Beta Unofficial
`security.txt` Spec

Motivation and Prior Work

Many security researchers encounter situations where they are unable to responsibly disclose security issues to companies because there is no course of action laid out or no way indicated to contact the owner of a particular resource.

As per section 4 of {{?RFC2142}}, there is an existing convention of using the <SECURITY@domain> email address for communications regarding security issues. That convention provides only a single, email-based channel of communication for security issues per domain, and does not provide a way for domain owners to publish information about their security disclosure policies.

There are also contact conventions prescribed for Internet Service Providers (ISPs) in section 2 of {{?RFC3013}}, for Computer Security Incident Response Teams (CSIRTs) in section 3.2 of {{?RFC2350}} and for site operators in section 5.2 of {{?RFC2196}}. As per {{?RFC7485}}, there is also contact information provided by Regional Internet Registries (RIRs) and domain registries for owners of IP addresses, autonomous system numbers (ASNs) and domain names. However, none of these address the issue of how security researchers can locate disclosure policies and contact information for companies in order to responsibly disclose security issues.

In this document, we define a richer, machine-parsable and more extensible way for companies to communicate information about their security disclosure policies, which is not limited to email and also allows for additional features such as encryption. This standard is designed to help assist with the security disclosure process by making it easier for companies to designate the preferred steps for researchers to take when trying to reach out to them with security issues.

Terminology

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in BCP 14 {{!RFC2119}} {{!RFC8174}} when, and only when, they appear in all capitals, as shown here.

Note to Readers

Note to the RFC Editor: Please remove this section prior to publication.

Development of this draft takes place on Github at: https://github.com/securitytxt/security-txt

A mailing list is available for discussion at: https://www.freelists.org/list/securitytxt

The Specification

This standard defines a text file to be placed in a known location that provides information for security researchers to assist in disclosing security issues.

The file is named “security.txt”, and this file SHOULD be placed under the /.well-known/ path (”/.well-known/security.txt”) {{!RFC5785}} of a domain name or IP address for web properties. If it is not possible to place the security.txt file in the /.well-known/ path or setup a redirect, web-based services MAY place the file in the top-level path of a given web domain or IP address (”/security.txt”) as a fall back option. For web-based services, the instructions MUST be accessible via the Hypertext Transfer Protocol {{!RFC1945}} as a resource of Internet Media Type “text/plain” with the default charset parameter set to “utf-8” per section 4.1.3 of {{!RFC2046}}. For file systems and version control repositories a “.security.txt” file SHOULD be placed in the root directory of a particular file system or source code project.

This text file contains multiple directives with different values. The “directive” is the first part of a field all the way up to the colon (“Contact:”). Directives MUST be case-insensitive. The “value” comes after the directive (“https://example.com/security”). A “field” MUST always consist of a directive and a value (“Contact: https://example.com/security”). A security.txt file can have an unlimited number of fields. It is important to note that you MUST have a separate line for every field. One MUST NOT chain multiple values for a single directive and everything MUST be in a separate field. Unless otherwise indicated in a definition of a particular field, any directive MAY appear multiple times.

Scope

A “security.txt” file MUST only apply to the domain in the URI used to retrieve it, not to any of its subdomains or parent domains. A “security.txt” file that is found in a file system or version control repository MUST only apply to the folder or repository in which it is located, and not to any of its parent or sibling folders, or repositories.

Some examples appear below:

# The following only applies to example.com.
https://example.com/.well-known/security.txt

# This only applies to subdomain.example.com.
https://subdomain.example.com/.well-known/security.txt

# This security.txt file applies to IPv4 address of 192.0.2.0.
http://192.0.2.0/.well-known/security.txt

# This security.txt file applies to IPv6 address of 2001:db8:8:4::2.
http://[2001:db8:8:4::2]/.well-known/security.txt

# This security.txt file applies to the /example/folder1 directory.
/example/folder1/security.txt

Comments

Any line beginning with the “#” (%x30) symbol MUST be interpreted as a comment.

Example:

# This is a comment.

You MAY use one or more comments as descriptive text immediately before the field. Parsers SHOULD associate the comments with the respective field.

Separate Fields

A separate line is REQUIRED for every new value and field. You MUST NOT chain everything into a single field. Every line MUST end either with a carriage return and line feed characters (CRLF / %x0D %x0A) or just a line feed character (LF / %x0A).

