Network Working Group                                          R. Pethia
Request for Comments: 1281                Software Engineering Institute
                                                              S. Crocker
                                       Trusted Information Systems, Inc.
                                                               B. Fraser
                                          Software Engineering Institute
                                                           November 1991

Guidelines for the Secure Operation of the Internet

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Preamble

   The purpose of this document is to provide a set of guidelines to aid
   in the secure operation of the Internet.  During its history, the
   Internet has grown significantly and is now quite diverse.  Its
   participants include government institutions and agencies, academic
   and research institutions, commercial network and electronic mail
   carriers, non-profit research centers and an increasing array of
   industrial organizations who are primarily users of the technology.
   Despite this dramatic growth, the system is still operated on a
   purely collaborative basis.  Each participating network takes
   responsibility for its own operation.  Service providers, private
   network operators, users and vendors all cooperate to keep the system
   functioning.

   It is important to recognize that the voluntary nature of the
   Internet system is both its strength and, perhaps, its most fragile
   aspect.  Rules of operation, like the rules of etiquette, are
   voluntary and, largely, unenforceable, except where they happen to
   coincide with national laws, violation of which can lead to
   prosecution.  A common set of rules for the successful and
   increasingly secure operation of the Internet can, at best, be
   voluntary, since the laws of various countries are not uniform
   regarding data networking.  Indeed, the guidelines outlined below
   also can be only voluntary.  However, since joining the Internet is
   optional, it is also fair to argue that any Internet rules of
   behavior are part of the bargain for joining and that failure to
   observe them, apart from any legal infrastructure available, are
   grounds for sanctions.

Introduction

   These guidelines address the entire Internet community, consisting of
   users, hosts, local, regional, domestic and international backbone
   networks, and vendors who supply operating systems, routers, network
   management tools, workstations and other network components.

   Security is understood to include protection of the privacy of
   information, protection of information against unauthorized
   modification, protection of systems against denial of service, and
   protection of systems against unauthorized access.

   These guidelines encompass six main points.  These points are
   repeated and elaborated in the next section.  In addition, a
   bibliography of computer and network related references has been
   provided at the end of this document for use by the reader.

Security Guidelines

   (1)  Users are individually responsible for understanding and
        respecting the security policies of the systems (computers and
        networks) they are using.  Users are individually accountable
        for their own behavior.

   (2)  Users have a responsibility to employ available security
        mechanisms and procedures for protecting their own data.  They
        also have a responsibility for assisting in the protection of
        the systems they use.

   (3)  Computer and network service providers are responsible for
        maintaining the security of the systems they operate.  They are
        further responsible for notifying users of their security
        policies and any changes to these policies.

   (4)  Vendors and system developers are responsible for providing
        systems which are sound and which embody adequate security
        controls.

   (5)  Users, service providers, and hardware and software vendors are
        responsible for cooperating to provide security.

   (6)  Technical improvements in Internet security protocols should be
        sought on a continuing basis.  At the same time, personnel
        developing new protocols, hardware or software for the Internet
        are expected to include security considerations as part of the
        design and development process.

Elaboration

   (1)  Users are individually responsible for understanding and
        respecting the security policies of the systems (computers and
        networks) they are using.  Users are individually accountable
        for their own behavior.

        Users are responsible for their own behavior.  Weaknesses in
        the security of a system are not a license to penetrate or
        abuse a system.  Users are expected to be aware of the security
        policies of computers and networks which they access and to
        adhere to these policies.  One clear consequence of this
        guideline is that unauthorized access to a computer or use of a
        network is explicitly a violation of Internet rules of conduct,
        no matter how weak the protection of those computers or networks.

        There is growing international attention to legal prohibition
        against unauthorized access to computer systems, and several
        countries have recently passed legislation that addresses the
        area (e.g., United Kingdom, Australia).  In the United States,
        the Computer Fraud and Abuse Act of 1986, Title 18 U.S.C.
        section 1030 makes it a crime, in certain situations, to access
        a Federal interest computer (federal government computers,
        financial institution computers, and a computer which is one of
        two or more computers used in committing the offense, not all of
        which are located in the same state) without authorization.
        Most of the 50 states in the U.S have similar laws.

