- There are two computers running GNU/Linux, U and T.
- U is untrusted and T is trusted.
- A non-executable file F (which may however have been infected with malware) resides on U. (For instance, an H.264 video file in a .mov wrapper.)
- It is needed to copy that file to T and to view that file on T, with minimal risk of compromising T.
- The human operator has both root and physical access to U and T.
- U and T can optionally be connected by LAN.
- U and T both have USB sockets and SD-card slots. A USB stick and an SD card, each large enough to contain F, is available.
- No proprietary software can be used.
There are various possible methods for copying the file from U to T and viewing it on T. Here are two examples:
- Update ClamAV on T. Use firewall on T to disallow all incoming connections. Connect U and T via LAN. Initiate an SCP command from T to U to retrieve a copy of F. Scan F with ClamAV on T and modify F if necessary (e.g. disinfect). View F on T with most well-audited software available (e.g. in case of video files I guess this might be mplayer or VLC or suchlike).
- Update ClamAV on T. Copy F from U to USB stick or SD-card and from there to T. Scan F with ClamAV on T and modify F if necessary (e.g. disinfect). View F on T with most well-audited software available.
You may be able to think of other methods.
Of the various possible methods for copying the file from U to T and viewing it on T, which has the lowest risk of compromising T, and why?