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Network Working Group                                        K. Moriarty
Internet-Draft                                           EMC Corporation
Intended status: Informational                                 A. Morton
Expires: September 8, 2015                                     AT&T Labs
                                                           March 7, 2015

                    Effect of Ubiquitous Encryption


   Increased use of encryption will impact operations for security and
   network management causing a shift in how these functions are
   performed.  In some cases, new methods to both monitor and protect
   data will evolve.  In more drastic circumstances, the ability to
   monitor may be eliminated.  This draft includes a collection of
   current security and network management functions that may be
   impacted by the shift to increased use of encryption.  This draft
   does not attempt to solve these problems, but rather document the
   current state to assist in the development of alternate options to
   achieve the intended purpose of the documented practices.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 8, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Network Service Provider Monitoring . . . . . . . . . . . . .   5
     2.1.  Middlebox Monitoring  . . . . . . . . . . . . . . . . . .   5
       2.1.1.  Traffic Analysis Fingerprinting . . . . . . . . . . .   5
       2.1.2.  Traffic Surveys . . . . . . . . . . . . . . . . . . .   6
       2.1.3.  Deep Packet Inspection (DPI)  . . . . . . . . . . . .   6
     2.2.  Network Monitoring for Performance Management and
           Troubleshooting . . . . . . . . . . . . . . . . . . . . .   7
     2.3.  Inter Data Center Encryption  . . . . . . . . . . . . . .   7
       2.3.1.  new section . . . . . . . . . . . . . . . . . . . . .   7
   3.  Encryption in Hosting SP Environments . . . . . . . . . . . .   8
     3.1.  Management Access Security  . . . . . . . . . . . . . . .   8
       3.1.1.  Customer Access Monitoring  . . . . . . . . . . . . .   8
       3.1.2.  Application SP Content Monitoring . . . . . . . . . .   9
     3.2.  Hosted Applications . . . . . . . . . . . . . . . . . . .  10
       3.2.1.  Monitoring needs for Managed Applications . . . . . .  10
       3.2.2.  Mail Service Providers  . . . . . . . . . . . . . . .  11
       3.2.3.  Code Repositories . . . . . . . . . . . . . . . . . .  12
       3.2.4.  Document Management . . . . . . . . . . . . . . . . .  12
     3.3.  Data Storage  . . . . . . . . . . . . . . . . . . . . . .  12
       3.3.1.  Host-level Encryption . . . . . . . . . . . . . . . .  12
       3.3.2.  Disk Encryption, Data at Rest . . . . . . . . . . . .  13
       3.3.3.  Cross Data Center Replication Services  . . . . . . .  14
     3.4.  new section . . . . . . . . . . . . . . . . . . . . . . .  14
   4.  Encryption for Enterprise Users . . . . . . . . . . . . . . .  15
     4.1.  Monitoring Needs of the Enterprise  . . . . . . . . . . .  15
     4.2.  Techniques for Monitoring Internet Session Traffic  . . .  16
   5.  Encryption for Home Users . . . . . . . . . . . . . . . . . .  17
   6.  Security Monitoring for Specific Attack Types . . . . . . . .  17
     6.1.  Mail Abuse and SPAM . . . . . . . . . . . . . . . . . . .  17
     6.2.  Denial of Service . . . . . . . . . . . . . . . . . . . .  18
     6.3.  Phishing  . . . . . . . . . . . . . . . . . . . . . . . .  18
     6.4.  Botnets . . . . . . . . . . . . . . . . . . . . . . . . .  19
     6.5.  eCrime  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     6.6.  Malware . . . . . . . . . . . . . . . . . . . . . . . . .  20
     6.7.  Blocklists  . . . . . . . . . . . . . . . . . . . . . . .  20
     6.8.  [Any other subsections to be contributed?]  . . . . . . .  20
   7.  Response to Increased Encryption and Looking Forward  . . . .  20
   8.  Operational Monitoring  . . . . . . . . . . . . . . . . . . .  21

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   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  21
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  22
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  22
     12.2.  Informative References . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   In response to pervasive monitoring revelations and the IETF
   consensus that Pervasive Monitoring is an Attack [RFC7258], efforts
   are underway to increase encryption of Internet traffic.  Session
   encryption helps to prevent both passive and active attacks on
   transport protocols, with pervasive monitoring being primarily a
   passive attack.  The Internet Architecture Board (IAB) released a
   statement advocating for increased use of encryption in November
   2014.  Views on acceptable encryption have also shifted and are
   documented in "Opportunistic Security" (OS) [RFC7435], where
   cleartext sessions should be upgraded to unauthenticated session
   encryption, rather than no encryption.  OS encourages upgrading from
   cleartext, but cannot require or guarantee such upgrades.  Once OS is
   used, it allows for an upgrade to authenticated encryption.  These
   efforts are necessary to improve end users expectation of privacy,
   making pervasive monitoring cost prohibitive.  Active attacks are
   still possible on sessions where unauthenticated sessions are in use.

