SatyrScanPHP is a PHP based spam, hack, and virus scanner.
It is the child of BASH SatyrScan project. Which can be found on GitHub https://github.com/alleck/SatyrScan/tree/master/Current-Version
The steps are simple.
1: Download the zip file. https://github.com/alleck/SatyrScanPHP/archive/master.zip
2: Unzip the file.
3: Make sure that the scan.php and the Virusdb.txt are located in the site's root.
4: Visit http://URL/scan.php in a browser, and it will tell you what files are compromised.