Recommended way of writing to a Hidden/ReadOnly File C# - c#

I am trying to write to a file which has the following attributes - Hidden and ReadOnly. My process should be able to write to it but other processes have ReadOnly Access.
The procedure that I am following is:
Check if file exists
Remove the existing attributes on the file, i.e. hidden and readonly
Finish writing to the file
Apply the attributes (hidden and readonly) back to the file
I know that this is not the recommended way to use the File Attributes and write to a hidden file. Is there a nicer way to accomplish my task?
Thanks in advance.

Yes, make your application impersonate a special account. Give file write permissions to that account on that file and read access to all other accounts.
The simplest way to run in the context of another user is to press shift and right click the exe-file, pick "Run as different user".
With a windows service you change the running account from the service properties. The same goes with Windows Scheduled tasks.
To change the running account "in the middle of the process" you need to do some more work, find a good article on the subject, like http://www.codeproject.com/Articles/4051/Windows-Impersonation-using-C .

As #Albin notes, the correct way to address the access issue is with file permissions, not attributes.
If the file is hidden because you don't want users to be able to view its contents, I'd suggest a simple (relatively lightweight) encryption mechanism would be a better solution than the hidden attribute.
Note, both the hidden and read-only attributes can be turned off by a user with sufficient privilege. And typically anyone can turn on the "show hidden files and folders" feature in Explorer.

There's no need to remove the hidden attribute. I know of no other solution with the readonly one, though.

Related

Hide or Protect .txt save data c#

I have a program where a User can put data in a listBox, and this listBox can be saved by button click encrypted to an .txt file.
With any program start, the program loads and decode the Save-data back to the listBox.
So if anyone opens the save.txt, nobody can read it because its encrypted, but the users are still able to manipulate the encrypted textfile, so its not possible to load it back in my listBox.
Is the a way that my Form App, saves this .txt in a password protected folder or make something like invisible .txt files, only the Program can see?
You may make your file, Hidden, or even give it a System attribute that can be a precaution, but still, it is not very safe.
You can use SqlServer database to save your list, that handles encryption for you. (of course, if the user has admin privileges) he can still open and manipulate its data.
You may use Properties.Settings (AppSettings) too, but as I already said each option can have its advantages but not 100% safe, for a user with privilege.
First thing you need to work out is if you are over thinking this, is not hiding it and encrypting enough, why are people going to track down your file and mess with it?
However you do have a plethora of options, though you can hide it as much as you like yet the only way to stop dirty little fingers touching your data is put behind a remote web server.
However failing that,
You can stuff it in a database with restricted permissions
Put it in App Settings where its less obvious to find
and/or Create an account and impersonate that user in your application and programmatically restrict permissions to your file
Hide it in the registry (meh)
You could do something weird like append it to the end of a dll
Even change the extension to your file, and sociologically impersonate another file type like an exe or dll, make it less obvious
Though really if you want to restrict it, just create a web sever, give the user a login and password, and save it there, no dirty little fingers.

c#.net application which can opened while opening a folder

I would like to create a c# application which will open when i open a folder automatically.
My c# application is intended to be like a password system, so that the contents in the folder can only viewed after logging in to my application. Everything is ready..........
but i am confused how to open my application directly while opening the folder with a c# script?
I have now created a application which will ask the user for name and password while opening the application and now i want to make it open through the folder to be locked , how to do it?
Ok, first of all if you want the folder to be secure you should encrypt it otherwise all the user has to do to gain access is kill the process.
What i would recommend you do instead is create a encrypted file. For example a zip file. Then all you have to do associate the file with the program and to unpack it with the password. Then when the user is done delete it and overwrite the temporary folder. It's really important that you overwrite it otherwise the encryption is useless.
If you want to avoid conflict with other programs that work with zip files you can make your own file type it does not affect the content of the file in any way.
I hope this helps.
To make sure I understand... you want to build an application that will, when someone tries to open it, will only open after they supply a password. Hmmm... okay. A specific folder, or any folder? Local folders or folders on network shares? I initially was thinking a file system watcher approach, but that will only work on change events, like copying, renaming, deleting, etc. So that won't work. The closest would be to check last accessed time, but that is an alert ex post facto, so this must be rejected. I'm not sure how you could do this in C#. What is wrong with the robust security options MS has already established, like global groups. That provides flexible restrictions on access. Especially over large amounts of folders. Are users going to have one password per folder? Too cumbersome. One password per user? Use Windows authentication to lock it down. How is this app storing the passwords?
I recommend trying to leverage existing technology to solve problems before trying to re-invent the wheel. You have omitted the scope of this, and what you have already attempted, so we may not understand completely.