   The push for ubiquitous encryption via OS is specific to improving
   privacy for everyday users of the Internet.  Many attackers and those
   that pose a greater threat are already using strong encryption and
   tools like TOR [TOR] to prevent active attacks from on their data

   Although there is a push for OS, there is also work being done to
   improve implementation development and configuration flaws of TLS and
   DTLS sessions to prevent active attacks used to monitor or intercept
   session data.  The (UTA) working group is in process of publishing
   documentation to improve the security of TLS and DTLS sessions.  They
   have documented the known attack vectors in
   [I-D.ietf-uta-tls-attacks] and have documented Best Practices for TLS
   and DTLS in [I-D.ietf-uta-tls-bcp].

   Current estimates of session encryption approximate that about 30% of
   web sites have session encryption enabled, according to the
   Electronic Frontier Foundation [EFF].  The Mozilla Foundation
   maintains statistics on SSL/TLS usage and as of March 2015, 64% of
   HTTP transactions are encrypted.  Enterprise networks such as EMC
   observe that about 78% of outbound employee traffic was encrypted in

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   June 2014.  Although the actual number of sites may only be around
   30%, they include some of the most visited sites on the Internet for
   corporate users.

   In addition to encrypted web site access (TLS over HTTP), other
   application level transport encryption efforts are underway.  This
   includes a push to encrypt session transport for mail (SMTP - gateway
   to gateway) and other protocols such as instant messaging (TLS over
   XMPP).  Although this does provide protection from passive
   wiretapping [RFC4949] attacks, the servers could be a point of
   vulnerability if user-to-user encryption is not provided for these
   messaging protocols.  User-to-user content encryption schemes, such
   as S/MIME and PGP for email and Off-the-Record (OTR) for Extensible
   Messaging and Presence Protocol (XMPP) are used by those interested
   to protect their data as it crosses intermediary servers, preventing
   the vulnerability described by providing an end-to-end solution.
   User-to-user schemes are under review and additional options will
   emerge to ease the configuration requirements, making this type of
   option more accessible to non-technical users interested in
   protecting their privacy.

   Increased use of encryption (either opportunistic or authenticated)
   will impact operations for security and network management causing a
   shift in how these functions are performed.  In some cases new
   methods to monitor and protect data will evolve, for other cases the
   need may be eliminated.  This draft includes a collection of current
   security and network management functions that may be impacted by
   this shift to increased use of encryption.  This draft does not
   attempt to solve these problems, but rather document the current
   state to assist in the development of alternate options to achieve
   the intended purpose of the documented practices.

   In this document we consider several different forms of service
   providers, so we distinguish between them with adjectives.  For
   example, network service providers (or network operators) provide IP-
   packet transport primarily, though they may bundle other services
   with packet transport.  Alternatively, application service providers
   primarily offer systems that participate as an end-point in
   communications with the application user, and hosting service
   providers lease computing, storage, and communications systems in
   datacenters.  In practice, many companies perform two or more service
   provider roles, but may be historically associated with one.

   [Contributions are welcome to expand the list of documented

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2.  Network Service Provider Monitoring

   Network Service Providers (SP) are responding to encryption on the
   Internet, some helping to increase the use of encryption and others
   preventing its use.  Network SPs for this definition include the
   backbone Internet Service providers as well as those providing
   infrastructure at scale for core Internet use (hosted infrastructure
   and services such as email).

   Following the Snowden revelations, application service providers
   responded by encrypting traffic between their data centers to prevent
   passive monitoring from taking place unbeknownst to the providers
   (Yahoo, Google, etc.).  Large mail service providers also began to
   encrypt session transport to hosted mail services.  This had an
   immediate impact to help protect the privacy of users data, but
   created a problem for network operators.  They could no longer gain
   access to session streams resulting in actions by several to regain
   their operational practices that require cleartext data sessions.

   The EFF reported several network service providers taking steps to
   prevent the use of TLS over SMTP by breaking StartTLS, preventing the
   negotiation process resulting in fallback to the use of clear text.
   The use of encryption prevents middle boxes from performing functions
   that range from load balancing to monitoring for attacks or enabling
   "lawful intercept" in the US [CALEA].  Some of these practices may be
   on the decline now that they are exposed through the media, but they
   are representative of the struggles administrators will have with
   changes in their ability to monitor and manage traffic.

2.1.  Middlebox Monitoring

   Network service providers use various monitoring techniques for
   security and operational purposes.  The following subsections detail
   the purpose of each type of monitoring and what protocol fields are
   used to accomplish the task.

2.1.1.  Traffic Analysis Fingerprinting

   Fingerprinting is used in traffic analysis and monitoring to identify
   traffic streams that match certain patterns.  This technique may be
   used with clear text or encrypted sessions.  Some Distributed Denial
   of Service (DDoS) prevention techniques at the Network SP level rely
   on the ability to fingerprint traffic in order to mitigate the effect
   of this type of attack.  Thus, fingerprinting may be an aspect of an
   attack or part of attack countermeasures.

   The first/obvious trigger for DDoS mitigation is uncharacteristic
   traffic volume and/or congestion at various points associated with

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   the attackee's communications.  One approach to mitigate such an
   attack involves distinguishing attacker traffic from legitimate user
   traffic through analysis.  The ability to examine layers and payloads
   above transport provides a new range of filtering opportunities at
   each layer in the clear.  Fewer layers are in the clear means reduced
   filtering opportunities to mitigate attacks.

   Traffic analysis fingerprinting could also be used on web traffic to
   perform passive monitoring and invade privacy.

