Creating invalid filenames

Help on how to use HxD.
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Creating invalid filenames

Post by chilltuner »

Hello there, I was wondering on how to create a file that has "illegal" filenames with HxD.

From googling I noticed that the only really illegal character (unix) is the / for cataloges.
Say I wanted to have a filename with "'(document.domain); How would one go around doing this?
Best regards // chilltuner

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Re: Creating invalid filenames

Post by Maël »

Besides doing that for research purposes, I wouldn't recommend doing it. Invalid filenames may cause problems, because they contain unexpected characters, so data may be handled incorrectly and you could incur data loss.
Hiding data this way is not really reliable either, it's better to use encryption.

That being said, the approach is to circumvent the normal tools that protect against invalid filenames, and go to lower levels, where such checks are not performed.
This means you have to use the disk editor, to edit the logical disk which contains the filename you want to change. You will have to locate the place where the filename is stored on the disk, which depends on the file system that is used. Common ones are FAT, NTFS, ext3. Look up their structure to locate the filename.

If you just create a small image file, say for a virtual floppy disk, you could also just search the disk/image for the filename, if it is reasonably unique and not part of any other data on the disk/image file. Then just overwrite the filename with whatever characters you want. But make sure to not use more or less characters than the original filename.

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