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OWASP Logo OWASP Amass - Users' Guide

Network graph


Simple Examples For Getting Started

The amass tool and all the subcommands show options using the '-h' and '-help' flags:

amass -help

Check the version by performing the following:

amass -version

The most basic use of the tool for subdomain enumeration:

amass enum -d example.com

Typical parameters for DNS enumeration:

$ amass enum -v -src -ip -brute -min-for-recursive 2 -d example.com
[Google] www.example.com
[VirusTotal] ns.example.com
...

Executing the tool via the Docker image:

docker run -v OUTPUT_DIR_PATH:/.config/amass/ caffix/amass:latest enum --list

The volume argument allows the Amass graph database to persist between executions and output files to be accessed on the host system. The first field (left of the colon) of the volume option is the amass output directory that is external to Docker, while the second field is the path, internal to Docker, where amass will write the output files.

Command-line Usage Information

The amass tool has several subcommands shown below for handling your Internet exposure investigation.

Subcommand Description
intel Collect open source intelligence for investigation of the target organization
enum Perform DNS enumeration and network mapping of systems exposed to the Internet
viz Generate visualizations of enumerations for exploratory analysis
track Compare results of enumerations against common target organizations
db Manage the graph databases storing the enumeration results

Each subcommand has its own arguments that are shown in the following sections.

The 'intel' Subcommand

The intel subcommand can help you discover additional root domain names associated with the organization you are investigating. The data source sections of the configuration file are utilized by this subcommand in order to obtain passive intelligence, such as reverse whois information.

Flag Description Example
-active Enable active recon methods amass intel -active -addr 192.168.2.1-64 -p 80,443,8080
-addr IPs and ranges (192.168.1.1-254) separated by commas amass intel -addr 192.168.2.1-64
-asn ASNs separated by commas (can be used multiple times) amass intel -asn 13374,14618
-cidr CIDRs separated by commas (can be used multiple times) amass intel -cidr 104.154.0.0/15
-config Path to the INI configuration file amass intel -config config.ini
-d Domain names separated by commas (can be used multiple times) amass intel -whois -d example.com
-demo Censor output to make it suitable for demonstrations amass intel -demo -whois -d example.com
-df Path to a file providing root domain names amass intel -whois -df domains.txt
-dir Path to the directory containing the graph database amass intel -dir PATH -cidr 104.154.0.0/15
-ef Path to a file providing data sources to exclude amass intel -whois -ef exclude.txt -d example.com
-exclude Data source names separated by commas to be excluded amass intel -whois -exclude crtsh -d example.com
-if Path to a file providing data sources to include amass intel -whois -if include.txt -d example.com
-include Data source names separated by commas to be included amass intel -whois -include crtsh -d example.com
-ip Show the IP addresses for discovered names amass intel -ip -whois -d example.com
-ipv4 Show the IPv4 addresses for discovered names amass intel -ipv4 -whois -d example.com
-ipv6 Show the IPv6 addresses for discovered names amass intel -ipv6 -whois -d example.com
-list Print the names of all available data sources amass intel -list
-log Path to the log file where errors will be written amass intel -log amass.log -whois -d example.com
-max-dns-queries Maximum number of concurrent DNS queries amass intel -max-dns-queries 200 -whois -d example.com
-noresolvrate Disable resolver rate monitoring amass intel -cidr 104.154.0.0/15 -noresolvrate
-noresolvscore Disable resolver reliability scoring amass intel -cidr 104.154.0.0/15 -noresolvscore
-o Path to the text output file amass intel -o out.txt -whois -d example.com
-org Search string provided against AS description information amass intel -org Facebook
-p Ports separated by commas (default: 443) amass intel -cidr 104.154.0.0/15 -p 443,8080
-public-dns Use public-dns.info resolvers amass intel -cidr 104.154.0.0/15 -public-dns
-r IP addresses of preferred DNS resolvers (can be used multiple times) amass intel -r 8.8.8.8,1.1.1.1 -whois -d example.com
-rf Path to a file providing preferred DNS resolvers amass intel -rf data/resolvers.txt -whois -d example.com
-src Print data sources for the discovered names amass intel -src -whois -d example.com
-timeout Number of minutes to execute the enumeration amass intel -timeout 30 -d example.com
-whois All discovered domains are run through reverse whois amass intel -whois -d example.com

