Question Program(s) to wipe slack

Oct 12, 2019
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I am looking for a program (for both Win 7 and Win 10), to specifically wipe the 'slack' at the start and end of files while leaving the file intact. Such programs existed in the 1990s, but I cannot find any now (I would prefer Freeware!): does anyone know of any please?
Thanks
 

kanewolf

Titan
Moderator
I can see from a security perspective that this could have some advantages if you are selling a PC. Otherwise I can think of no benefit. That may be why you can't find software to do what you want. Too much risk of corrupted data for too little benefit.
 
How do you define "slack"? Is this the space occupied on the drive with (eg) 8k sector size when the file you're storing is less than multiple of 8k?

You can'r reclaim this space back - it's taken, and can't be used. If you want to (eg) zero out that space, that's completely different question, but I see no practical use of this either.
 
Oct 12, 2019
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I ask because if a file is sent to someone, the file may contain personal information from other files in the top and tail ends ("slack").
Admittedly it was in the early 1990s, but when a friend first told me about this risk, I looked at a few files (with Norton Utilities I believe), and to my horror, one file had all my credit card details in at the very end of the file (after it had "officially" finished), and another contained references to lifelong medical conditions I have.
Strangely, no one seems to be bothered by (or know about?) this risk nowadays.
There is of course a host of other information, e.g., personal addresses, medical ailments, etc., that can be relayed in this manner, without the sender ever knowing.

There is an informative article on
https://whatis.techtarget.com/definition/slack-space-file-slack-space (the 3rd para. confirms what I am saying)

Alabalcho says "If you want to (eg) zero out that space, that's completely different question, but I see no practical use of this either", but surely if it has important/personal data, that is a good enough reason?

So, can anyone suggest a (freeware) program that shows the slack ends of a file and can provide the means of blanking this out?
Thanks.
 

Ketchup79

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Aug 7, 2019
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I don't believe what you are asking for is what you want. That is, you are talking about two different things. Writing zeros to empty space (which previously contained data) is very doable and plenty of apps out there to do it - here is a list of the top 8 - https://www.raymond.cc/blog/make-your-recoverable-datas-unrecoverable/.

What you seem to be describing is emailing personal files over the Internet. This should NEVER be done. In today's world, any files with personal info should be sent via a verified SFTP site/connection (if Internet) or shared ONLY if on an Intranet.

Back in the 90's, internet security was a concept and there were a lot of good "ideas" out there. Today there a regulations in place, which work pretty well as long as you utilize them (and work with others who do the same).
 

USAFRet

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I ask because if a file is sent to someone, the file may contain personal information from other files in the top and tail ends ("slack").
Admittedly it was in the early 1990s, but when a friend first told me about this risk, I looked at a few files (with Norton Utilities I believe), and to my horror, one file had all my credit card details in at the very end of the file (after it had "officially" finished), and another contained references to lifelong medical conditions I have.
Strangely, no one seems to be bothered by (or know about?) this risk nowadays.
AFAIK, that concept no longer exists. Has not in years.

I'm obviously open to anyone showing me otherwise, with actual results.
 
Oct 12, 2019
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"What you seem to be describing is emailing personal files over the Internet. This should NEVER be done. "

I am not talking about emailing personal files. I am talking about emailing a totally ordinary non-personal files (e.g., a photo of a mountain, or a doc/docx file with no personal information) but these 'pick up' or include data from another file on the hard disc, a personal one, which get lodged in at the slack ends of the non-personal file being sent.
I honestly don't think I can make it any clearer than this.
However, am I just caught up in a 1990s time warp and this problem in fact longer occurs?
If it does prevail, I return to my original question, i.e, are there any (freeware) programs that allow you to view the slack ends of a file that also allow you to zero out/delete anything in these ends that shouldn't be there?
I hope I have now made my question clear.
 

kanewolf

Titan
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I ask because if a file is sent to someone, the file may contain personal information from other files in the top and tail ends ("slack").
This would only be the case if the file is sent by sending the disk. The software reading the file stops at the end of file when attaching to an e-mail or copying to a USB. So being able to see personal information that was not overwritten on your hard drive is no more of a security risk than any other "available" section of that disk.
 

Ketchup79

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Hmm. A current docx file is not going to have info about your medical records unless you put them in the file. It WILL have whatever user name you denoted to Word as the author, but that's about it. Like I said above, computer "security" is actually an issue now, so the only way you would get medical data (in this example) off your computer is:
  1. Knowingly doing so
  2. Some type of Malware
 
Oct 12, 2019
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Thanks for these replies. It would therefore seem that security has improved (in nearly 30 years!).
As I say, in the early 1990s someone (very computer knowledgable) told me that files sent by emailing (text files, doc files, jpg images, etc) could include data from other files on the same disc.
I found this hard to believe, but sure enough on looking at the hex format of files, of different types, which were selected at random, there was indeed data from other files in the slack area. In one case, personal data.. This also applied to files emailed to me.
So (albeit speaking as a rank amateur), it would thus seem that the file creation method used by Windows is now much more secure!
Many thanks for the input. Much appreciated.
Regards
David
 

Ketchup79

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Just don't forget there were a lot of "snake oil" programs back then too. Tools that said your registry needed to be checked daily, your files needed to be cleaned, etc. I don't know about your specific instance, but an app could have just as easily scanned your entire hard drive to find your personal files, said it was attached to a picture, and performed some type of "work" to correct it. I certainly could have missed out on this, but I have been into computers since Windows 3.1 and never heard of a legitimate program that did such a thing (and that is including the helpful tools available at the time in Norton Utilities).

