Malware issue

Hi
Wordfence reported the following as malware:

Filename: wp-content/class-wp-config-sys.php
File Type: Not a core, theme, or plugin file from wordpress.org.
Details: This file appears to be installed or modified by a hacker to perform malicious activity. If you know about this file you can choose to ignore it to exclude it from future scans. The matched text in this file is: $_COOKIE;(count($

The issue type is: Backdoor:PHP/cookie.count.10422
Description: Code often seen in file managers and backdoors.

Any advice would be appreciated. Several other files were tagged with similar coding.

Thanks

RTAFFY