Once I have a meterpreter shell on the machine, I opened a MS-DOS prompt with this command:
execute -f cmd.exe -i -H
Then, I would like to edit a file with edit file_name, but I don't know how to save the file (normally you have to use the MS-DOS menu but there is no such thing in a meterpreter session).
Do you have any idea how I can achieve my goal?
It might be easier to not edit the file on the target box but on the attacking box, you can easily do this by the two meterpreter commands upload / download and a local editor of your choice.
Check out meterpreter's edit command:
The ‘edit‘ command opens a file located on the target host. It uses the ‘vim’ so all the editor’s commands are available.
Please refer to the “vim” editor documentation for more advance [dic]use. http://www.vim.org/
This should be issued in the meterpreter shell, not the command shell (i.e. before you run execute).
Depending on how much editing you need to do, you can use echo with output redirection (> to overwrite a file with your output, >> to append to a file) to edit a file. For example,
echo This line will replace the contents of this file > file1.txt
echo This line will be appended to the file's end >> file2.txt
If you need to do more fine-grained editing than that and you're on a modern Windows version, you can use powershell, which gives you a much more powerful scripting engine (although you will still need to script out the editing). If you were actually on DOS (you aren't!), or are on a 32-bit Windows version, you could use edlin. You do not want to use edlin.
Of course, since what you're actually trying to do is "edit a file via meterpreter", which has nothing to do with cmd.exe much less MS-DOS, you should just use meterpreter's edit command, as the other answers say.