If you haven't looked at the history of Norton Utilities to see if the app you are thinking of is listed, a full version list is here:
https://en.wikipedia.org/wiki/Norton_Utilities#Version_1.0
 
Oct 12, 2019
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Ketchup79.
In fact, thinking back, I am now fairly sure that in those halcyon days, I wasn't using Windows, but DOS. Although Win 3 first appeared in 1990, I don't think many people used it until a few years later (and modem communication (requiring Hayes commands!) was with BBS (Bulletin Board Systems) and programs such as Telix (and then in the early days of the internet we had to edit our own win.ini files in order to connect to the ISP) Happy days!)
I can't recall the name of the Norton program used, but it allowed the viewing and editing of a file.

In sum, the move from DOS to Windows may explain why the anomaly of file contents appearing in the slack of other files' no longer occurs, i.e, this was a fault with DOS?
Regards
David
 

hang-the-9

Titan
Moderator
Thanks for these replies. It would therefore seem that security has improved (in nearly 30 years!).
As I say, in the early 1990s someone (very computer knowledgable) told me that files sent by emailing (text files, doc files, jpg images, etc) could include data from other files on the same disc.
I found this hard to believe, but sure enough on looking at the hex format of files, of different types, which were selected at random, there was indeed data from other files in the slack area. In one case, personal data.. This also applied to files emailed to me.
So (albeit speaking as a rank amateur), it would thus seem that the file creation method used by Windows is now much more secure!
Many thanks for the input. Much appreciated.
Regards
David
I have never head of this happening, when you create a file, that file will only contain what is in that file. It's not like a candy where if you drop it, it will pick up stuff off the ground. Never heard of a "slack" area in files, you don't remember anything else about how that was called what you are trying to describe? Now if you transfer a bunch of files through the network, the network packets may contain portions of different files and those network packets do have headers and footers (not "slack"). So when you view the packet data that is not encrypted you may see some from this file, some from that file.

Actual files on the computer don't mix under normal circumstances. It would be like a bunch of cars driving on a road going to the same place and when they arrive, the colors are mixed up and the drivers are in different cars, it just won't happen, the files are isolated like the cars. Only time this may happen if there were disk issues or an issue with the file system and some files got mixed up as to where the location on the disk was for them, then you may have several file data in wrong locations, but that would pretty much create a non-readable file. That would be like an accident on the way to the place where the cars crash into each other.
 
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Ketchup79

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Well Windows 3.1 and 95 were just a "shell" over MS DOS. Windows as a full control OS didn't start until 98, so there definitely could have been some weird programs back then. I didn't start really using a computer until Windows 3.1, and wasn't even in Windows much at that time. Unfortunately, my memory of those days is mainly of WordPerfect and the games I played (one having to boot off the floppy due to memory access issues) so I probably won't be able to help you much recalling that program.
 
Oct 12, 2019
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I have never head of this happening,

Well, I can assure you it DID happen! (I am not sure how a comparison with cars driving along is a suitable analogy) And it not only occured with me but others (the guy who told me about this became a highly esteemed (and highly-paid!) computer systems analyst.)
On reading replies here, I can only assume it was an anomaly in DOS (during the early 1990s and perhaps earlier) that no longer arises with Windows.
 

hang-the-9

Titan
Moderator
I have never head of this happening,

Well, I can assure you it DID happen! (I am not sure how a comparison with cars driving along is a suitable analogy) And it not only occured with me but others (the guy who told me about this became a highly esteemed (and highly-paid!) computer systems analyst.)
On reading replies here, I can only assume it was an anomaly in DOS (during the early 1990s and perhaps earlier) that no longer arises with Windows.
I have worked with hex editors in DOS days, there is no way for a file to just have info from another file stuck to it when you look at it unless there is an issue with the file system index where the file locations on the disk are not correct. Computer data is not like putty or water where it mixes in with stuff near it. That is why I used cars, they don't mix unless there is a crash. Data for files is separated, just like those cars. When you go to access the file or send it to another location, that data is still in the same car, it's just sent off a ramp, when it reaches the end of the ramp, it's still that same car.

I am guessing you are not clearly remembering what was explained or shown, especially since you were talking about "slack" with files which is not a term used with file systems.

If you look at data packets, yes there are fragments of different files that may be sent, and with bad security it may be possible to view several files in one packet. But if I open FILE_A.TXT on a computer, if it's a normally setup system, there is 0 chance that I can see what FILE_B has in it no matter what I use to look at it. When the file system has issues, then it may think that some part of one file is located in a part of the disk that it's not on, that usually leads to corrupt files.
 
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