😕 What the heck is a ferox anyway?
Ferox is short for Ferric Oxide. Ferric Oxide, simply put, is rust. The name rustbuster was taken, so I decided on a variation. 🤷
🤔 What's it do tho?
feroxbuster is a tool designed to perform Forced Browsing.
Forced browsing is an attack where the aim is to enumerate and access resources that are not referenced by the web application, but are still accessible by an attacker.
feroxbuster uses brute force combined with a wordlist to search for unlinked content in target directories. These resources may store sensitive information about web applications and operational systems, such as source code, credentials, internal network addressing, etc...
This attack is also known as Predictable Resource Location, File Enumeration, Directory Enumeration, and Resource Enumeration.
📖 Table of Contents
💿 Installation
Download a Release
Releases for multiple architectures can be found in the Releases section. The latest release for each of the following systems can be downloaded and executed as shown below.
Linux x86
curl -sLO https://github.com/epi052/feroxbuster/releases/latest/download/x86-linux-feroxbuster.zip
unzip x86-linux-feroxbuster.zip
chmod +x ./feroxbuster
./feroxbuster -V
Linux x86_64
curl -sLO https://github.com/epi052/feroxbuster/releases/latest/download/x86_64-linux-feroxbuster.zip
unzip x86_64-linux-feroxbuster.zip
chmod +x ./feroxbuster
./feroxbuster -V
MacOS x86_64
curl -sLO https://github.com/epi052/feroxbuster/releases/latest/download/x86_64-macos-feroxbuster.zip
unzip x86_64-macos-feroxbuster.zip
chmod +x ./feroxbuster
./feroxbuster -V
Windows x86
https://github.com/epi052/feroxbuster/releases/latest/download/x86-windows-feroxbuster.exe.zip
Expand-Archive .\feroxbuster.zip
.\feroxbuster\feroxbuster.exe -V
Windows x86_64
Invoke-WebRequest https://github.com/epi052/feroxbuster/releases/latest/download/x86_64-windows-feroxbuster.exe.zip -OutFile feroxbuster.zip
Expand-Archive .\feroxbuster.zip
.\feroxbuster\feroxbuster.exe -V
Homebrew on MacOS and Linux
Installable by Homebrew throughout own formulas:
🍏 MacOS
brew tap tgotwig/feroxbuster
brew install feroxbuster
🐧 Linux
brew tap tgotwig/linux-feroxbuster
brew install feroxbuster
Cargo Install
feroxbuster is published on crates.io, making it easy to install if you already have rust installed on your system.
cargo install feroxbuster
apt Install
Download feroxbuster_amd64.deb from the Releases section. After that, use your favorite package manager to install the .deb.
wget -sLO https://github.com/epi052/feroxbuster/releases/latest/download/feroxbuster_amd64.deb.zip
unzip feroxbuster_amd64.deb.zip
sudo apt install ./feroxbuster_amd64.deb
AUR Install
Install feroxbuster-git on Arch Linux with your AUR helper of choice:
yay -S feroxbuster-git
Docker Install
The following steps assume you have docker installed / setup
First, clone the repository.
git clone https://github.com/epi052/feroxbuster.git
cd feroxbuster
Next, build the image.
sudo docker build -t feroxbuster .
After that, you should be able to use docker run to perform scans with feroxbuster.
Basic usage
sudo docker run --init -it feroxbuster -u http://example.com -x js,html
Piping from stdin and proxying all requests through socks5 proxy
cat targets.txt | sudo docker run --net=host --init -i feroxbuster --stdin -x js,html --proxy socks5://127.0.0.1:9050
Mount a volume to pass in ferox-config.toml
You've got some options available if you want to pass in a config file. ferox-buster.toml can live in multiple locations and still be valid, so it's up to you how you'd like to pass it in. Below are a few valid examples:
sudo docker run --init -v $(pwd)/ferox-config.toml:/etc/feroxbuster/ferox-config.toml -it feroxbuster -u http://example.com
sudo docker run --init -v ~/.config/feroxbuster:/root/.config/feroxbuster -it feroxbuster -u http://example.com
Note: If you are on a SELinux enforced system, you will need to pass the :Z attribute also.