The 'enum' Subcommand

This subcommand will perform DNS enumeration and network mapping while populating the selected graph database. All the setting available in the configuration file are relevant to this subcommand. The following flags are available for configuration:

Flag Description Example
-active Enable active recon methods amass enum -active -d example.com -p 80,443,8080
-aw Path to a different wordlist file for alterations amass enum -aw PATH -d example.com
-bl Blacklist of subdomain names that will not be investigated amass enum -bl blah.example.com -d example.com
-blf Path to a file providing blacklisted subdomains amass enum -blf data/blacklist.txt -d example.com
-brute Perform brute force subdomain enumeration amass enum -brute -d example.com
-config Path to the INI configuration file amass enum -config config.ini
-d Domain names separated by commas (can be used multiple times) amass enum -d example.com
-demo Censor output to make it suitable for demonstrations amass enum -demo -d example.com
-df Path to a file providing root domain names amass enum -df domains.txt
-dir Path to the directory containing the graph database amass enum -dir PATH -d example.com
-do Path to data operations output file amass enum -do data.json -d example.com
-ef Path to a file providing data sources to exclude amass enum -ef exclude.txt -d example.com
-exclude Data source names separated by commas to be excluded amass enum -exclude crtsh -d example.com
-if Path to a file providing data sources to include amass enum -if include.txt -d example.com
-include Data source names separated by commas to be included amass enum -include crtsh -d example.com
-include-unresolvable Output DNS names that did not resolve amass enum -include-unresolvable -d example.com
-ip Show the IP addresses for discovered names amass enum -ip -d example.com
-ipv4 Show the IPv4 addresses for discovered names amass enum -ipv4 -d example.com
-ipv6 Show the IPv6 addresses for discovered names amass enum -ipv6 -d example.com
-json Path to the JSON output file amass enum -json out.json -d example.com
-list Print the names of all available data sources amass enum -list
-log Path to the log file where errors will be written amass enum -log amass.log -d example.com
-max-dns-queries Maximum number of concurrent DNS queries amass enum -max-dns-queries 200 -d example.com
-min-for-recursive Number of labels in a subdomain before recursive brute forcing amass enum -brute -min-for-recursive 3 -d example.com
-nf Path to a file providing already known subdomain names (from other tools/sources) amass enum -nf names.txt -d example.com
-noalts Disable generation of altered names amass enum -noalts -d example.com
-norecursive Turn off recursive brute forcing amass enum -brute -norecursive -d example.com
-noresolvrate Disable resolver rate monitoring amass enum -d example.com -noresolvrate
-noresolvscore Disable resolver reliability scoring amass enum -d example.com -noresolvscore
-o Path to the text output file amass enum -o out.txt -d example.com
-oA Path prefix used for naming all output files amass enum -oA amass_scan -d example.com
-passive A purely passive mode of execution amass enum --passive -d example.com
-p Ports separated by commas (default: 443) amass enum -d example.com -p 443,8080
-public-dns Use public-dns.info resolvers amass enum -d example.com -public-dns
-r IP addresses of preferred DNS resolvers (can be used multiple times) amass enum -r 8.8.8.8,1.1.1.1 -d example.com
-rf Path to a file providing preferred DNS resolvers amass enum -rf data/resolvers.txt -d example.com
-src Print data sources for the discovered names amass enum -src -d example.com
-timeout Number of minutes to execute the enumeration amass enum -timeout 30 -d example.com
-w Path to a different wordlist file amass enum -brute -w wordlist.txt -d example.com

The 'viz' Subcommand

Create enlightening network graph visualizations that add structure to the information gathered. This subcommand only leverages the 'output_directory' and remote graph database settings from the configuration file.