Field Definitions

Acknowledgments {#acknowledgments}

This directive allows you to link to a page where security researchers are recognized for their reports. The page being linked to SHOULD list individuals or companies that disclosed security vulnerabilities and worked with you to remediate the issue.

Example:

Acknowledgments: https://example.com/hall-of-fame.html

Example security acknowledgments page:

We would like to thank the following researchers:

(2017-04-15) Frank Denis - Reflected cross-site scripting
(2017-01-02) Alice Quinn  - SQL injection
(2016-12-24) John Buchner - Stored cross-site scripting
(2016-06-10) Anna Richmond - A server configuration issue

Contact {#contact}

This directive allows you to provide an address that researchers SHOULD use for reporting security issues. The value MAY be an email address, a phone number and/or a contact page with more information. The “Contact:” directive MUST always be present in a security.txt file. If this directive indicates a web URL, then it MUST begin with “https://”. Security email addresses SHOULD use the conventions defined in section 4 of {{!RFC2142}}, but there is no requirement for this directive to be an email address.

The value MUST follow the general syntax described in {{!RFC3986}}. This means that “mailto” and “tel” URI schemes MUST be used when specifying email addresses and telephone numbers.

The precedence SHOULD be in listed order. The first field is the preferred method of contact. In the example below, the e-mail address is the preferred method of contact.

Contact: mailto:security@example.com
Contact: tel:+1-201-555-0123
Contact: https://example.com/security-contact.html

Encryption {#encryption}

This directive allows you to point to an encryption key that security researchers SHOULD use for encrypted communication. You MUST NOT directly add your key to the field, instead the value of this field MUST be a URI pointing to a location where the key can be retrieved from. If this directive indicates a web URL, then it MUST be begin with “https://”.

When it comes to verifying the authenticity of the key, it is always the security researcher’s responsibility to make sure the key being specified is indeed one they trust. Researchers MUST NOT assume that this key is used to generate the signature file referenced in {{!signature}}.

Example of a PGP key available from a web server:

Encryption: https://example.com/pgp-key.txt

Example of a PGP key available from an OPENPGPKEY DNS:

Encryption: dns:5d2d37ab76d47d36._openpgpkey.example.com?type=OPENPGPKEY

Example of a PGP key being referenced by its fingerprint:

Encryption: openpgp4fpr:5f2de5521c63a801ab59ccb603d49de44b29100f

Hiring {#hiring}

The “Hiring” directive is used for linking to the vendor’s security-related job positions. If this directive indicates a web URL, then it SHOULD be begin with “https://”.

Hiring: https://example.com/jobs.html

Permission {#permission}

The presence of the “Permission” directive is used to indicate to security researchers that they MUST NOT perform any kind of testing against the resource hosting the “security.txt” file. This field MUST have a value which is REQUIRED to be set to the string “none”. Other values MUST NOT be used. This field MUST NOT appear more than once.

The absence of the “Permission” directive or the use of any other value other than “none” for this directive MUST NOT be interpreted by researchers as being granted permission to test the resource. Additionally, the presence or absence of this directive MUST NOT be interpreted as having any legal value.

Example:

Permission: none

Policy {#policy}

This directive allows you to link to where your security policy and/or disclosure policy is located. This can help security researchers understand what you are looking for and how to report security vulnerabilities. If this directive indicates a web URL, then it SHOULD begin with “https://”.

Example:

Policy: https://example.com/security-policy.html

Signature {#signature}

This directive allows you to specify a full URI (as per {{!RFC3986}}) of an external signature file that can be used to check the authenticity of a “security.txt” file. External signature files SHOULD be named “security.txt.sig” and SHOULD be placed under the /.well-known/ path (”/.well-known/security.txt.sig”). If this directive indicates a web URL, then it MUST be begin with “https://”. This directive MUST NOT appear more than once.

It is RECOMMENDED to implementers that this directive always be used.

When it comes to verifying the authenticity of the file, it is always the security researcher’s responsibility to make sure the key being specified is indeed one they trust.

Here is an example of an external signature file.