docker run --init -v (pwd)/ferox-config.toml:/etc/feroxbuster/ferox-config.toml:Z -it feroxbuster -u http://example.com
Define an alias for simplicity
alias feroxbuster="sudo docker run --init -v ~/.config/feroxbuster:/root/.config/feroxbuster -i feroxbuster"
⚙️ Configuration
Default Values
Configuration begins with with the following built-in default values baked into the binary:
- timeout:
7seconds - follow redirects:
false - wordlist:
/usr/share/seclists/Discovery/Web-Content/raft-medium-directories.txt - threads:
50 - verbosity:
0(no logging enabled) - statuscodes:
200 204 301 302 307 308 401 403 405 - useragent:
feroxbuster/VERSION - recursion depth:
4 - auto-filter wildcards -
true - output:
stdout
ferox-config.toml
After setting built-in default values, any values defined in a ferox-config.toml config file will override the
built-in defaults.
feroxbuster searches for ferox-config.toml in the following locations (in the order shown):
/etc/feroxbuster/(global)CONFIG_DIR/ferxobuster/(per-user)- The same directory as the
feroxbusterexecutable (per-user) - The user's current working directory (per-target)
CONFIG_DIRis defined as the following:
- Linux:
$XDG_CONFIG_HOMEor$HOME/.configi.e./home/bob/.config- MacOs:
$HOME/Library/Application Supporti.e./Users/bob/Library/Application Support- Windows:
{FOLDERID_RoamingAppData}i.e.C:\Users\Bob\AppData\Roaming
If more than one valid configuration file is found, each one overwrites the values found previously.
If no configuration file is found, nothing happens at this stage.
As an example, let's say that we prefer to use a different wordlist as our default when scanning; we can
set the wordlist value in the config file to override the baked-in default.
Notes of interest:
- it's ok to only specify values you want to change without specifying anything else
- variable names in
ferox-config.tomlmust match their command-line counterpart
# ferox-config.toml
= "/wordlists/jhaddix/all.txt"
A pre-made configuration file with examples of all available settings can be found in ferox-config.toml.example.
# ferox-config.toml
# Example configuration for feroxbuster
#
# If you wish to provide persistent settings to feroxbuster, rename this file to ferox-config.toml and make sure
# it resides in the same directory as the feroxbuster binary.
#
# After that, uncomment any line to override the default value provided by the binary itself.
#
# Any setting used here can be overridden by the corresponding command line option/argument
#
# wordlist = "/wordlists/jhaddix/all.txt"
# statuscodes = [200, 500]
# threads = 1
# timeout = 5
# proxy = "http://127.0.0.1:8080"
# verbosity = 1
# quiet = true
# output = "/targets/ellingson_mineral_company/gibson.txt"
# useragent = "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:47.0) Gecko/20100101 Firefox/47.0"
# redirects = true
# insecure = true
# extensions = ["php", "html"]
# norecursion = true
# addslash = true
# stdin = true
# dontfilter = true
# extract_links = true
# depth = 1
# sizefilters = [5174]
# queries = [["name","value"], ["rick", "astley"]]
# headers can be specified on multiple lines or as an inline table
#
# inline example
# headers = {"stuff" = "things"}
#
# multi-line example
# note: if multi-line is used, all key/value pairs under it belong to the headers table until the next table
# is found or the end of the file is reached
#
# [headers]
# stuff = "things"
# more = "headers"
Command Line Parsing
Finally, after parsing the available config file, any options/arguments given on the commandline will override any values that were set as a built-in or config-file value.
USAGE:
feroxbuster [FLAGS] [OPTIONS] --url <URL>...
FLAGS:
-f, --addslash Append / to each request
-D, --dontfilter Don't auto-filter wildcard responses
-e, --extract-links Extract links from response body (html, javascript, etc...); make new requests based on
findings (default: false)
-h, --help Prints help information
-k, --insecure Disables TLS certificate validation
-n, --norecursion Do not scan recursively
-q, --quiet Only print URLs; Don't print status codes, response size, running config, etc...