   For example, browser fingerprints are comprised of many
   characteristics, including User Agent, HTTP Accept headers, browser
   plug-in details, screen size and color details, system fonts and time
   zone.  [PANO] will audit these details for users.  A monitoring
   system could easily identify a specific browser, and by correlating
   other information, identify a specific user.

2.1.2.  Traffic Surveys

   Internet traffic surveys are useful in many well-intentioned
   pursuits, such as CAIDA data [CAIDA] and SP network design and
   optimization.  Tracking the trends in Internet traffic growth, from
   earlier peer-to-peer communication to the extensive adoption of
   unicast video streaming applications, has required a view of traffic
   composition and reports with acceptable accuracy.  As application
   designers and network operators both continue to seek optimizations,
   the role of traffic surveys from passive monitoring grows in

   Passive monitoring makes inferences about observed traffic using the
   maximal information available, and is subject to inaccuracies
   stemming from incomplete sampling (of packets in a stream) or loss
   due to monitoring system overload.  When encryption conceals more
   layers in each packet, reliance on pattern inferences and other
   heuristics grows, and accuracy suffers.  For example, the traffic
   patterns between server and browser are dependent on browser supplier
   and version, even when the sessions use the same server application
   (e.g., web e-mail access).  It remains to be seen whether more
   complex inferences can be mastered to produce the same monitoring

2.1.3.  Deep Packet Inspection (DPI)

   The features and efficiency of some Internet services can be
   augmented through analysis of user flows and the applications they
   provide.  For example, network caching of popular content at a
   location close to the requesting user can improve delivery
   efficiency, and authorized parties use DPI in combination with

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   content distribution networks to determine if they can intervene
   effectively.  Encryption of packet contents at a given protocol layer
   usually makes inspection of that layer and higher layers impossible,
   as well as DPI processing at the formerly clear text layers.

2.2.  Network Monitoring for Performance Management and Troubleshooting

   Similar to DPI, the performance of some services can be more
   efficiently managed and repaired when information on user
   transactions is available to the service provider.  It may be
   possible to continue such monitoring activities without clear text
   access to the application layers of interest, but inaccuracy will
   increase and efficiency of repair activities will decrease.  Also,
   there may be more cases of user communication failures when the
   additional encryption processes are introduced, leading to more
   customer service contacts and (at the same time) less information
   available to network operations repair teams.

   [Types of network and performance monitoring used by IP-level service
   providers should be discussed here.  How does encryption impact their
   current techniques?  What do they use in data streams to maintain
   expected service levels?]

   With the growing use of WebSockets [RFC6455], many forms of
   communications (from isochronous/real-time to bulk/elastic file
   transfer) will take place over HTTP port 80, so only the messages and
   higher-layer data will make application differentiation possible.  If
   the monitoring systems sees only "HTTP port 443", it cannot
   distinguish application streams that would benefit from priority
   queueing from others that would not.  In short, systems that invoked
   policies for the user's benefit are rendered less-effective (or in-
   effective) by encryption of information they once viewed easily.

2.3.  Inter Data Center Encryption

   The use of encryption at an IP-level between data centers of large
   application service providers has increased as a result of
   revelations that governments were passively monitoring these
   connections.  [How has security and operations monitoring of these
   session been impacted or has that been fully addressed and how?
   Storage section contains one example that fits this scenario.]

2.3.1.  new section

   [Needs for monitoring from an operational perspective could be in
   subsections to this bullet, contributions welcome to understand and
   document the struggle to determine alternate approaches in subsequent

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   efforts.  This should include specific monitoring goals as well as
   what is currently used to achieve those goals - how and why.]

3.  Encryption in Hosting SP Environments

   Hosted environments have had varied requirements in the past for
   encryption, with many businesses choosing to use these services
   primarily for data and applications that are not business or privacy
   sensitive.  A shift prior to the revelations on surveillance/passive
   monitoring began where businesses were asking for hosted environments
   to provide higher levels of security so that additional applications
   and service could be hosted externally.  Businesses understanding the
   threats of monitoring in hosted environments only increased that
   pressure to provide more secure access and session encryption to
   protect the management of hosted environments as well as for the data
   and applications.

3.1.  Management Access Security

   Hosted environments may have multiple levels of management access,
   where some may be strictly for the Hosting SP (infrastructure that
   may be shared among customers) and some may be accessed by a specific
   customer for application management.  In some cases, there are
   multiple levels of hosting service providers, further complicating
   the security of management infrastructure and the associated

   Hosting service provider management access is typically segregated
   from other traffic with a control channel and may or may not be
   encrypted depending upon the isolation characteristics of the
   management session.  Customer access may be through a dedicated
   connection, but this is becoming less common with newer hosted
   service models leveraging the Internet.

