Fast and customisable vulnerability scanner based on simple YAML based DSL.

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Nuclei is used to send requests across targets based on a template leading to zero false positives and providing fast scanning on large number of hosts. Nuclei offers scanning for a variety of protocols including TCP, DNS, HTTP, File, etc. With powerful and flexible templating, all kinds of security checks can be modelled with Nuclei.

We have a dedicated repository that houses various type of vulnerability templates contributed by more than 200 security researchers and engineers.

How it works

Install Nuclei

Nuclei requires go1.17 to install successfully. Run the following command to install the latest version -

go install -v github.com/projectdiscovery/nuclei/v2/cmd/nuclei@latest

More installation methods can be found here.

Nuclei Templates Nuclei has had built-in support for automatic template download/update as default since version v2.5.2. Nuclei-Templates project provides a community-contributed list of ready-to-use templates that is constantly updated. You may still use the update-templates flag to update the nuclei templates at any time; You can write your own checks for your individual workflow and needs following Nuclei's templating guide. The YAML DSL reference syntax is available here.

Usage

nuclei -h

This will display help for the tool. Here are all the switches it supports.

Nuclei is a fast, template based vulnerability scanner focusing
on extensive configurability, massive extensibility and ease of use.

Usage:
  nuclei [flags]

Flags:
TARGET:
   -u, -target string[]  target URLs/hosts to scan
   -l, -list string      path to file containing a list of target URLs/hosts to scan (one per line)

TEMPLATES:
   -t, -templates string[]  template or template directory paths to include in the scan
   -nt, -new-templates      run only new templates added in latest nuclei-templates release
   -w, -workflows string[]  workflow or workflow directory paths to include in the scan
   -validate                validate the passed templates to nuclei
   -tl                      list all available templates

FILTERING:
   -tags string[]                    execute a subset of templates that contain the provided tags
   -etags, -exclude-tags string[]    exclude templates with the provided tags
   -itags, -include-tags string[]    tags from the default deny list that permit executing more intrusive templates
   -et, -exclude-templates string[]  template or template directory paths to exclude
   -it, -include-templates string[]  templates to be executed even if they are excluded either by default or configuration
   -s, -severity value[]             Templates to run based on severity. Possible values - info,low,medium,high,critical
   -es, -exclude-severity value[]    Templates to exclude based on severity. Possible values - info,low,medium,high,critical
   -a, -author string[]              execute templates that are (co-)created by the specified authors

OUTPUT:
   -o, -output string            output file to write found issues/vulnerabilities
   -silent                       display findings only
   -nc, -no-color                disable output content coloring (ANSI escape codes)
   -json                         write output in JSONL(ines) format
   -irr, -include-rr             include request/response pairs in the JSONL output (for findings only)
   -nm, -no-meta                 don't display match metadata
   -nts, -no-timestamp           don't display timestamp metadata in CLI output
   -rdb, -report-db string       local nuclei reporting database (always use this to persist report data)
   -me, -markdown-export string  directory to export results in markdown format
   -se, -sarif-export string     file to export results in SARIF format

CONFIGURATIONS:
   -config string              path to the nuclei configuration file
   -rc, -report-config string  nuclei reporting module configuration file
   -H, -header string[]        custom headers in header:value format
   -V, -var value              custom vars in var=value format
   -r, -resolvers string       file containing resolver list for nuclei
   -sr, -system-resolvers      use system DNS resolving as error fallback
   -passive                    enable passive HTTP response processing mode
   -ev, -env-vars              enable environment variables support to be used in template
   -cc, -client-cert           client certificate file (PEM-encoded) used for authenticating against scanned hosts
   -ck, -client-key            client key file (PEM-encoded) used for authenticating against scanned hosts
   -ca, -client-ca             client certificate authority file (PEM-encoded) used for authenticating against scanned hosts

INTERACTSH:
   -iserver, -interactsh-server string  interactsh server url for self-hosted instance (default "https://interactsh.com")
   -itoken, -interactsh-token string    authentication token for self-hosted interactsh server
   -interactions-cache-size int         number of requests to keep in the interactions cache (default 5000)
   -interactions-eviction int           number of seconds to wait before evicting requests from cache (default 60)
   -interactions-poll-duration int      number of seconds to wait before each interaction poll request (default 5)
   -interactions-cooldown-period int    extra time for interaction polling before exiting (default 5)
   -ni, -no-interactsh                  disable interactsh server for OAST testing, exclude OAST based templates

RATE-LIMIT:
   -rl, -rate-limit int          maximum number of requests to send per second (default 150)
   -rlm, -rate-limit-minute int  maximum number of requests to send per minute
   -bs, -bulk-size int           maximum number of hosts to be analyzed in parallel per template (default 25)
   -c, -concurrency int          maximum number of templates to be executed in parallel (default 25)

OPTIMIZATIONS:
   -timeout int               time to wait in seconds before timeout (default 5)
   -retries int               number of times to retry a failed request (default 1)
   -mhe, -max-host-error int  max errors for a host before skipping from scan (default 30)
   -project                   use a project folder to avoid sending same request multiple times
   -project-path string       set a specific project path
   -spm, -stop-at-first-path  stop processing HTTP requests after the first match (may break template/workflow logic)
   -stream                    Stream mode - start elaborating without sorting the input