        Another aspect of this part of the policy is that users are
        individually responsible for all use of resources assigned to
        them, and hence sharing of accounts and access to resources is
        strongly discouraged.  However, since access to resources is
        assigned by individual sites and network operators, the
        specific rules governing sharing of accounts and protection of
        access is necessarily a local matter.

   (2)  Users have a responsibility to employ available security
        mechanisms and procedures for protecting their own data.  They
        also have a responsibility for assisting in the protection of
        the systems they use.

        Users are expected to handle account privileges in a
        responsible manner and to follow site procedures for the
        security of their data as well as that of the system.  For
        systems which rely upon password protection, users should
        select good passwords and periodically change them.  Proper
        use of file protection mechanisms (e.g., access control lists)
        so as to define and maintain appropriate file access control

        is also part of this responsibility.

   (3)  Computer and network service providers are responsible for
        maintaining the security of the systems they operate.  They are
        further responsible for notifying users of their security
        policies and any changes to these policies.

        A computer or network service provider may manage resources on
        behalf of users within an organization (e.g., provision of
        network and computer services with a university) or it may
        provide services to a larger, external community (e.g., a
        regional network provider).  These resources may include host
        computers employed by users, routers, terminal servers, personal
        computers or other devices that have access to the Internet.

        Because the Internet itself is neither centrally managed nor
        operated, responsibility for security rests with the owners and
        operators of the subscriber components of the Internet.
        Moreover, even if there were a central authority for this
        infrastructure, security necessarily is the responsibility of
        the owners and operators of the systems which are the primary
        data and processing resources of the Internet.

        There are tradeoffs between stringent security measures at a
        site and ease of use of systems (e.g., stringent security
        measures may complicate user access to the Internet).  If a site
        elects to operate an unprotected, open system, it may be
        providing a platform for attacks on other Internet hosts while
        concealing the attacker's identity.  Sites which do operate
        open systems are nonetheless responsible for the behavior of
        the systems' users and should be prepared to render assistance
        to other sites when needed.  Whenever possible, sites should
        try to ensure authenticated Internet access.  The readers are
        directed to appendix A for a brief descriptive list of elements
        of good security.

        Sites (including network service providers) are encouraged to
        develop security policies.  These policies should be clearly
        communicated to users and subscribers.  The Site Security
        Handbook (FYI 8, RFC 1244) provides useful information and
        guidance on developing good security policies and procedures
        at both the site and network level.

   (4)  Vendors and system developers are responsible for providing
        systems which are sound and which embody adequate security
        controls.

        A vendor or system developer should evaluate each system in
        terms of security controls prior to the introduction of the
        system into the Internet community.  Each product (whether
        offered for sale or freely distributed) should describe the
        security features it incorporates.

        Vendors and system developers have an obligation to repair
        flaws in the security relevant portions of the systems they
        sell (or freely provide) for use in the Internet.  They are
        expected to cooperate with the Internet community in
        establishing mechanisms for the reporting of security flaws and
        in making security-related fixes available to the community in
        a timely fashion.

   (5)  Users, service providers, and hardware and software vendors are
        responsible for cooperating to provide security.

        The Internet is a cooperative venture.  The culture and
        practice in the Internet is to render assistance in security
        matters to other sites and networks.  Each site is expected to
        notify other sites if it detects a penetration in progress at
        the other sites, and all sites are expected to help one another
        respond to security violations.  This assistance may include
        tracing connections, tracking violators and assisting law
        enforcement efforts.