3.1.1.  Customer Access Monitoring

   Hosted applications that allow some level of customer management
   access may also require monitoring by the hosting service provider.
   The monitoring needs could include access control restrictions such
   as authentication, authorization, and accounting for filtering and
   firewall rules to ensure they are continuously met.  Customer access
   may occur on multiple levels, including user-level and administrative
   access.  The hosting service provider may need to monitor access
   either through session monitoring or log evaluation to ensure
   security service level agreements (SLA) for access management are
   met.  The use of session encryption to access hosted environments
   will limit the ability to use session data to ensure access

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   restrictions are maintained.  Monitoring and filtering may occur at

   2-tuple  IP-level with source and destination IP addresses alone, or

   5-tuple  IP and protocol-level with source IP address, destination IP
      address, protocol number, source port number, and destination port

   Session encryption at the application level, TLS for example,
   currently allows access to the 5-tuple.  IP-level encryption, such as
   IPsec in tunnel mode prevents access to the 5-tuple and may limit the
   ability to restrict traffic via filtering techniques.  This shift may
   not impact all hosting service provider solutions as alternate
   controls may be used to authenticate sessions or access may require
   that mobile clients access such services by first connecting to the
   organization before accessing the hosted application.  Shifts in
   access may be required to maintain equivalent access control
   management.  Logs may also be used for monitoring access control
   restrictions are met, but would be limited to the data that could be
   observed due to encryption at the point of log generation.  Log
   analysis is out of scope for this document.

   Intrusion detection, performance, availability, [What else should be
   covered in this section?]

3.1.2.  Application SP Content Monitoring

   Application Service Providers may offer content-level monitoring
   options to detect intellectual property leakage, or other attacks.
   The use of session encryption will prevent Data Leakage Protection
   (DLP) used on the session streams from accessing content to search on
   keywords or phases to detect such leakage.  DLP is often used to
   prevent the leakage of Personally Identifiable Information (PII) as
   well as financial account information, Personal Health Information
   (PHI), and Payment Card Information (PCI).  If session encryption is
   terminated at a gateway prior to accessing these services, DLP on
   session data can still be performed.  The decision of where to
   terminate encryption to hosted environments will be a risk decision
   made between the application service provider and customer
   organization according to their priorities.  DLP can be performed at
   the server for the hosted application and on an end users system in
   an organization as alternate or additional monitoring points of
   content, however is not frequently done in a service provider

   [What other monitoring is specific to SP Applications?  This likely
   includes monitoring equipment, change control processing,

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   configuration monitoring, security control compliance, performance,
   availability, OAM, etc.  A number of the possibilities within these
   brackets may occur within the SP environment and may or may not be
   impacted by the push for encryption.  With increasingly security
   applications moving to hosted environments, tenant isolation may
   require use of encryption inside of the data center.  Should we
   discuss that here so the impact is understood and what monitoring
   performed today is documented?]

3.2.  Hosted Applications

   Organizations are increasingly using hosted applications rather than
   in house solutions that require maintenance of equipment and
   software.  Examples include Enterprise Resource Planning (ERP)
   solutions, payroll service, time and attendance, travel and expense
   reporting among others.  Organizations may require some level of
   management access to these hosted applications and will typically
   require session encryption or a dedicated channel for this activity.

   In other cases, hosted applications may be fully managed by a hosting
   service provider with service level agreement expectations for
   availability and performance as well as for security functions
   including malware detection.

3.2.1.  Monitoring needs for Managed Applications

   Performance, availability, and other SLA requirements, etc.  [What
   monitoring is done by these SPs, why, and what do they monitor?  Can
   this section cover the operational aspect for each of the offerings
   listed below, or do they need to be broken out by service?]

   Performance, availability, and other aspects of a SLA are often
   collected through passive monitoring.  For example:

   o  Availability: ability to establish connections with hosts to
      access applications, and discern the difference between network or
      host-related causes of unavailability.

   o  Performance: ability to complete transactions within a target
      response time, and discern the difference between network or host-
      related causes of excess response time.

   Here, as with all passive monitoring, the accuracy of inferences are
   dependent on the cleartext information available, and encryption
   would tend to reduce the information and therefore, the accuracy.

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3.2.2.  Mail Service Providers

   Mail (application) service providers vary in what services they
   offer.  Options may include a fully hosted solution where mail is
   stored external to an organization's environment on mail service
   provider equipment or the service offering may be limited to monitor
   incoming mail to remove SPAM [Section 6.1], malware [Section 6.6],
   and phishing attacks [Section 6.3] before mail is directed to the
   organization's equipment.  In both of these cases, content of the
   messages and headers is monitored to detect SPAM, malware, phishing,
   and other messages that may be considered an attack.

   In addition to the monitoring needs for specific attack types
   discussed in Section 6, mail service providers [Need descriptions for
   other types of monitoring performed.  What is used now in their
   monitoring?  How will use of TLS between servers impact their ability
   to monitor for security or operations?  Users have no idea if the TLS
   covers their entire session stream or if it's left in clear text over
   some of the hops in this hop-by-hop protection - does this matter and
   how does it impact monitoring or do monitoring needs lead to this
   problem (broken STARTTLS negotiations)?

   Many efforts are emerging to improve user-to-user encryption to
   protect end user's privacy.  Some of these efforts involve encryption
   of email header information such as the message subject.  Mail system
   operators could still find enough helpful information in the rest of
   the header fields if the subject was no longer accessible, however it
   could reduce effectiveness of administrators.  In some cases,
   administrators may search on mail systems for known subject fields of
   abuse messages from inboxes or mail queues to remove phishing or
   other messages that contain malware or links to malware.  Their
   ability to perform prevention may be more limited with full
   deployment of end-to-end mail encryption with header fields
   inaccessible.  The header fields [RFC2822] used most often in their
   operational work include:

   o  Subject: - may be considered privacy sensitive

   o  To:/From: - may be considered privacy sensitive

   o  Received: from

   o  Date:

   o  Sent:

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3.2.3.  Code Repositories

   Intrusion detection, performance, availability, malware detection,
   etc.  [What monitoring is done by these SPs, why, and what do they

3.2.4.  Document Management

   Intrusion detection, performance, availability, malware detection,
   etc.  [What monitoring is done by these SPs, why, and what do they

3.3.  Data Storage

   Numerous service offerings exist that provide hosted storage
   solutions.  This section describes the various offerings and details
   the monitoring for each type of service and how encryption may impact
   the operational and security monitoring performed.

