How to regex match and regex replace string in php

Question

i have a piece of obfuscated code that i want to turn back to normal.

I came up with an idea of simple preg_replace_callback() and a preg_match() nested within it for the replacement.

For some reason though my code does not want to match, specially the preg_match in the callback

Here is a snippet of my code.

In my debbuging the arrays of preg_match_all() (I've tried regular preg_match() as well) return empty although it works outside of the callback.

<?php
$code = '
public function encrypt($UDw2y33pQ_22) { 
        goto eKGyEfM327pq; 
    YlzBCxTNCJzo: 
        $p7nCDJiybOtp = mcrypt_create_iv($I9ryzFUJtil4, 
    MCRYPT_RAND); 
        goto zqGNmmifhK7G; 
    eKGyEfM327pq: 
        $IE19PrOpdkbJ = "*97@$S8&8&*as&*SA7sa*SA7alnIU&7#$%gf^IsPj8"; 
        goto uR63Cxb5ZtRs; 
    uR63Cxb5ZtRs: 
        $I9ryzFUJtil4 = mcrypt_get_iv_size(MCRYPT_BLOWFISH, 
    MCRYPT_MODE_ECB); 
        goto YlzBCxTNCJzo; 
    TdHsUlVktK5b: 
        return base64_encode($pcLABic8Iiv1); 
        goto XJlxnac4pgAr; 
    zqGNmmifhK7G: 
        $pcLABic8Iiv1 = mcrypt_encrypt(MCRYPT_BLOWFISH, $IE19PrOpdkbJ, utf8_encode($UDw2y33pQ_22), MCRYPT_MODE_ECB, $p7nCDJiybOtp); 
        goto TdHsUlVktK5b; 
    XJlxnac4pgAr: 
}';
$deobfuscated = preg_replace_callback("/goto ([a-zA-Z0-9_]+);/", function($match){
    preg_match_all("/({$match[1]}:)((\s|\S)*?)([a-zA-Z0-9]{12}:)/ms", $code, $a);
    return $a[0][2];
},$code);

echo $deobfuscated;

Actual result:

public function encrypt($UDw2y33pQ_22) { 

YlzBCxTNCJzo: 
    $p7nCDJiybOtp = mcrypt_create_iv($I9ryzFUJtil4, MCRYPT_RAND); 

eKGyEfM327pq: 
    $IE19PrOpdkbJ = "*97@$S8&8&*as&*SA7sa*SA7alnIU&7#$%gf^IsPj8"; 

uR63Cxb5ZtRs: 
    $I9ryzFUJtil4 = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_ECB); 

TdHsUlVktK5b: 
    return base64_encode($pcLABic8Iiv1); 

zqGNmmifhK7G: 
    $pcLABic8Iiv1 = mcrypt_encrypt(MCRYPT_BLOWFISH, $IE19PrOpdkbJ, utf8_encode($UDw2y33pQ_22), MCRYPT_MODE_ECB, $p7nCDJiybOtp); 

XJlxnac4pgAr: 
}

Expected result:

public function encrypt($UDw2y33pQ_22) { 
    $IE19PrOpdkbJ = "*97@$S8&8&*as&*SA7sa*SA7alnIU&7#$%gf^IsPj8"; 
    $I9ryzFUJtil4 = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_ECB); 
    $p7nCDJiybOtp = mcrypt_create_iv($I9ryzFUJtil4, MCRYPT_RAND); 
    $pcLABic8Iiv1 = mcrypt_encrypt(MCRYPT_BLOWFISH, $IE19PrOpdkbJ, utf8_encode($UDw2y33pQ_22), MCRYPT_MODE_ECB, $p7nCDJiybOtp); 
    return base64_encode($pcLABic8Iiv1);
}

Sorry, thank you for pointint this out. I edied the post to reflect those — Repastificationer
– Repastificationer, Commented Aug 14, 2017 at 13:15
You're trying to deobfuscate code? Is this your code? Seems weird that you're trying to deobfuscate an encrypt function. — GrumpyCrouton
– GrumpyCrouton, Commented Aug 14, 2017 at 13:20

Nils Rückmann · Accepted Answer · 2017-08-14 13:20:04Z

2

$code is undefined within the closure. You need to pass it via use statement. Example:

$deobfuscated = preg_replace_callback("/goto ([a-zA-Z0-9_]+);/", function($match) use ($code) {
    preg_match_all("/({$match[1]}:)((\s|\S)*?)([a-zA-Z0-9]{12}:)/ms", $code, $a);
    return $a[0][2];
},$code);

You should also check for existing keys before trying to return $a[0][2].

answered Aug 14, 2017 at 13:20

Nils Rückmann

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