The files generated for visualization are created in the current working directory and named amass_TYPE

Switches for outputting the DNS and infrastructure findings as a network graph:

Flag Description Example
-config Path to the INI configuration file amass viz -config config.ini -d3
-d Domain names separated by commas (can be used multiple times) amass viz -d3 -d example.com
-d3 Output a D3.js v4 force simulation HTML file amass viz -d3 -d example.com
-df Path to a file providing root domain names amass viz -d3 -df domains.txt
-dir Path to the directory containing the graph database amass viz -d3 -dir PATH -d example.com
-enum Identify an enumeration via an index from the db listing amass viz -enum 1 -d3 -d example.com
-gexf Output to Graph Exchange XML Format (GEXF) amass viz -gephi -d example.com
-graphistry Output Graphistry JSON amass viz -graphistry -d example.com
-i Path to the Amass data operations JSON input file amass viz -d3 -d example.com
-maltego Output a Maltego Graph Table CSV file amass viz -maltego -d example.com
-visjs Output HTML that employs VisJS amass viz -visjs -d example.com

The 'track' Subcommand

Shows differences between enumerations that included the same target(s) for monitoring a target's attack surface. This subcommand only leverages the 'output_directory' and remote graph database settings from the configuration file. Flags for performing Internet exposure monitoring across the enumerations in the graph database:

Flag Description Example
-config Path to the INI configuration file amass track -config config.ini
-d Domain names separated by commas (can be used multiple times) amass track -d example.com
-df Path to a file providing root domain names amass track -df domains.txt
-dir Path to the directory containing the graph database amass track -dir PATH
-history Show the difference between all enumeration pairs amass track -history
-last The number of recent enumerations to include in the tracking amass track -last NUM
-since Exclude all enumerations before a specified date (format: 01/02 15:04:05 2006 MST) amass track -since DATE

The 'db' Subcommand

Performs viewing and manipulation of the graph database. This subcommand only leverages the 'output_directory' and remote graph database settings from the configuration file. Flags for interacting with the enumeration findings in the graph database include:

Flag Description Example
-config Path to the INI configuration file amass db -config config.ini
-d Domain names separated by commas (can be used multiple times) amass db -d example.com
-demo Censor output to make it suitable for demonstrations amass db -demo -d example.com
-df Path to a file providing root domain names amass db -df domains.txt
-dir Path to the directory containing the graph database amass db -dir PATH
-enum Identify an enumeration via an index from the listing amass db -enum 1 -show
-import Import an Amass data operations JSON file to the graph database amass db -import PATH
-ip Show the IP addresses for discovered names amass db -show -ip -d example.com
-ipv4 Show the IPv4 addresses for discovered names amass db -show -ipv4 -d example.com
-ipv6 Show the IPv6 addresses for discovered names amass db -show -ipv6 -d example.com
-list Print enumerations in the database and filter on domains specified amass db -list
-show Print the results for the enumeration index + domains provided amass db -show
-src Print data sources for the discovered names amass db -show -src -d example.com

The Output Directory

Amass has several files that it outputs during an enumeration (e.g. the log file). If you are not using a database server to store the network graph information, then Amass creates a file based graph database in the output directory. These files are used again during future enumerations, and when leveraging features like tracking and visualization.

By default, the output directory is created in the operating system default root directory to use for user-specific configuration data and named amass. If this is not suitable for your needs, then the subcommands can be instructed to create the output directory in an alternative location using the '-dir' flag.

If you decide to use an Amass configuration file, it will be automatically discovered when put in the output directory and named config.ini.

The Configuration File

You will need a config file to use your API keys with Amass. See the Example Configuration File for more details.

Amass automatically tries to discover the configuration file in the following locations:

Operating System Path
Linux / Unix $XDG_CONFIG_HOME/amass/config.ini or $HOME/.config/amass/config.ini
Windows %AppData%\amass\config.ini
OSX $HOME/Library/Application Support/amass/config.ini

These are good places for you to put your configuration file.

Note that these locations are based on the output directory. If you use the -dir flag, the location where Amass will try to discover the configuration file will change. For example, if you pass in -dir ./my-out-dir, Amass will try to discover a configuration file in ./my-out-dir/config.ini.