   Trends in data storage encryption for hosted environments include a
   range of options.  The following list is intentionally high-level to
   describe the types of encryption used in coordination with data
   storage that may be hosted remotely, meaning the storage is
   physically located in an external data center requiring transport
   over the Internet.  Options for monitoring will vary with both
   approaches from what may be done today.

3.3.1.  Host-level Encryption

   For higher security and/or privacy of data and applications, options
   that provide end-to-end encryption of the data from the users desktop
   or server to the storage platform may be preferred.  With this
   description, host level encryption includes any solution that
   encrypts data at the object level, not transport.  Encryption of data
   may be performed with libraries on the system or at the application
   level, which includes file encryption services via a file manager.
   Host-level encryption is useful when data storage is hosted or when
   in scenarios when storage location is determined based on capacity or
   based on a set of parameters to automate decisions.  This could mean
   that large data sets accessed infrequently could be sent to an off-
   site storage platform at an external hosting service, data accessed
   frequently may be stored locally, or decision could be based on the
   transaction type.  Host-level encryption is grouped separately for
   the purpose of this document as the monitoring needs as this data is
   bursted to off-site storage platforms, where traffic crosses the
   Internet are similar.  If session encryption is used, the protocol is
   likely to be TLS.

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   The general monitoring needs of hosted storage solutions that use
   host-level (object) encryption is described in this subsection.
   Solutions might include backup services and external storage
   services, such as those that burst data that exceeds internal limits
   on occasion to external storage platforms operated by a third party.

   Monitoring of data flows to hosted storage solutions is performed for
   security and operational purposes.  The security monitoring may be to
   detect anomalies in the data flows that could include changes to
   destination, the amount of data transferred, or alterations in the
   size and frequency of flows.  Operational considerations include
   capacity and availability monitoring.

   [What is monitored in the flows?  What data is monitored when the
   sessions are encrypted vs. when session encryption is not in use?
   Note that object encryption may not be used in all cases.]  Backup Storage

   [This is a placeholder in case there are distinct monitoring needs
   for any of the options that fall into this category.  Backup Storage
   is listed as an example, but will be removed if there are no
   monitoring needs that needs to be discussed at a more granular level
   than the general description.]

3.3.2.  Disk Encryption, Data at Rest

   There are multiple ways to achieve full disk encryption for stored
   data.  Encryption may be performed on data to be stored while in
   transit close to the storage media with solutions like Controller
   Based Encryption (CBE) or in the drive system with Self-Encrypting
   Drives (SED).  Session encryption is typically coupled with
   encryption of these data at rest (DAR) solutions to also protect data
   in transit.  Transport encryption is likely via TLS.  Monitoring Session Flows for DAR Solutions

   The general monitoring needs for transport of data to storage
   platforms, where object level encryption is performed close to or on
   the storage platform are similar to those described in the section on
   Monitoring for Hosted Storage.  The primary difference for these
   solutions is the possible exposure of sensitive information, which
   could include privacy related data, financial information, or
   intellectual property if session encryption via TLS is not deployed.
   Session encryption is typically used with these solutions, but that
   decision would be based on a risk assessment.  There are use cases

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   where DAR or disk-level encryption is required.  Examples include
   preventing exposure of data if physical disks are stolen or lost as
   data is decrypted upon access when that access is from the expected
   and configured application or service.

   [What is monitored in the flows?  What data is monitored when the
   sessions are encrypted vs. when session encryption is not in use?
   There is obvious exposure of data when session encryption is not in
   use and session monitoring is not necessarily limited to the 5-tuple.
   Contributions welcome from those that have knowledge of what is
   actually used in monitoring of these sessions.]

3.3.3.  Cross Data Center Replication Services

   Storage services also include data replication which may occur
   between data centers and may leverage Internet connections to tunnel
   traffic.  The traffic may use iSCSI [RFC7143] or FC/IP [RFC7146]
   encapsulated in IPsec.  Either transport or tunnel mode may be used
   for IPsec depending upon the termination points of the IPsec session,
   if it is from the storage platform itself or from a gateway device at
   the edge of the data center respectively.  Monitoring Of IPSec for Data Replication Services

   The general monitoring needs for data replication are described in
   this subsection.

   Monitoring of data flows between data centers may be performed for
   security and operational purposes and would typically concentrate
   more on the operational needs since these flows are essentially
   virtual private networks (VPN) between data centers.  Operational
   considerations include capacity and availability monitoring
   [Contributions to expand this description and the more detailed data
   used for analysis below is welcome.].  The security monitoring may be
   to detect anomalies in the data flows, similar to what was described
   in the "Monitoring for Hosted Storage Section".

   [What is monitored in the flows?  What data is monitored when the
   sessions are encrypted vs. when session encryption is not in use?
   Note that object encryption may not be used in all cases.]