        There is a growing appreciation within the Internet community
        that security violators should be identified and held
        accountable.  This means that once a violation has been detected,
        sites are encouraged to cooperate in finding the violator and
        assisting in enforcement efforts.  It is recognized that many
        sites will face a trade-off between securing their sites as
        rapidly as possible versus leaving their site open in the hopes
        of identifying the violator.  Sites will also be faced with the
        dilemma of limiting the knowledge of a penetration versus
        exposing the fact that a penetration has occurred.  This policy
        does not dictate that a site must expose either its system or
        its reputation if it decides not to, but sites are encouraged
        to render as much assistance as they can.

   (6)  Technical improvements in Internet security protocols should be
        sought on a continuing basis.  At the same time, personnel
        developing new protocols, hardware or software for the Internet
        are expected to include security considerations as part of the
        design and development process.

        The points discussed above are all administrative in nature,
        but technical advances are also important.  Existing protocols

        and operating systems do not provide the level of security that
        is desired and feasible today.  Three types of advances are
        encouraged:

        (a)  Improvements should be made in the basic security
             mechanisms already in place.  Password security is
             generally poor throughout the Internet and can be
             improved markedly through the use of tools to administer
             password assignment and through the use of better
             authentication technology.  At the same time, the
             Internet user population is expanding to include a
             larger percentage of technically unsophisticated users.
             Security defaults on delivered systems and the controls
             for administering security must be geared to this growing
             population.

         (b)  Security extensions to the protocol suite are needed.
              Candidate protocols which should be augmented to improve
              security include network management, routing, file
              transfer, telnet, and mail.

         (c)  The design and implementation of operating systems should
              be improved to place more emphasis on security and pay
              more attention to the quality of the implementation of
              security within systems on the Internet.

APPENDIX A

   Five areas should be addressed in improving local security:

   (1)  There must be a clear statement of the local security policy,
        and this policy must be communicated to the users and other
        relevant parties.  The policy should be on file and available
        to users at all times, and should be communicated to users as
        part of providing access to the system.

   (2)  Adequate security controls must be implemented.  At a minimum,
        this means controlling access to systems via passwords,
        instituting sound password management, and configuring the
        system to protect itself and the information within it.

   (3)  There must be a capability to monitor security compliance and
        respond to incidents involving violation of security.  Logs of
        logins, attempted logins, and other security-relevant events
        are strongly advised, as well as regular audit of these logs.
        Also recommended is a capability to trace connections and other
        events in response to penetrations.  However, it is important
        for service providers to have a well thought out and published

        policy about what information they gather, who has access to it
        and for what purposes.  Maintaining the privacy of network
        users should be kept in mind when developing such a policy.

   (4)  There must be an established chain of communication and control
        to handle security matters.  A responsible person should be
        identified as the security contact.  The means for reaching the
        security contact should be made known to all users and should
        be registered in public directories, and it should be easy for
        computer emergency response centers to find contact information
        at any time.

        The security contact should be familiar with the technology and
        configuration of all systems at the site or should be able to
        get in touch with those who have this knowledge at any time.
        Likewise, the security contact should be pre-authorized to make
        a best effort to deal with a security incident, or should be
        able to contact those with the authority at any time.

   (5)  Sites and networks which are notified of security incidents
        should respond in a timely and effective manner.  In the case
        of penetrations or other violations, sites and networks should
        allocate resources and capabilities to identify the nature of
        the incident and limit the damage.  A site or network cannot be
        considered to have good security if it does not respond to
        incidents in a timely and effective fashion.

        If a violator can be identified, appropriate action should be
        taken to ensure that no further violations are caused.  Exactly
        what sanctions should be brought against a violator depend on
        the nature of the incident and the site environment.  For
        example, a university may choose to bring internal disciplinary
        action against a student violator.

        Similarly, sites and networks should respond when notified of
        security flaws in their systems.  Sites and networks have the
        responsibility to install fixes in their systems as they become
        available.

A Bibliography of Computer and Network Security Related Documents

United States Public Laws (PL) and Federal Policies

   [1] P.L. 100-235, "The Computer Security Act of 1987", (Contained in
       Appendix C of Citation No. 12, Vol II.), Jan. 8, 1988.

