exfil xefil efxil fexil xfeil fxeil exifl xeifl eixfl iexfl xiefl ixefl efixl feixl eifxl iefxl fiexl ifexl xfiel fxiel xifel ixfel fixel ifxel exfli xefli efxli fexli xfeli fxeli exlfi xelfi elxfi lexfi xlefi lxefi eflxi felxi elfxi lefxi flexi lfexi xflei fxlei xlfei lxfei flxei lfxei exilf xeilf eixlf iexlf xielf ixelf exlif xelif elxif lexif xleif lxeif eilxf ielxf elixf leixf ilexf liexf xilef ixlef xlief lxief ilxef lixef efilx feilx eiflx ieflx fielx ifelx eflix felix elfix lefix fleix lfeix eilfx ielfx elifx leifx ilefx liefx filex iflex fliex lfiex ilfex lifex xfile fxile xifle ixfle fixle ifxle xflie fxlie xlfie lxfie flxie lfxie xilfe ixlfe xlife lxife ilxfe lixfe filxe iflxe flixe lfixe ilfxe lifxe
Note: these 'words' (valid or invalid) are all the permutations of the word exfil. These words are obtained by scrambling the letters in exfil.