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Preamble: Recently I came across an interesting story about people who seem to be sending emails with documents that contain child pornography. This is an example (this one is jpeg but im hearing about it being done with PDFs, which generally cant be previewed) https://www.youtube.com/watch?v=zislzpkpvZc This can pose a real threat to people in investigative journalism, because even if you delete the file after its been opened in Temp the file may still be recovered by forensics software. Even just having opened the file already puts you in the realm of committing a felony.

This also can pose a real problem to security consultants for a group. Lets say person A emails criminal files, person B is suspicious of email and forwards it to security manager for their program. In order to analyze the file the consultant may have to download it on a harddrive, even if they load it in a VM or Sandbox. Even if they figure out what it is they are still in this legal landmine area that bad timing could land them in jail for 20 years. Thinking about this if the memory was to only enter the RAM then upon a power down all traces of this opened file would disappear.

Question: I have an OK understanding about how computer architecture works, but this problem presented earlier made me start wondering. Is there a limitation, at the OS, hardware, or firmware level, that prevents a program from opening a stream of downloading information directly to the RAM? If not let's say you try to open a pdf, is it possible for the file it's opening to instead be passed to the program as a stream of downloading bytes that could then rewrite/otherwise make retention of the final file on the hdd impossible?

Skyler
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Unfortunately I can only give a Linux/Unix based answer to this, but hopefully it is helpful and extends to Windows too.

There are many ways to pass data between programs without writing to the hard disk, it is usually more of a question of whether the software applications support it (web browser and pdf reader for your example). Streams can be passed via pipes and sockets, but the problem here is that it may be more convenient for the receiving program to seek back in the stream at certain points rather than store all the data in memory. This may be a more efficient use of resources too. Hence many programs do not do this. Indeed a pipe can be made to look like a file, but if the application tries to seek backward, it will cause an error.

If there was more demand for streaming data to applications, it would probably be seen in more cases though as there are no major barriers. Currently it is more common just to store pdfs in a temporary file if they are viewed in a plugin and not downloaded. Video can be different though.

An alternative is to use a RAM drive, it is common for a Linux system to have at least one set up by default (tmpfs), although it seems for Windows that you have to install additional software. Using one of these removes the above limitations and it is fairly easy to set a web browser to use it for temporary files.

Graeme
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