You need to make the file executable with e.g.
chmod +x VBoxLinuxAdditions.run
and then run it. If you check with
ls -l again afterwards, you will see that the
x flag will be set, for "executable".
Quick summary from Wikipedia:
There are three specific permissions on Unix-like systems that apply to each class:
The read permission, which grants the ability to read a file. When set for a directory, this permission grants the ability to read the names of files in the directory (but not to find out any further information about them such as contents, file type, size, ownership, permissions, etc.)
The write permission, which grants the ability to modify a file. When set for a directory, this permission grants the ability to modify entries in the directory. This includes creating files, deleting files, and renaming files.
The execute permission, which grants the ability to execute a file. This permission must be set for executable binaries (for example, a compiled C++ program) or shell scripts (for example, a Perl program) in order to allow the operating system to run them. When set for a directory, this permission grants the ability to access file contents and metainfo if its name is known, but not list files inside the directory (unless read is set).
Edit: as noted in the comment below (or in the original post if one notices the path
/media/cdrom0/) the file was on a read-only media. Either the complete structure could be copied to a writable medium and the permissions changed, or one could run them directly from the disc with an explicit interpreter such as
If none of these interpreters work, one can check the intended interpreter with e.g.
head -1 VBoxLinuxAdditions.run
but it is most likely a regular shell script.