HEADLESS:
   -headless            enable templates that require headless browser support
   -page-timeout int    seconds to wait for each page in headless mode (default 20)
   -sb, -show-browser   show the browser on the screen when running templates with headless mode
   -sc, -system-chrome  Use local installed chrome browser instead of nuclei installed

DEBUG:
   -debug                    show all requests and responses
   -debug-req                show all sent requests
   -debug-resp               show all received responses
   -p, -proxy string[]       List of HTTP(s)/SOCKS5 proxy to use (comma separated or file input)
   -tlog, -trace-log string  file to write sent requests trace log
   -elog, -error-log string  file to write sent requests error log
   -version                  show nuclei version
   -v, -verbose              show verbose output
   -vv                       display templates loaded for scan
   -tv, -templates-version   shows the version of the installed nuclei-templates

UPDATE:
   -update                        update nuclei engine to the latest released version
   -ut, -update-templates         update nuclei-templates to latest released version
   -ud, -update-directory string  overwrite the default directory to install nuclei-templates
   -duc, -disable-update-check    disable automatic nuclei/templates update check

STATISTICS:
   -stats                    display statistics about the running scan
   -sj, -stats-json          write statistics data to an output file in JSONL(ines) format
   -si, -stats-interval int  number of seconds to wait between showing a statistics update (default 5)
   -m, -metrics              expose nuclei metrics on a port
   -mp, -metrics-port int    port to expose nuclei metrics on (default 9092)

Running Nuclei

Scanning target domain with community-curated nuclei templates.

nuclei -u https://example.com

Scanning target URLs with community-curated nuclei templates.

nuclei -list urls.txt

Example of urls.txt:

http://example.com
http://app.example.com
http://test.example.com
http://uat.example.com

More detailed examples of running nuclei can be found here.

For Security Engineers

Nuclei offers great number of features that are helpful for security engineers to customise workflow in their organisation. With the varieties of scan capabilities (like DNS, HTTP, TCP), security engineers can easily create their suite of custom checks with Nuclei.

• Varieties of protocols supported: TCP, DNS, HTTP, File, etc
• Achieve complex vulnerability steps with workflows and dynamic requests.
• Easy to integrate into CI/CD, designed to be easily integrated into regression cycle to actively check the fix and re-appearance of vulnerability.

For Bug Bounty hunters: Nuclei allows you to customise your testing approach with your own suite of checks and easily run across your bug bounty programs. Moreover, Nuclei can be easily integrated into any continuous scanning workflow. Designed to be easily integrated into other tool workflow. Can process thousands of hosts in few minutes. Easily automate your custom testing approach with our simple YAML DSL. Please check our other open-source projects that might fit into your bug bounty workflow: github.com/projectdiscovery, we also host daily refresh of DNS data at Chaos.

For Penetration Testers: Nuclei immensely improve how you approach security assessment by augmenting the manual, repetitive processes. Consultancies are already converting their manual assessment steps with Nuclei, it allows them to run set of their custom assessment approach across thousands of hosts in an automated manner. Pen-testers get the full power of our public templates and customization capabilities to speed-up their assessment process, and specifically with the regression cycle where you can easily verify the fix. Easily create your compliance, standards suite (e.g. OWASP Top 10) checklist. With capabilities like fuzz and workflows, complex manual steps and repetitive assessment can be easily automated with Nuclei. Easy to re-test vulnerability-fix by just re-running the template.

For Developers and Organisations

Nuclei is built with simplicity in mind, with the community backed templates by hundreds of security researchers, it allows you to stay updated with the latest security threats using continuous Nuclei scanning on the hosts. It is designed to be easily integrated into regression tests cycle, to verify the fixes and eliminate vulnerabilities from occurring in the future.

• CI/CD: Engineers are already utilising Nuclei within their CI/CD pipeline, it allows them to constantly monitor their staging and production environments with customised templates.
• Continuous Regression Cycle: With Nuclei, you can create your custom template on every new identified vulnerability and put into Nuclei engine to eliminate in the continuous regression cycle.

We have a discussion thread around this, there are already some bug bounty programs giving incentives to hackers on writing nuclei templates with every submission, that helps them to eliminate the vulnerability across all their assets, as well as to eliminate future risk in reappearing on productions. If you're interested in implementing it in your organisation, feel free to reach out to us. We will be more than happy to help you in the getting started process, or you can also post into the discussion thread for any help.

Resources

• Community Powered Scanning with Nuclei
• Nuclei Unleashed - Quickly write complex exploits
• Nuclei - Fuzz all the things
• Nuclei + Interactsh Integration for Automating OOB Testing
• Weaponizes nuclei Workflows to Pwn All the Things by @dwisiswant0
• How to Scan Continuously with Nuclei? by @dwisiswant0
• Hack with Automation !!! by @DhiyaneshGeek

Credits

Thanks to all the amazing community contributors for sending PRs. Do also check out the below similar open-source projects that may fit in your workflow:

FFuF, Qsfuzz, Inception, Snallygaster, Gofingerprint, Sn1per, Google tsunami, Jaeles, ChopChop

License

Nuclei is distributed under MIT License