B374k.php [top] Jun 2026

Modern variants employ AES-256-CBC encryption and advanced obfuscation designed to evade even popular antivirus solutions.

b374k allows file uploads. Monitor your /tmp directory. If you see PHP scripts writing to /tmp/sess_* or executing system() functions where they shouldn't, investigate.

PHP web shells like b374k have remained a persistent threat for over two decades, and there is little indication that this will change. Several trends suggest the threat may actually intensify: b374k.php

Delete the b374k.php file immediately, along with any other suspicious files in the same directory.

A built-in shell that allows the execution of system commands directly from the browser. If you see PHP scripts writing to /tmp/sess_*

To understand b374k.php , one must understand the hierarchy of web shells. There are dozens of families: c99 (the granddaddy), r57 , WSO (Web Shell by oRb) , b374k , and more modern ones like p0wny-shell .

: Beyond basic PHP execution, the script can run code natively in Perl, Python, Ruby, Java, Node.js, and C, depending on the binaries available on the host server. A built-in shell that allows the execution of

Some variants even use AES-256-CBC encryption to further obfuscate their presence.