-r, --redirects Follow redirects
--stdin Read url(s) from STDIN
-V, --version Prints version information
-v, --verbosity Increase verbosity level (use -vv or more for greater effect)
OPTIONS:
-d, --depth <RECURSION_DEPTH> Maximum recursion depth, a depth of 0 is infinite recursion (default: 4)
-x, --extensions <FILE_EXTENSION>... File extension(s) to search for (ex: -x php -x pdf js)
-H, --headers <HEADER>... Specify HTTP headers (ex: -H Header:val 'stuff: things')
-o, --output <FILE> Output file to write results to (default: stdout)
-p, --proxy <PROXY> Proxy to use for requests (ex: http(s)://host:port, socks5://host:port)
-Q, --query <QUERY>... Specify URL query parameters (ex: -Q token=stuff -Q secret=key)
-S, --sizefilter <SIZE>... Filter out messages of a particular size (ex: -S 5120 -S 4927,1970)
-s, --statuscodes <STATUS_CODE>... Status Codes of interest (default: 200 204 301 302 307 308 401 403 405)
-t, --threads <THREADS> Number of concurrent threads (default: 50)
-T, --timeout <SECONDS> Number of seconds before a request times out (default: 7)
-u, --url <URL>... The target URL(s) (required, unless --stdin used)
-a, --useragent <USER_AGENT> Sets the User-Agent (default: feroxbuster/VERSION)
-w, --wordlist <FILE> Path to the wordlist
🧰 Example Usage
Multiple Values
Options that take multiple values are very flexible. Consider the following ways of specifying extensions:
./feroxbuster -u http://127.1 -x pdf -x js,html -x php txt json,docx
The command above adds .pdf, .js, .html, .php, .txt, .json, and .docx to each url
All of the methods above (multiple flags, space separated, comma separated, etc...) are valid and interchangeable. The same goes for urls, headers, status codes, queries, and size filters.
Include Headers
./feroxbuster -u http://127.1 -H Accept:application/json "Authorization: Bearer {token}"
Extract Links from Response Body (New in v1.1.0)
Search through the body of valid responses (html, javascript, etc...) for additional endpoints to scan. This turns
feroxbuster into a hybrid that looks for both linked and unlinked content.
Example request/response with --extract-links enabled:
- Make request to
http://example.com/index.html - Receive, and read in, the
bodyof the response - Search the
bodyfor absolute and relative links (i.e.homepage/assets/img/icons/handshake.svg) - Add the following directories for recursive scanning:
http://example.com/homepagehttp://example.com/homepage/assetshttp://example.com/homepage/assets/imghttp://example.com/homepage/assets/img/icons
- Make a single request to
http://example.com/homepage/assets/img/icons/handshake.svg
./feroxbuster -u http://127.1 --extract-links
IPv6, non-recursive scan with INFO-level logging enabled
./feroxbuster -u http://[::1] --norecursion -vv
Read urls from STDIN; pipe only resulting urls out to another tool
cat targets | ./feroxbuster --stdin --quiet -s 200 301 302 --redirects -x js | fff -s 200 -o js-files
Proxy traffic through Burp
./feroxbuster -u http://127.1 --insecure --proxy http://127.0.0.1:8080
Proxy traffic through a SOCKS proxy
./feroxbuster -u http://127.1 --proxy socks5://127.0.0.1:9050
Pass auth token via query parameter
./feroxbuster -u http://127.1 --query token=0123456789ABCDEF
🧐 Comparison w/ Similar Tools
There are quite a few similar tools for forced browsing/content discovery. Burp Suite Pro, Dirb, Dirbuster, etc... However, in my opinion, there are two that set the standard: gobuster and ffuf. Both are mature, feature-rich, and all-around incredible tools to use.
