Finding Base64 Encoded Exploits

Jeff · 09-09-2010, 06:39 AM

When a PHP application is hacked and serving content that you cannot seem to find, chances are it is encoded in base64 and somewhere being decoded and displayed. Hackers will obfuscate this code making it hard to find. One way to find this code is to disable the base64_decode function in your php.ini file:

Code:

disable_function = "base64_decode"

Restart Apache and watch your error log to see where error messages pop up and this may allow you to see where the code is executing. Knowing where it executes is a great leap into finding HOW it is executing.

If none of your applications use base64_decode, then feel free to leave it disabled in php.ini. It will save you a lot of headaches in the future anyway.

12-09-2010, 05:58 AM

With “hacking” being a household word for anyone using computers, this is a fantastic method to find the encoded base64 which the hackers would have hidden somewhere when they did the mischief and if none of your applications use the base_64 decode the be smart and leave it disabled in php.ini as it'll save you a lot of trouble later!!

09-09-2010, 06:39 AM	#1
Jeff Administrator Join Date: Jul 2010 Posts: 402 Rep Power: 10	Finding Base64 Encoded Exploits When a PHP application is hacked and serving content that you cannot seem to find, chances are it is encoded in base64 and somewhere being decoded and displayed. Hackers will obfuscate this code making it hard to find. One way to find this code is to disable the base64_decode function in your php.ini file: Code: disable_function = "base64_decode" Restart Apache and watch your error log to see where error messages pop up and this may allow you to see where the code is executing. Knowing where it executes is a great leap into finding HOW it is executing. If none of your applications use base64_decode, then feel free to leave it disabled in php.ini. It will save you a lot of headaches in the future anyway.
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12-09-2010, 05:58 AM	#2
kajara23 Guest Posts: n/a	With “hacking” being a household word for anyone using computers, this is a fantastic method to find the encoded base64 which the hackers would have hidden somewhere when they did the mischief and if none of your applications use the base_64 decode the be smart and leave it disabled in php.ini as it'll save you a lot of trouble later!!
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