**Description**
> Run it and get flag (but how?) (segfault is NOT a bug)> > attachment: https://drive.google.com/open?id=1ghFVktqDYM48YiJt-ppx6a-2JHH-wIKm
**Solution**
Apparently the simplest challenge of the CTF, the executable seems to contain the wine runtime and some emulated Windows functions, dialogs, Notepad stuff ...? Perhaps it runs properly on a Linux desktop with a graphical environment / X11?
For my actual solution however, I loaded the executable into radare and after analysing the functions with `aaa`, `afl` produced:
    0x7f7f96534000    8 192  -> 194  obj.imp.__wine_main_argv    0x7f7f96545cd0    1 6            sym.imp.__wine_dll_register    0x7f7f96545ce0    1 6            sym.imp.__stack_chk_fail    0x7f7f96545cf0   21 270  -> 256  entry0    0x7f7f96545e00    3 33           sub._ITM_deregisterTMCloneTable_e00    0x7f7f96545e70    4 50           entry2.fini    0x7f7f96545eb0    5 5    -> 56   entry1.init    0x7f7f96545ec8    1 6            fcn.7f7f96545ec8    ...    0x7f7f96546238    1 6            fcn.7f7f96546238    0x7f7f96546481    5 256          sym.ShowLastError    0x7f7f96546581    6 295          sym.UpdateWindowCaption    0x7f7f965466a8    8 359          sym.DIALOG_StringMsgBox    0x7f7f96546a32    3 129          sym.FileExists    0x7f7f96547074   14 208          sym.DoCloseFile    0x7f7f965471fa   47 1579         sym.DoOpenFile    0x7f7f96547825    3 121          sym.DIALOG_FileNew    ...    0x7f7f96549e44    1 65           sym.DIALOG_FilePageSetup    0x7f7f9654a192    1 124          sym.SetFileNameAndEncoding    0x7f7f9654a20e    9 195          sym.get_dpi    0x7f7f9654bb68   17 684          sym.NOTEPAD_DoFind    0x7f7f9654ce46   18 1356         sym.WinMain    0x7f7f9654fff8    1 8            reloc.__cxa_finalize
Of interest was really mainly `sym.WinMain`, so with `pdf @ sym.WinMain`, I found a line that said:
    ...    |      |    0x7f7f9654d263      488b4018       mov rax, qword [rax + 0x18] ; [0x18:8]=-1 ; 24    |      |    0x7f7f9654d267      488d159a0800.  lea rdx, str.RCTF_WelCOme_To_RCTF ; 0x7f7f9654db08 ; u"RCTF{WelCOme_To_RCTF}\n\n\u5700\u6168\u3f74\u5920\u756f\u6420\u6365\u6d6f\u6970\u656c\u2064\u656d\u3f3f"    |      |    0x7f7f9654d26e      4889c1         mov rcx, rax    ...
And there was the flag:
`RCTF{WelCOme_To_RCTF}`
In fact, the flag was available in plaintext in the binary, but e.g. `strings` could not find it - it was encoded as UTF-16, taking two bytes per character. This is typical for Windows binaries, which is probably why this challenge used this setup.