Question : mess with programs running as your user (without root) using only /proc

Is it possible to fiddle with things in /proc so say i have a linux elf c program running and all it does is sit in a loop sleeping for 10 seconds. can i meddle with something in /proc so it suddenly calls execve and turns into bash or even just make it call say getuid then printf the result (which is proabably harder than execve).

no using gdb or external tools, tho objdump and readelf and parsers are all ok but if its possible you must be able to do it only by modifying file objects in /proc.

Answer : mess with programs running as your user (without root) using only /proc

The answer is not hard, and I already answered it.  If it were possible, it would be considered a bug and fixed.