Default Section

Option Description
mode Determines which mode the enumeration is performed in: default, passive or active
output_directory The directory that stores the graph database and other output files
maximum_dns_queries The maximum number of concurrent DNS queries that can be performed
include_unresolvable When set to true, causes DNS names that did not resolve to be printed

The network_settings Section

Option Description
address IP address or range (e.g. a.b.c.10-245) that is in scope
asn ASN that is in scope
cidr CIDR (e.g. 192.168.1.0/24) that is in scope
port Specifies a port to be used when actively pulling TLS certificates

The domains Section

Option Description
domain A root DNS domain name to be added to the enumeration scope

The resolvers Section

Option Description
resolver The IP address of a DNS resolver and used globally by the amass package
public_dns_resolvers Incorporate public-dns.info resolvers into the enumeration
score_resolvers Toggle resolver reliability scoring
monitor_resolver_rate Toggle resolver rate monitoring

The blacklisted Section

Option Description
subdomain A DNS subdomain name to be considered out of scope during the enumeration

The disabled_data_sources Section

Option Description
data_source One of the Amass data sources that is not to be used during the enumeration

The gremlin Section

Option Description
url URL in the form of "ws://host:port" where Amass will connect to a TinkerPop database
username User of the TinkerPop database server that can access the Amass graph database
password Valid password for the user identified by the 'username' option

The bruteforce Section

Option Description
enabled When set to true, brute forcing is performed during the enumeration
recursive When set to true, brute forcing is performed on discovered subdomain names as well
minimum_for_recursive Number of discoveries made in a subdomain before performing recursive brute forcing
wordlist_file Path to a custom wordlist file to be used during the brute forcing

The alterations Section

Option Description
enabled When set to true, permuting resolved DNS names is performed during the enumeration
minimum_for_word_flip Number of times a word must be seen before using it for future word flips and word additions
edit_distance Number of times an edit operation will be performed on a name sample during fuzzy label searching
flip_words When set to true, causes words in DNS names to be exchanged for others in the alteration word list
flip_numbers When set to true, causes numbers in DNS names to be exchanged for other numbers
add_words When set to true, causes other words in the alteration word list to be added to resolved DNS names
add_numbers When set to true, causes numbers to be added and removed from resolved DNS names
wordlist_file Path to a custom wordlist file that provides additional words to the alteration word list

Data Source Sections

Each Amass data source service can have a dedicated configuration file section. The section is named just as in the output from the 'amass enum -list' command.

This is how data sources can be configured that have authentication requirements.

Option Description
apikey The API key to be used when accessing the data source
secret An additional secret to be used with the API key
username User for the data source account
password Valid password for the user identified by the 'username' option

The Graph Database

All Amass enumeration findings are stored in a graph database. This database is either located in a single file within the output directory or connected to remotely using settings provided by the configuration file.

When a new enumeration begins and a graph database already exists with previous findings for the same target(s), the subdomain names from those previous enumerations are utilized in the new enumeration. New DNS queries are performed against those subdomain names to ensure that they are still legitimate and to obtain current IP addresses.

The results from each enumeration is stored separately in the graph database, which allows the tracking subcommand to look for differences across the enumerations and provide the user with highlights about the target.

There is nothing preventing multiple users from sharing a single (remote) graph database and leveraging each others findings across enumerations.

Importing OWASP Amass Results into Maltego

  1. Convert the Amass data into a Maltego graph table CSV file:
amass viz -maltego
  1. Import the CSV file with the correct Connectivity Table settings:

Connectivity table

  1. All the Amass findings will be brought into your Maltego Graph:

Maltego results

Integrating OWASP Amass into Your Work

If you are using the amass package within your own Go code, be sure to properly seed the default pseudo-random number generator:

package main

import (
	"fmt"
	"math/rand"
	"time"

	"github.com/OWASP/Amass/v3/config"
	"github.com/OWASP/Amass/v3/enum"
	"github.com/OWASP/Amass/v3/services"
)

func main() {
	// Seed the default pseudo-random number generator
	rand.Seed(time.Now().UTC().UnixNano())

	sys, err := services.NewLocalSystem(config.NewConfig())
	if err != nil {
		return
	}

	e := enum.NewEnumeration(sys)
	if e == nil {
		return
	}

	go func() {
		for result := range e.Output {
			fmt.Println(result.Name)
		}
	}()

	// Setup the most basic amass configuration
	e.Config.AddDomain("example.com")
	e.Start()
}

In case you get an error saying "Failed to create the graph", try changing the output directory in the config:

cfg := config.NewConfig()
cfg.Dir = "/tmp"

sys, err := services.NewLocalSystem(cfg)
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