Signature: https://example.com/.well-known/security.txt.sig

Example of a “security.txt” file

# Our security address
Contact: mailto:security@example.com

# Our PGP key
Encryption: https://example.com/pgp-key.txt

# Our security policy
Policy: https://example.com/security-policy.html

# Our security acknowledgments page
Acknowledgments: https://example.com/hall-of-fame.html

# Verify this security.txt file
Signature: https://example.com/.well-known/security.txt.sig

Location of the security.txt file

                          External
+----------------------------------------------------------------+
|              Default                                           |
|  +-----------------------------+          +-----------------+  |
|  |                             | Redirect |                 |  |
|  |  /.well-known/security.txt  <----------+  /security.txt  |  |
|  |                             |          |                 |  |
|  +-----------------------------+          +-----------------+  |
|                                                                |
+----------------------------------------------------------------+

        Internal
+------------------------+
|                        |
|  +------------------+  |
|  |                  |  |
|  |  /.security.txt  |  |
|  |                  |  |
|  +------------------+  |
|                        |
+------------------------+

Web-based services

Web-based services SHOULD place the security.txt file under the /.well-known/ path; e.g. https://example.com/.well-known/security.txt. A security.txt file located under the top-level path SHOULD either redirect (as per section 6.4 of {{!RFC7231}}) to the security.txt file under the /.well-known/ path or be used as a fall back.

Filesystems

File systems SHOULD place the security.txt file under the root directory; e.g., /.security.txt, C:.security.txt.

user:/$ l
.security.txt
example-directory-1/
example-directory-2/
example-directory-3/
example-file

Internal hosts

A .security.txt file SHOULD be placed in the root directory of an internal host.

Extensibility {#extensibility}

Like many other formats and protocols, this format may need to be extended over time to fit the ever-changing landscape of the Internet. Therefore, extensibility is provided via an IANA registry for directives as defined in {{registry}}. Any directives registered via that process MUST be considered optional. To encourage extensibility and interoperability, implementors MUST ignore any fields they do not explicitly support.

File Format Description and ABNF Grammar

The expected file format of the security.txt file is plain text (MIME type “text/plain”) as defined in section 4.1.3 of {{!RFC2046}} and is encoded using UTF-8 {{!RFC3629}} in Net-Unicode form {{!RFC5198}}.

The following is an ABNF definition of the security.txt format, using the conventions defined in {{!RFC5234}} and {{!RFC5322}}.

body                   = *line (permission-field eol) (signature-field eol) *line

line                   = *1(field / comment) eol

eol                    = *WSP [CR] LF

field                  = acknowledgments-field /
                         contact-field /
                         encryption-field /                         
                         hiring-field /
                         policy-field /
                         ext-field

fs                     = ":"

comment                = "#" *(WSP / VCHAR / %xA0-E007F)

acknowledgments-field  = "Acknowledgments" fs SP uri

contact-field          = "Contact" fs SP (email / uri / phone)

email                  = <Email address as per {{!RFC5322}}>

phone                  = "+" *1(DIGIT / "-" / "(" / ")" / SP)

uri                    = <URI as per {{!RFC3986}}>

encryption-field       = "Encryption" fs SP uri

hiring-field           = "Hiring" fs SP uri

permission-field       = "Permission" fs SP "none"

policy-field           = "Policy" fs SP uri

signature-field        = "Signature" fs SP uri

ext-field              = field-name fs SP unstructured

field-name             = <as per section 3.6.8 of {{!RFC5322}}>

unstructured           = <as per section 3.2.5 of {{!RFC5322}}>

“ext-field” refers to extension fields, which are discussed in {{extensibility}}

Security considerations

Organizations creating security.txt files will need to consider several security-related issues. These include exposure to sensitive information and attacks where limited access to a server could grant the ability to modify the contents of the security.txt file or affect how it is served. Organizations SHOULD also monitor their security.txt files regularly to detect tampering. Organizations SHOULD also ensure that any resources such as web pages, email addresses and telephone numbers references by a “security.txt” file are kept current, are accessible and controlled by the organization, and are kept secure.

To ensure the authenticity of the security.txt file, organizations SHOULD sign the file and include the signature using the “Signature” directive ({{signature}}). As stated in {{encryption}} and {{signature}}, both encryption keys and external signature files MUST be loaded over HTTPS.

Websites SHOULD reserve the security.txt namespace to ensure no third-party can create a page with the “security.txt” name.

IANA Considerations

example.com is used in this document following the uses indicated in {{?RFC2606}}.

192.0.2.0 and 2001:db8:8:4::2 are used in this document following the uses indicated in {{?RFC6890}}.

Well-Known URIs registry

The “Well-Known URIs” registry should be updated with the following additional values (using the template from {{?RFC5785}}):

URI suffix: security.txt

URI suffix: security.txt.sig

Change controller: IETF

Specification document(s): this document

Registry for security.txt Header Fields {#registry}

IANA is requested to create the “security.txt Header Fields” registry in accordance with {{?RFC8126}}. This registry will contain header fields for use in security.txt files, defined by this specification.

