Slack Space Within Files


New Member
Until recently, I had not heard of slack space existing within files. However, I found this site, which says the following:

"In addition to this slack space at the end of all files, the interior slack spaces of the compound files created by applications such as Word® and Excel® can also hold sensitive data scavanged by the reallocation of "deleted" clusters to those files."

From what I gather, the FAT file system wouldn't initialize slack data in OLE files, but NTFS would.

The above example seems to indicate a (rare) case in which unallocated space could inadvertently end up in a file. I'm wondering if there are other situations in which this is possible. If so, I'm also wondering which file types are susceptible to this and which aren't. I had never heard of this scenario before, so I'm wondering how common it is!
Generally, most database-type files would also have the same problem as records are removed and reshuffled. Slack data within files would apply to any filesystem, not just FAT as since the data officially belongs to the file, the filesystem isn't aware about it.
Thanks for your reply!

So, database-type files are susceptible to this "internal slack". Normal files like MP3, TXT, PDF, JPEG, etc. don't have this problem, right?
Well, normal differs for people, but yes MP3, TXT, PDF, JPEG shouldn't have it.

Having said that, the Old New Thing blog post you mentioned referred to a separate kind of issue than what the first article was referring to, so I don't know what you're actually getting at.
You're right, I think I misread the Old New Thing article. My question was regarding the first article, and that's been answered. Thanks!
i am curious to know the answer of this question too please

garrett01 said:
Eraser will wipe the cluster tips of the files during freespace erase.

My run give me a long list of warnings that cluster tips were not erased because it is either a system file, or because I did not have required permission. How can I fix this?