neopi(1) web shell code detection


neopi [options] <dir> [regex]


This manual page documents briefly the neopi command.

neopi is a Python script that uses a variety of statistical methods to detect obfuscated and encrypted content within text/script files.

The intended purpose of NeoPI is to aid in the detection of hidden web shell code.

The development focus of NeoPI was creating a tool that could be used in conjunction with other established detection methods such as Linux Malware Detect or traditional signature/keyword based searches.

NeoPI recursively scans through the file system from a base directory and will rank files based on the results of a number of tests.

It also presents a “general” score derived from file rankings within the individual tests.


The program follows the usual GNU command line syntax, with long options starting with two dashes (`-'). A summary of options is included below.

-v, --version
Show version of program.

-h, --help
Show summary of options.

Generates a CSV output to FILECSV containing the results of the scan.

-a, --all
Run all tests including entropy, longest word, and index of coincidence. This is the recommended way of running neopi.

-e, --entropy
Run only the entropy test.

-l, --longestword
Run only the longestword test.

-c, --ic
Run only the Index Coincidence test.

-A, --auto
This flag runs an auto generated regular expression that contains many common web application file extensions.

This list is by no means comprehensive but does include a good ‘best effort’ scan if you are unsure of what web application languages your server is running.

Current list of included extensions: php, asp, aspx, sh, bash, zsh, csh, tsch, pl, py, txt, cgi, cfm


neopi -C scan1.csv -a -A /var/www/

neopi -a /tmp/phpbb "php|txt"

neopi -a -A /var/www/html/


neopi authors are Ben Hagen <[email protected]> and Scott Behrens <[email protected]>.

This man page was written by Arturo Borrero Gonzalez <[email protected]> for the Debian GNU/Linux distribution (but it may be used by others).