid software called Macrium Reflect to image the flash drive.  It doesn't create ISO's though, but a proprietary file format it can write to flash drives.

[mdj2000]

it doesn't suit me. My goal is to create an obviously bootable ISO file. Thank you all the same. Do you think I should wait if some other expert on the forum and the ImgBurn program could help me or should I already close the thread with your previous answer, so it's not possible?

[dbminter]

Well, very few people actually patrol the forums much anymore.  So, you're probably not likely to get another answer.

 

In the meantime, if you haven't tried this already, see this Guide:

 

 

Unfortunately, this guide is fairly old and it was what I followed to try and create bootable ISO's that never booted.

[mdj2000]

Yes, I've seen that guide before. Unfortunately it is specific to a Microsoft file system. I haven't tried it. In fact my problem is also finding the famous boot image. I can't identify it as it's different from the guide. I think the structure created in the pen drive has to do with a Linux type operating system. Anyway, thanks for the support

[dbminter]

Yeah, sorry I couldn't help.  As I said, I've never successfully gotten a bootable ISO made by Build mode.

[mdj2000]

😔

[LIGHTNING UK!]

What’s the reason behind trying to create an iso from your usb stick rather than using the iso you originally downloaded?

The original iso was meant for burning to disc. What Rufus has created on your usb stick isn’t.

[dbminter]

If you have a bootable ISO you downloaded and wrote to a USB flash drive, why do you want to create a new bootable ISO?  Did you add files to the flash drive and want them rolled up into a new bootable ISO?  If so, for that, I use a piece of paid software called UltraISO.  It allows you to inject files into an existing ISO.

[mdj2000]

the basis of this thread is creating an ISO file from a bootable USB pen drive. I started from the Kaspersky Rescu Disk base because I had the test ISO and it is available for anyone who wants to answer me and find a solution. It is obvious that if I have an ISO that without it I have to create a bootable USB pen drive and then create the ISO again. I actually have a bootable USB stick with the OnTrack EasyRecovery program bootable. The program itself creates this bootable USB pen drive. There is no ISO that I could handle differently. So here's the dilemma.
So like in the first post, I have a bootable USB pen drive and I want to get a bootable ISO file.

There are also other programs that allow you to create bootable pen drives but do not create ISOs.

Now if it exists (and I think so, perhaps we need to look in the boot image for the solution) let's try to find the solution.

Thank you all

[dbminter]

I remember doing a search online towards the end of last year for something to make ISO's from bootable flash drives.  I had this application that would create a bootable flash drive and then you could select ISO's from the flash drive for booting from.  That way, you don't need multiple flash drives, just multiple ISO's on one flash drive.  I found nothing that could make ISO's, like you said.  And as I said, Macrium Reflect does not create ISO's.  It instead uses a proprietary format.

 

Is there a particular reason why you need ISO specifically and that any of those other program's read file formats aren't suitable?

[mdj2000]

Probably the program you are referring to is ventoy (open source). A utility that formats the USB pen drive and makes it multi-bootable. The program partitions the drive into two parts, the first with a very small operating system, the second available for the user to copy multiple bootable ISOs inside.

Unfortunately OnTrack EasyRecovery does not create CDs or ISOs but only bootable USB pen drives. Extracting the files for a bootable ISO from the pen drive would be much more malleable and flexible as a solution, because an ISO can be managed much more easily without tying up a pen drive for a long time.

[dbminter]

It was, indeed, VenToy I was referring to.

[mdj2000]

Bingo. I did it. As I said before it was all a question of information. I'm transcribing them so they can be useful to someone else.
The boot image is X:\boot\grub\i386-pc\eltorito.img in the case of the Kaspersky image.
Platform image: 80*86
Load segment: 07c0
Sector to load: 4
Patch boot Information Table.

But the most important thing is to manage the restrictions. That is ISO9660 and clicking on the year 1999 thus enables name length and other various variables which I will not explain in detail here.

Created the ISO from the pen drive and... voilà success. However, I thank everyone for their help and collaboration. I'll try OnTrack EasyRecovery tomorrow and let you know. Greetings

[mdj2000]

Even with OnTrack solution found. Thank you all for the support