So, why would you ever want to use feroxbuster over ffuf/gobuster? In most cases, you probably won't. ffuf in particular can do the vast majority of things that feroxbuster can, while still offering boatloads more functionality. Here are a few of the use-cases in which feroxbuster may be a better fit:
- You want a simple tool usage experience
- You want to be able to run your content discovery as part of some crazy 12 command unix pipeline extravaganza
- You want to scan through a SOCKS proxy
- You want auto-filtering of Wildcard responses by default
- You want an integrated link extractor to increase discovered endpoints
- You want recursion along with some other thing mentioned above (ffuf also does recursion)
- You want a configuration file option for overriding built-in default values for your scans
| feroxbuster | gobuster | ffuf | |
|---|---|---|---|
| fast | ✔ | ✔ | ✔ |
| easy to use | ✔ | ✔ | |
| blacklist status codes (in addition to whitelist) | ✔ | ✔ | |
| allows recursion | ✔ | ✔ | |
| can specify query parameters | ✔ | ✔ | |
| SOCKS proxy support | ✔ | ||
| extracts links from response body to increase scan coverage | ✔ | ||
| multiple target scan (via stdin or multiple -u) | ✔ | ✔ | |
| configuration file for default value override | ✔ | ✔ | |
| can accept urls via STDIN as part of a pipeline | ✔ | ✔ | |
| can accept wordlists via STDIN | ✔ | ✔ | |
| filter by response size | ✔ | ✔ | |
| auto-filter wildcard responses | ✔ | ✔ | |
| performs other scans (vhost, dns, etc) | ✔ | ✔ | |
| time delay / rate limiting | ✔ | ✔ | |
| huge number of other options | ✔ |
Of note, there's another written-in-rust content discovery tool, rustbuster. I came across rustbuster when I was naming my tool (😢). I don't have any experience using it, but it appears to be able to do POST requests with an HTTP body, has SOCKS support, and has an 8.3 shortname scanner (in addition to vhost dns, directory, etc...). In short, it definitely looks interesting and may be what you're looking for as it has some capability I haven't seen in similar tools.
🤯 Common Problems/Issues (FAQ)
No file descriptors available
Why do I get a bunch of No file descriptors available (os error 24) errors?
There are a few potential causes of this error. The simplest is that your operating system sets an open file limit that is aggressively low. Through personal testing, I've found that 4096 is a reasonable open file limit (this will vary based on your exact setup).
There are quite a few options to solve this particular problem, of which a handful are shown below.
Increase the Number of Open Files
We'll start by increasing the number of open files the OS allows. On my Kali install, the default was 1024, and I know some MacOS installs use 256 😕.
Edit /etc/security/limits.conf
One option to up the limit is to edit /etc/security/limits.conf so that it includes the two lines below.
*represents all usershardandsoftindicate the hard and soft limits for the OSnofileis the number of open files option.
/etc/security/limits.conf
-------------------------
...
* soft nofile 4096
* hard nofile 8192
...
Use ulimit directly
A faster option, that is not persistent, is to simply use the ulimit command to change the setting.
ulimit -n 4096
Additional Tweaks (may not be needed)
If you still find yourself hitting the file limit with the above changes, there are a few additional tweaks that may help.
This section was shamelessly stolen from this stackoverflow answer. More information is included in that post and is recommended reading if you end up needing to use this section.
✨ Special thanks to HTB user @sparkla for their help with identifying these additional tweaks ✨
Increase the ephemeral port range, and decrease the tcp_fin_timeout.
The ephermal port range defines the maximum number of outbound sockets a host can create from a particular I.P. address. The fin_timeout defines the minimum time these sockets will stay in TIME_WAIT state (unusable after being used once). Usual system defaults are
net.ipv4.ip_local_port_range = 32768 61000net.ipv4.tcp_fin_timeout = 60
This basically means your system cannot consistently guarantee more than (61000 - 32768) / 60 = 470 sockets per second.
sudo sysctl net.ipv4.ip_local_port_range="15000 61000"
sudo sysctl net.ipv4.tcp_fin_timeout=30
Allow socket reuse while in a TIME_WAIT status
This allows fast cycling of sockets in time_wait state and re-using them. Make sure to read post Coping with the TCP TIME-WAIT from Vincent Bernat to understand the implications.
sudo sysctl net.ipv4.tcp_tw_reuse=1