   [2] P.L. 99-474 (H.R. 4718), "Computer Fraud and Abuse Act of 1986",
       Oct. 16, 1986.

   [3] P.L. 99-508 (H.R. 4952), "Electronic Communications Privacy Act
       of 1986", Oct. 21, 1986.

   [4] P.L. 99-591, "Paperwork Reduction Reauthorization Act of 1986",
       Oct. 30, 1986.

   [5] P.L. 93-579, "Privacy Act of 1984", Dec. 31, 1984.

   [6] "National Security Decision Directive 145", (Contained in
       Appendix C of Citation No. 12, Vol II.).

   [7] "Security of Federal Automated Information Systems", (Contained
       in Appendix C of Citation No. 12, Vol II.), Appendix III of,
       Management of Federal Information Resources, Office of Management
       and Budget (OMB), Circular A-130.

   [8] "Protection of Government Contractor Telecommunications",
       (Contained in Appendix C of Citation No. 12, Vol II.), National
       Communications Security Instruction (NACSI) 6002.

Other Documents

   [9] Secure Systems Study Committee, "Computers at Risk: Safe
       Computing in the Information Age", Computer Science and
       Technology Board, National Research Council, 2101 Constitution
       Avenue, Washington, DC 20418, December 1990.

  [10] Curry, D., "Improving the Security of Your UNIX System", Report
       No. ITSTD-721-FR-90-21, SRI International, 333 Ravenswood Ave.,
       Menlo Park, CA, 94025-3493, April 1990.

  [11] Holbrook P., and J. Reynolds, Editors, "Site Security Handbook",
       FYI 8, RFC 1244, CICNet, ISI, July 1991.

  [12] "Industry Information Protection, Vols. I,II,III", Industry
       Information Security Task Force, President's National
       Telecommunications Advisory Committee, June 1988.

  [13] Jelen, G., "Information Security: An Elusive Goal", Report No.
       P-85-8, Harvard University, Center for Information Policy
       Research, 200 Akin, Cambridge, MA.  02138, June 1985.

  [14] "Electronic Record Systems and Individual Privacy", OTA-CIT-296,
       Congress of the United States, Office of Technology Assessment,
       Washington, D.C. 20510, June 1986.

  [15] "Defending Secrets, Sharing Data", OTA-CIT-310, Congress of the
       United States, Office of Technology Assessment, Washington, D.C.
       20510, October 1987.

  [16] "Summary of General Legislation Relating to Privacy and Computer
       Security", Appendix 1 of, COMPUTERS and PRIVACY: How the
       Government Obtains, Verifies, Uses and Protects Personal Data,
       GAO/IMTEC-90-70BR, United States General Accounting Office,
       Washington, DC 20548, pp.  36-40, August 1990.

  [17] Stout, E., "U.S. Geological Survey System Security Plan - FY
       1990", U.S. Geological Survey ISD, MS809, Reston, VA, 22092, May
       1990.

Security Considerations

   If security considerations had not been so widely ignored in the
   Internet, this memo would not have been possible.

Authors' Addresses

   Richard D. Pethia
   Software Engineering Institute
   Carnegie Mellon University
   Pittsburgh, Pennsylvania 15213-3890

   Phone:  (412) 268-7739
   FAX:    (412) 268-6989

   EMail:  rdp@cert.sei.cmu.edu

   Stephen D. Crocker
   Trusted Information Systems, Inc.
   3060 Washington Road
   Glenwood, Maryland 21738

   Phone:  (301) 854-6889
   FAX:    (301) 854-5363

   EMail:  crocker@tis.com

   Barbara Y. Fraser
   Software Engineering Institute
   Carnegie Mellon University
   Pittsburgh, Pennsylvania 15213-3890

   Phone:  (412) 268-5010
   FAX:    (412) 268-6989

   EMail:  byf@cert.sei.cmu.edu