FastFinder - Incident Response - Fast suspicious file finder

What is this project designed for?

FastFinder is a lightweight tool made for threat hunting, live forensics and triage on both Windows and Linux Platforms. It is focused on endpoint enumeration and suspicious file finding based on various criterias:

• file path / name
• md5 / sha1 / sha256 checksum
• simple string content match
• complex content condition(s) based on YARA

Ready for battle!

• fastfinder has been tested in real cases in multiple CERT, CSIRT and SOC use cases
• examples directory now include real malwares / suspect behaviors or vulnerability scan examples

Installation

Compiled release of this software are available. If you want to compile from sources, it could be a little bit tricky because it strongly depends of go-yara and CGO compilation. Anyway, you'll find a detailed documentation for windows and for linux

Usage

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  2021-2022 | Jean-Pierre GARNIER | @codeyourweb
  https://github.com/codeyourweb/fastfinder  

usage: fastfinder [-h|--help] [-c|--configuration "<value>"] [-b|--build
                  "<value>"] [-o|--output "<value>"] [-n|--no-window]
                  [-u|--no-userinterface] [-v|--verbosity <integer>]
                  [-t|--triage]

                  Incident Response - Fast suspicious file finder

Arguments:

  -h  --help              Print help information
  -c  --configuration     Fastfind configuration file. Default:
  -b  --build             Output a standalone package with configuration and
                          rules in a single binary
  -o  --output            Save fastfinder logs in the specified file
  -n  --no-window         Hide fastfinder window
  -u  --no-userinterface  Hide advanced user interface
  -v  --verbosity         File log verbosity
                                 | 4: Only alert
                                 | 3: Alert and errors
                                 | 2: Alerts,errors and I/O operations
                                 | 1: Full verbosity)
                                . Default: 3
  -t  --triage            Triage mode (infinite run - scan every new file in
                          the input path directories). Default: false

Depending on where you are looking for files, FastFinder could be used with admin OR simple user rights.

Scan and export file match according to your needs

configuration examples are available there

input:
    path: [] # match file path AND / OR file name based on simple string 
    content:
        grep: [] # match literal string value inside file content
        yara: [] # use yara rule and specify rules path(s) for more complex pattern search (wildcards / regex / conditions) 
        checksum: [] # parse for md5/sha1/sha256 in file content 
options:
    contentMatchDependsOnPathMatch: true # if true, paths are a pre-filter for content searchs. If false, paths and content both generate matchs
    findInHardDrives: true	# enumerate hard drive content
    findInRemovableDrives: true # enumerate removable drive content 
    findInNetworkDrives: true # enumerate network drive content
    findInCDRomDrives: true # enumerate physical CD-ROM and mounted iso / vhd...
output:
    copyMatchingFiles: true # create a copy of every matching file
    base64Files: true # base64 matched content before copy
    filesCopyPath: '' # empty value will copy matched files in the fastfinder.exe folder
advancedparameters:
    yaraRC4Key: ''    # yara rules can be (un)/ciphered using the specified RC4 key
    maxScanFilesize: 2048 #  ignore files up to maxScanFileSize Mb (default: 2048)               
    cleanMemoryIfFileGreaterThanSize: 512 # clean fastfinder internal memory after heavy file scan (default: 512Mb) 

Search everywhere or in specified paths:

• use '?' in paths for simple char wildcard (eg. powershe??.exe)
• use '\*' in paths for multiple chars wildcard (eg. \*.exe)
• regular expressions are also available , just enclose paths with slashes (eg. /[0-9]{8}\.exe/)
• environment variables can also be used (eg. %TEMP%\myfile.exe)

Important notes

• input path are always case INSENSITIVE
• content search on string (grep) are always case SENSITIVE
• backslashes SHOULD NOT be escaped (except with regular expressions) For more informations, take a look at the examples

About this project

I initially created this project to automate fast system oriented IOC detection on a wide computer network. It fulfills the needs I have today. Nevertheless if you have complementary ideas, do not hesitate to ask for, I will see to implement them if they can be useful for everyone. On the other hand, pull request will be studied carefully.

Future releases

I don't plan to add any additional features right now. The next release will be focused on:

• Unit testing / Code testing coverage / CI
• Build more examples based on live malwares tradecraft and threat actor campaigns