New registrations or updates MUST be published in accordance with the “Expert Review” guidelines as described in section 4.5 of {{?RFC8126}}. Any new field thus registered is considered optional by this specification unless a new version of this specification is published.

New registrations and updates MUST contain the following information:

  1. Name of the field being registered or updated
  2. Short description of the field
  3. Whether the field can appear more than once
  4. The document in which the specification of the field is published
  5. New or updated status, which MUST be one of: current: The field is in current use deprecated: The field is in current use, but its use is discouraged historic: The field is no longer in current use

An update may make a notation on an existing registration indicating that a registered field is historical or deprecated if appropriate.

The initial registry contains these values:

   Field Name: Acknowledgments
   Description: link to page where security researchers are recognized
   Multiple Appearances: Yes
   Published in: this document
   Status: current

   Field Name: Contact
   Description: contact information to use for reporting security issues
   Multiple Appearances: Yes
   Published in: this document
   Status: current

   Field Name: Encryption
   Description: link to a key to be used for encrypted communication
   Multiple Appearances: Yes
   Published in: this document
   Status: current

   Field Name: Hiring
   Description: link to the vendor's security-related job positions
   Multiple Appearances: Yes
   Published in: this document
   Status: current

   Field Name: Permission
   Description: indicates that researchers MUST NOT do any testing
   Multiple Appearances: No
   Published in: this document
   Status: current

   Field Name: Policy
   Description: link to security policy page
   Multiple Appearances: Yes
   Published in: this document
   Status: current

   Field Name: Signature
   Description: signature used to verify the authenticity of the file
   Multiple Appearances: No
   Published in: this document
   Status: current

Contributors

The authors would like to acknowledge the help provided during the development of this document by Tom Hudson, Joel Margolis, Jobert Abma, Gerben Janssen van Doorn, Austin Heap, Justin Calmus, and Casey Ellis.

The authors would also like to acknowledge the feedback provided by multiple members of IETF’s SAAG and SEC-DISPATCH lists.

— back

Note to Readers

Note to the RFC Editor: Please remove this section prior to publication.

Development of this draft takes place on Github at https://github.com/securitytxt/security-txt

Document History

Note to the RFC Editor: Please remove this section prior to publication.

Since draft-foudil-securitytxt-00

  • Moved to use IETF’s markdown tools for draft updates
  • Added table of contents and a fuller list of references
  • Moved file to .well-known URI and added IANA registration (#3)
  • Added extensibility with an IANA registry for fields (#34)
  • Added text explaining relationship to RFC 2142 / security@ email address (#25)
  • Scope expanded to include internal hosts, domains, IP addresses and file systems
  • Support for digital signatures added (#19)

The full list of changes can be viewed via the IETF document tracker: https://tools.ietf.org/html/draft-foudil-securitytxt-01

Since draft-foudil-securitytxt-01

  • Added appendix with pointer to Github and document history
  • Added external signature file to the well known URI registry (#59)
  • Added policy field (#53)
  • Added diagram explaining the location of the file on public vs. internal systems
  • Added recommendation that external signature files should use HTTPS (#55)
  • Added recommendation that organizations should monitor their security.txt files (#14)

The full list of changes can be viewed via the IETF document tracker: https://tools.ietf.org/html/draft-foudil-securitytxt-02

Since draft-foudil-securitytxt-02

  • Use “mailto” and “tel” (#62)
  • Fix typo in the “Example” section (#64)
  • Clarified that the root directory is a fall back option (#72)
  • Defined content-type for the response (#68)
  • Clarify the scope of the security.txt file (#69)
  • Cleaning up text based on the NITS tools suggestions (#82)
  • Added clarification for newline values
  • Clarified the encryption field language, added examples of DNS-stored encryption keys (#28 and #94)
  • Added “Hiring” field

Since draft-foudil-securitytxt-03

  • Added “Hiring” field to the registry section
  • Added an encryption example using a PGP fingerprint (#107)
  • Added reference to the mailing list (#111)
  • Added a section referencing related work (#113)
  • Fixes for idnits (#82)
  • Changing some references to informative instead of normative
  • Adding “Permission” field (#30)
  • Fixing remaining ABNF issues (#83)
  • Additional editorial changes and edits

Full list of changes can be viewed via the IETF document tracker: https://tools.ietf.org/html/draft-foudil-securitytxt