3.4.  new section

   [Did we miss anything that should go here?]

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4.  Encryption for Enterprise Users

   This section is limited to the use of encryption by enterprise users
   to the Internet and not that of internal enterprise networks.  To
   date, there is not yet demand to encrypt internal networks, with the
   exception of sensitive data and applications and those that require
   encryption through regulatory requirements.

4.1.  Monitoring Needs of the Enterprise

   Enterprise users are subject to the policies of their organization.
   As such, proxies may be in use to:

   1.  intercept outbound session traffic to monitor for intellectual
       property leakage (by users or more likely these days through
       malware and trojans),

   2.  detect viruses/malware entering the network via email or web

   3.  detect malware/Trojans in action, possibly connecting to remote

   4.  detect attacks (Cross site scripting and other common web related

   5.  track misuse and abuse by employees,

   6.  restrict the types of protocols permitted to/from the corporate

   7.  assess traffic volume on a per-application basis, for billing,
       capacity planning, optimization of geographical location for
       servers or proxies, and other needs,

   8.  assess performance in terms of application response time and user
       perceived response time, and

   9.  re-direct to requests to caches of popular or bandwidth-intensive
       Internet content.

   For each type of monitoring, different techniques and parts of the
   data stream may be necessary.  As we transition to an increased use
   of encryption that is increasingly harder to break, alternate methods
   of monitoring for operational purposes will be necessary to prevent
   the need to break encryption and thus privacy of users (which may not
   apply in a corporate setting by policy).

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4.2.  Techniques for Monitoring Internet Session Traffic

   Corporate networks commonly monitor outbound session traffic to
   detect or prevent attacks as well as to guarantee service level
   expectations.  In some cases, alternate options are available when
   encryption is in use, but techniques like that of data leakage
   prevention tools at a proxy would not be possible if encrypted
   traffic can not be intercepted, thus requiring alternate options to

   Data leakage detection prevention (DLP) tools intercept traffic at
   the Internet gateway or proxy services with the ability to man-in-
   the-middle (MiTM) encrypted session traffic (HTTP/TLS).  These tools
   may use key words important to the enterprise including business
   sensitive information such as trade secrets, financial data,
   personally identifiable information (PII), or personal health
   information (PHI).  Various techniques are used to intercept HTTP/TLS
   sessions for DLP and other purposes, and are described in
   "Summarizing Known Attacks on TLS and DTLS"
   [I-D.ietf-uta-tls-attacks].  Note: many corporate policies allow
   access to personal financial and other sites for users without

   Monitoring traffic patterns for anomalous behavior such as increased
   flows of traffic that could be bursty at odd times or flows to
   unusual destinations (small or large amounts of traffic).  This
   traffic may or may not be encrypted and various methods of encryption
   or just obfuscation may be used.

   Restrictions on traffic to approved sites: Web proxies are sometimes
   used to filter traffic, allowing only access to well-known sites
   known to be legitimate and free of malware on last check by a proxy
   service company.  This type of restriction is usually not noticeable
   in a corporate setting, but may be to those in research who could
   access colleagues individual sites or new web sites that have not yet
   been screened.  In situations where new sites are required for
   access, they can typically be added after notification by the user or
   proxy log alerts and review.  Home mail account access may be blocked
   in corporate settings to prevent another vector for malware to enter
   as well as for intellectual property to leak out of the network.
   This method remains functional with increased use of encryption and
   may be more effective at preventing malware from entering the
   network.  Web proxy solutions monitor and potentially restrict access
   based on the destination URL or the DNS name.  A complete URL may be
   used in cases where access restrictions vary for content on a
   particular site or for the sites hosted on a particular server.

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   Desktop DLP tools are used in some corporate environments as well.
   Since these tools reside on the desktop, they can intercept traffic
   before it is encrypted and may provide a continued method of
   monitoring intellectual property leakage from the desktop to the
   Internet or attached devices.

   DLP tools can also be deployed by Network Service providers, as they
   have the unique and efficient vantage point of monitoring all traffic
   paired with destinations off the enterprise network.  This makes an
   effective solution for enterprises that allow "bring-you-own" devices
   and devices that do not fit the desktop category, but are used on
   corporate networks nonetheless.

   Enterprises may wish to reduce the traffic on their Internet access
   facilities by monitoring requests for within-policy content and
   caching it.  In this case, repeated requests for Internet content
   spawned by URLs in e-mail trade newsletters or other sources can be
   served within the enterprise network.  Gradual deployment of end to
   end encryption would tend to reduce the cacheable content over time,
   owing to concealment of critical headers and payloads.  Many forms of
   enterprise performance management and optimization based on
   monitoring (DPI) would suffer the same fate.

5.  Encryption for Home Users


6.  Security Monitoring for Specific Attack Types

   Effective incident response today requires collaboration at Internet
   scale.  This section will only focus on efforts of collaboration at
   Internet scale that are dedicated to specific attack types.  They may
   require new monitoring and detection techniques in an increasingly
   encrypted Internet.  As mentioned previously, some service providers
   have been interfering with STARTTLS to prevent session encryption to
   be able to perform functions they are used to (injecting ads,
   monitoring, etc.).  By detailing the current monitoring methods used
   for attack detection and response, this information can be used to
   devise new monitoring methods that will be effective in the changed
   Internet via collaboration and innovation.

