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Igor_Kavinski
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Virtualbox extension pack installation and file formats that are actually zip in disguise

Wed Jan 15, 2020 10:11 am

For some weird reason, after updating Virtualbox to the latest version 6.1.2, I was unable to install the corresponding extension pack. It would just hang while installing and there was no way to close it other than using End Process in Task Manager. So I thought, F that and proceeded to run my saved VM, except it wouldn't run due to USB 2.0 enabled in it and that required the extension pack. Now I was in a serious pickle (I hate losing my work especially when a saved VM session is lost). On a lark, I changed the extension of the extension pack to zip. Double-clicked it and it opened in Winrar! There was another file of the same name in it, just without any extension. I extracted that and gave it the zip extension and whaddayaknow? It opened again revealing a set of files. I opened Virtualbox's installation folder and went into the extension pack folder (C:\Program Files\Oracle\VirtualBox\ExtensionPacks). Checked the XML file in the Oracle_VM_VirtualBox_Extension_Pack folder and turned out that it was the currently installed extension pack for the previous version. Made a copy of this folder, deleted everything in the original folder and placed the files from the newer extension pack version into this folder. Double clicked my saved VM with a beating heart and SUCCESS! Everything is back to normal. Hope this helps anyone else having such trouble.

Which brings me to my question: How many other files have you all experienced to be actually zip files in disguise? I know xlsx and docx are zip files because I was curious why the same file's size was smaller in the x format so changed the extension to zip and turned out it had xml files in it. Relate your similar experiences, if any.
 
Waco
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Wed Jan 15, 2020 7:59 pm

There are many many file types that are tar/zip/rar files in disguise. It's a pretty common way of obfuscating the contents of a particular piece of data.

If you want to go on a trip - Google way to hide data in zip/rar/tar files. :)
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meerkt
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 10:06 am

Yeah, it's common. Java's JAR and Android's APK are other examples.

I wouldn't call it obfuscation. It's just a simple way to package a bunch of files. You can use existing ZIP libraries, there's a file index for quick seeking, and there's compression that's pretty fast (for an old format) to decompress.
 
Igor_Kavinski
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 11:03 am

meerkt wrote:
I wouldn't call it obfuscation. It's just a simple way to package a bunch of files.


True but I wish Windows would give an option in Explorer's advanced options to read file headers and indicate the file's format regardless of the extension.
 
just brew it!
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 11:33 am

Igor_Kavinski wrote:
meerkt wrote:
I wouldn't call it obfuscation. It's just a simple way to package a bunch of files.

True but I wish Windows would give an option in Explorer's advanced options to read file headers and indicate the file's format regardless of the extension.

Kind of unreasonable to expect Microsoft to know how to parse the headers of every 3rd party file format.
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meerkt
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 11:36 am

Shell extensions.

But hardly worth the trouble nowadays, since MS has turned the shell into an unstable platform that's always in flux.
 
just brew it!
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 11:44 am

Shell extensions come with their own set of problems. It ties the stability and security of Windows Explorer to the quality of 3rd party shell extension plugins.
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Igor_Kavinski
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 11:46 am

just brew it! wrote:
Kind of unreasonable to expect Microsoft to know how to parse the headers of every 3rd party file format.


Not every format. Just the ubiquitous ones.
 
Waco
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 6:15 pm

Igor_Kavinski wrote:
just brew it! wrote:
Kind of unreasonable to expect Microsoft to know how to parse the headers of every 3rd party file format.


Not every format. Just the ubiquitous ones.

Assuming they can perfect the interpreter so that it doesn't do insane things when a non-ubiquitous format happens to match that common one...
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Redocbew
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Re: Virtualbox extension pack installation and file formats that are actually zip in disguise

Thu Jan 16, 2020 6:23 pm

Not to mention Igor is probably using "zip files" interchangeably with any method of file compression in general. I imagine we've had the same few formats for general file compression for so long just because there's no pressure on improving it the same way there is with streaming video.
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