Thanks for enabling comments!
Various reasons this is garbage:
- Executing shellcode without bypassing DEP
- Saying to 'just jump to system()' without having an ASLR leak
- 7zip doesn't even open this, you get "Error: Is not archive"
- Includes 9 different header files and uses none of them except 7zip's types
- Igor Pavlov (the creator of 7zip) does not believe this vulnerability exists
- The 'shellcode' is complete garbage. I compiled the program and had it print the shellcode (since it modifies it), here's it in assembly:
push   rbp
mov    ebp,esp
sub    esp,0x8
mov    DWORD PTR [rsp],0x636c6163
add    ah,cl
int3
int3
.byte 0x89
.byte 0x83
rex.W
rex

Please proceed to ignore anything else this guy posts,
- a real exploit developer