6.1.  Mail Abuse and SPAM

   The largest operational effort to prevent mail abuse is through the
   Messaging, Malware, Mobile Anti-Abuse Working Group (M3AAWG)[M3AAWG].
   Mail abuse is combated directly with mail administrators who can shut
   down or stop continued mail abuse originating from large scale
   providers that participate in using the Abuse Reporting Format (ARF)

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   agents standardized in the IETF [RFC5965], [RFC6430], [RFC6590],
   [RFC6591], [RFC6650], [RFC6651], and [RFC6652].  The ARF agent
   directly reports abuse messages to the appropriate service provider
   who can take action to stop or mitigate the abuse.  Since this
   technique uses the actual message, the use of TLS over SMTP between
   mail gateways will not effect its usefulness.  As mentioned
   previously, TLS over SMTP only protects data while in transit and the
   messages may be exposed on mail servers or mail gateways if a user-
   to-user encryption method is not used.  Current user-to-user message
   encryption methods on email (S/MIME and PGP) do not encrypt the email
   header information used by ARF and the service provider operators in
   their abuse mitigation efforts.

6.2.  Denial of Service

   Response to Denial of Service (DoS) attacks are typically coordinated
   by the SP community with a few key vendors who have tools to assist
   in the mitigation efforts.  Traffic patterns are determined from each
   DoS attack to stop or rate limit the traffic flows with patterns
   unique to that DoS attack.

   Data types used in monitoring traffic for DDoS are described in Open
   Threat Signaling using RPC API over HTTPS and IPFIX (DDoSMitigation:

   Data types used in DDoS attacks have been detailed in the IODEF
   Guidance draft [I-D.ietf-mile-iodef-guidance], Appendix A.2, with the
   help of several members of the service provider community.  The
   examples provided are intended to help identify the useful data in
   detecting and mitigating these attacks independent of the transport
   and protocol descriptions in the drafts.  [We don't care about a
   format battle for the purpose of this draft, just what is useful for

   [several experts in this area participate in the IETF.  It would be
   good to get an up-to-date picture of this and what information is
   typically helpful in those flows.]

   [If sessions are encrypted, how does that affect the ability of SPs
   and vendors to mitigate or stop the DoS?  ACM: a short description of
   the effect appears in section 2]

6.3.  Phishing

   Investigations and response to phishing attacks follow well-known
   patterns, requiring access to specific fields in email headers as
   well as content from the body of the message.  When reporting
   phishing attacks, the recipient has access to each field as well as

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   the body to make content reporting possible, even when end-to-end
   encryption is used.  The email header information is useful to
   identify the mail servers and accounts used to generate or relay the
   attack messages in order to take the appropriate actions.  The
   content of the message often contains an embedded attack that may be
   in an infected file or may be a link that results in the download of
   malware to the users system.

   Administrators often find it helpful to use header information to
   track down similar message in their mail queue or users inboxes to
   prevent further infection.  Combinations of To:, From:, Subject:,
   Received: from header information might be used for this purpose.
   Administrators may also search for document attachments of the same
   name, size, or containing a file with a matching hash to a known
   phishing attack.  Administrators might also add URLs contained in
   messages to block lists locally or this may also be done by browser
   vendors through larger scales efforts like that of the Anti-Phishing
   Working Group (APWG).

   A full list of the fields used in phishing attack incident response
   can be found in RFC5901.  Future plans to increase privacy
   protections may limit some of these capabilities if some email header
   fields are encrypted, such as To:, From:, and Subject: header fields.
   This does not mean that those fields should not be encrypted, only
   that we should be aware of how they are currently used.  Alternate
   options to detect and prevent phishing attacks may be needed.  More
   recent examples of data exchanged in spear phishing attacks has been
   detailed in the IODEF Guidance draft [I-D.ietf-mile-iodef-guidance],
   Appendix A.3.

6.4.  Botnets

   Botnet detection and mitigation is complex and may involve hundreds
   or thousands of hosts with numerous Command and Control (C&C)
   servers.  The techniques and data used to monitor and detect each may
   vary.  Connections to C&C servers are typically encrypted, therefore
   a move to an increasingly encrypted Internet may not affect the
   detection and sharing methods used.

   [Contributions welcome to detail data used in Botnet detection and
   how that may change in an increasingly encrypted Internet.]

6.5.  eCrime

   [Contributions welcome to better understand data used in tracking
   eCrime and how that may change in an increasingly encrypted

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6.6.  Malware

   Malware monitoring and detection techniques vary.  As mentioned in
   the enterprise section, malware monitoring may occur at gateways to
   the organization analyzing email and web traffic.  These services can
   also be provided by service providers, changing the scale and
   location of this type of monitoring.  Additionally, incident
   responders may identify attributes unique to types of malware to help
   track down instances by their communication patterns on the Internet
   or by alterations to hosts and servers.

   [Contributions welcome to expand this (or any other) section.]  Data
   types used in malware investigations have been summarized in an
   example of the IODEF Guidance draft [I-D.ietf-mile-iodef-guidance],
   Appendix A.1.

6.7.  Blocklists

6.8.  [Any other subsections to be contributed?]