Creating a custom password protect file program

I know this isn't a strait up code question, but I'm trying make a program that could possible be running in the background of my computer, and allow me to leave my files/folders where they are, and upon double clicking on a file/folder a dialog box comes up asking for a password. All these programs that are on the market require you to move files around, create new volumes; I don't want that, I want simplicity. One dialog box with password promt, then file/folder opens. My question is what do I need to look into coding wise to make this possible? Thanks for any advice/tips. :)
FileSecurity()
Also Is this something that can only be done with NTFS and not FAT?
You can not detect when someone click or double click a folder, so no, it is not possible.
you can use FileSystemWatcher to detect when a file is opened and handle the open event, but unfortunately you cannot prevent its execution
I can think of only three ways how to SECURELY protect file:
write filesystem driver (similar used by antivirus software for example), but isn't not possible in C#
encrypt all files when user locks folder and decrypt them back when user unlocks folder.
for non-admin accounts, you can set privileges (and on NTFS also built-in file encryption) in such a way, that without admin password user can't access them
Method used in article you mentioned is not secure at all (any user can just rename the folder back to get access to protected files). Though you can use the same trick to run you program automatically when user double-clicks protected folder and unlock files if user enter correct password.

C# Detecting server setup

I'm writing a program that deals with the logs generated by the clients server. How can I detect where the user is storing them? It feels invasive to search all files, but what if they're being stored outside of the root. Is this acceptable, what if I make the user click "detect" first? Regardless, what if they've been renamed and reformatted? Is it possible to read the server settings themselves from my external program? I want this to work on linux and windows servers. I need WC3 Extended format w/ several fields enabled that are not naturally. I also don't want it to return null if it's enabled but no log has been yet created. I don't want to force the user (assumed dumb) to play with settings.
Any ideas?
Hardcode where you expect them to be in the common case, and if they're not there, ask the user about it. Doing more "magic" than that seems like a recipe for over-complexity and mistakes.
If the user is specifying the location of the log file, then either you should have the user locate the file(s) themselves or keep track of these locations somewhere else when they are saved. You don't need to be doing a full (or large partial) drive search.

How do I programmatically check EFFECTIVE delete (modify) or write permissions in .NET?

Sorry in advance for the long question.
What I'm really interested in is a way to programmatically check if the executing windows identity has adequate windows privileges to write to a directory (or file) in an ASP.NET web services application. But I'll settle for retrieving effective delete (modify) privileges for a user for a given directory or file. The problem is that I would like to be able to do this without either writing temporary files OR necessarily performing the IO action and handling the exception.
Yes, there is a question on this already ( see How can I programmatically determine if I have write privileges using C# in .Net?)
Normally I would agree with the accepted answer that the best method is to just try the IO action and handle any exceptions -- System.IO methods do throw System.UnauthorizedAccessException to indicate failure as a result of privilege denial. But in the case of of UPLOADING files, I'd really like to check the privileges BEFORE wasting the time and resources of uploading the data since it is only AFTER upload that we can attempt to write the file or folder in question. I pity any users uploading a 2GB file over http only to be told after the upload completes that they don't have permissions to upload the file to the destination.
The usual approach to testing write access if you don't want to perform the actual write is to write a temporary file. The other question has an answer pointing this out. This is what our code currently does. BUT windows security allows write access without delete privileges. Users with ONLY write access but no delete end up leaving all sorts of undeleted .tmp files. And no, we don't want to use a Domain admin account to reset the ACL on the tmp files and then delete them. The approach I've been taking is to check if the user has write privileges using System.IO.Directory.GetAccessControl(..) or System.IO.File.GetAccessControl(..) and dealing with the various access rules and ACE returns... but with this I still have issues dealing with EFFECTIVE privileges -- i.e. in most cases I also have to look up the user's membership in any of the groups listed in the ACE that do have permissions on the object. There has to be an easier way.... doesn't there?
Well kudos for going the extra mile on user experience AND trying to maintain clean program structure. Maybe if you're uploading only you could try to create an empty 'placeholder' file with the same name as the final 2GB file will have, then just overwrite it. Not perfect since you could still end up with an empty file, but pretty easy and at least a little bit more elegant that some of the alternatives.
You could also have permanent file, say 'access_test.txt', which you try to overwrite with a datestamp or something to first to test the current access.

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