How to decrypt this kind of code?

Question

Programming

Guys. There is, for example, such an obussified and encrypted code. That's where it started. Somehow I saw a good article on Habré, with step-by-step actions for decryption (now I can’t find it). Please direct what to google so that this abracadabra turns into magic?

$OOO000000=urldecode('%66%67%36%73%62%65%68%70%72%61%34%63%6f%5f%74%6e%64');$OOO0000O0=$OOO000000{4}.$OOO000000{9}.$OOO000000{3}.$OOO000000{5};$OOO0000O0.=$OOO000000{2}.$OOO000000{10}.$OOO000000{13}.$OOO000000{16};$OOO0000O0.=$OOO0000O0{3}.$OOO000000{11}.$OOO000000{12}.$OOO0000O0{7}.$OOO000000{5};$OOO000O00=$OOO000000{0}.$OOO000000{12}.$OOO000000{7}.$OOO000000{5}.$OOO000000{15};$O0O000O00=$OOO000000{0}.$OOO000000{1}.$OOO000000{5}.$OOO000000{14};$O0O000O0O=$O0O000O00.$OOO000000{11};$O0O000O00=$O0O000O00.$OOO000000{3};$O0O00OO00=$OOO000000{0}.$OOO000000{8}.$OOO000000{5}.$OOO000000{9}.$OOO000000{16};$OOO00000O=$OOO000000{3}.$OOO000000{14}.$OOO000000{8}.$OOO000000{14}.$OOO000000{8};$OOO0O0O00=__FILE__;$OO00O0000=0xaa70;eval($OOO0000O0('JE8wMDBPME8wMD0kT09PMDAwTzAwKCRPT08wTzBPMDAsJ3JiJyk7JE8wTzAwT08wMCgkTzAwME8wTzAwLDB4NGEzKTskT08wME8wME8wPSRPT08wMDAwTzAoJE9PTzAwMDAwTygkTzBPMDBPTzAwKCRPMDAwTzBPMDAsMHgxN2MpLCdzdzNEa2V4bFI1cllpTmMrem85Q0FVdnU0UUgvT0lYRThGV2YwYTZUN3FMS0d5MmptVnBCTWhidEpkbjFTWmdQPScsJ0FCQ0RFRkdISUpLTE1OT1BRUlNUVVZXWFlaYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU2Nzg5Ky8nKSk7ZXZhbCgkT08wME8wME8wKTs='));return;?>M\FwG^sRMHC{K5kZ+iDw+iDw+iDhBIl5EO6Um/xefQ98TuhZx9AVeuhSTY3RTRWJ0CMZ+ikSmCBsmYWRTRWm0CMZ+iDsmikSmr3o+CMSmiDsmikS75kSmCBsmCMSmi380CBsmikSmCBsmY3o+CBsmCBsmiDsqY3IBIBNkHbUJ/eRhOaaqC6iKX6SdzMeUITAMAA8jCMa4oCFxUb4m4CQANtei9MIdi6qyUTw3CvFWIkq0/feCv6Iz+9OG5Me3zMoeo0IR9AqYCkhcChwoAaNAUUQuveaH4v5fQxU6QbFqH6yG/vdjOlepOtohITIJXu7miCRBNDAbNB8drpSTr90qcbQf/xZBQ980CBsmikSmCBsmrCyaI6eGr3o+CBsmCBsmCBsqcm==36IG/b5F/3s85xFjOtzG5xVq4hZKQu0G5lwaO6hqOtNq/bdE/vUBObeTQCGr5xVq4bU2ObUEQ6aGQUZ24vhaRDM85eZCoU5voU5/5Mo+zhUNoAdAuh5+ChzTu9JTYbVq4bU2ObUEObmj/xafQvdBQ9dMXlzTcm70/xafQvdBQUZ6/bV0Qu5E/6eyQ9sZR3oEAMU9U0U9vpIkCMNUCAUcUeZ9CMZA5hM25pZGHvNa/

Answer 1

Look here and here .

Answer 2

replace "eval" with "var_dump" and lo and behold!

Answer 3

malzilla to help, but not everything takes. Do you really need it if you don't understand how this code works?

Answer 4

or use the online service here