   Although incident response work will continue, new methods to prevent
   system compromise through security automation and continuous
   monitoring [SACM] may provide alternate approaches where system
   security is maintained as a preventative measure.

7.  Response to Increased Encryption and Looking Forward

   As the use of encryption continues to increase, efforts to prevent it
   will continue to emerge.  In the best case scenario, engineers and
   other innovators would work to solve the problems at hand in new ways
   rather than prevent the use of encryption.  It will take time to
   devise alternate approaches to achieve similar goals.

   There has already been documented cases of service providers
   preventing STARTTLS [NoEncrypt] to prevent session encryption
   negotiation on some session to inject a super cookie.  There are
   other service providers who have been injecting Java Script into
   sessions [Net-Neutral], which has obvious security implications as
   well as threatens Net-Neutrality.  The use of session encryption will
   help to prevent possible discrimination to maintain net neutrality,
   but a backlash should be expected.

   National surveillance programs have a clear need for monitoring
   terrorism [CharlieHebdo] as do Internet security practitioners for
   cyber criminal activities.  The UK prime minister, David Cameron,
   emphasized the need for monitoring [UKMonitor] at the expense of user
   privacy and protection of data and assets.  This approach ignores the
   real need to protect users identity, financial transactions and

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   intellectual property, which requires security and encryption to
   prevent cyber crime.  A clear understanding of technology,
   encryption, and monitoring needs will aid in the development of
   solutions to appropriately balance the need of privacy and avoid the
   fears of terrorism.  As this understanding increases, hopefully the
   discussions will improve and this draft is meant to help further the

   Terrorists and cyber criminals have been using encryption for many
   years.  The current push to increase encryption is aimed at
   increasing users privacy.  There is already protection in place for
   purchases, financial transactions, systems management infrastructure,
   and intellectual property although this too can be improved.  The
   Opportunistic Security (OS) [RFC7435] efforts aim to increase the
   costs of monitoring through the use of encryption that can be subject
   to active attacks, but make passive monitoring broadly cost
   prohibitive.  This is meant to restrict monitoring to sessions where
   there is reason to have suspicion.

   As the use of encryption increases, does passive monitoring become
   limited to metadata analysis?  What metadata should be left in
   protocols as they evolve to also protect users privacy?  Can we make
   changes to protocols and message exchanges to alter the current
   monitoring needs at least for operations and security practitioners?

   Options are on the technology horizon that will help to end the
   struggle between the need to monitor by operators, security teams,
   and nations and those seeking to protect users privacy.  The
   solutions are very interesting, but are several years out and include
   homomorphic encrypt, functional encryption, and filterable decryption
   [homomorphic].  This technology will allow for searching and pattern
   matching on encrypted data, but is still several years out.

8.  Operational Monitoring

9.  Security Considerations

   There are no additional security considerations as this is a summary
   and does not include a new protocol or functionality.

10.  IANA Considerations

   This memo makes no requests of IANA.

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11.  Acknowledgements

   Thanks to our early reviewers, Ashutosh Dutta and Brandon Williams,
   for their editorial and content suggestions.

12.  References

12.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2", RFC
              4949, August 2007.

12.2.  Informative References

   [CAIDA]    "CAIDA [http://www.caida.org/data/overview/]", .

   [CALEA]    Pub. L. No. 103-414, 108 Stat. 4279, codified at 47 USC
              1001-1010, "Communications Assistance for Law Enforcement
              Act (CALEA)", .

              "Europe Considers Surveillance Expansion After Deady
              Attacks https://firstlook.org/theintercept/2015/01/20/
              europe-considers-surveillance-expansion/", .

   [EFF]      "Electronic Frontier Foundation https://www.eff.org/", .

              Kampanakis, P., "IODEF Usage Guidance", draft-ietf-mile-
              iodef-guidance-03 (work in progress), May 2014.

              Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
              Known Attacks on TLS and DTLS", draft-ietf-uta-tls-
              attacks-05 (work in progress), October 2014.

              Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of TLS and DTLS", draft-
              ietf-uta-tls-bcp-11 (work in progress), February 2015.

              Teague, N., "Open Threat Signaling using RPC API over
              HTTPS and IPFIX", draft-teague-open-threat-signaling-00
              (work in progress), January 2015.

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   [M3AAWG]   "Messaging, Malware, Mobile Anti-Abuse Working Group
              (M3AAWG) https://www.maawg.org/", .

              "Comcast Wifi serving self-promotional ads via JavaScript
              injection http://arstechnica.com/tech-policy/2014/09/why-
              neutrality/", .

              "ISPs Removing their Customers EMail Encryption
              attacks/", .

   [PANO]     "Panopticlick [https://panopticlick.eff.org/]", .

   [RFC2822]  Resnick, P., "Internet Message Format", RFC 2822, April

   [RFC5965]  Shafranovich, Y., Levine, J., and M. Kucherawy, "An
              Extensible Format for Email Feedback Reports", RFC 5965,
              August 2010.

   [RFC6430]  Li, K. and B. Leiba, "Email Feedback Report Type Value:
              not-spam", RFC 6430, November 2011.

   [RFC6455]  Fette, I. and A. Melnikov, "The WebSocket Protocol", RFC
              6455, December 2011.

   [RFC6590]  Falk, J. and M. Kucherawy, "Redaction of Potentially
              Sensitive Data from Mail Abuse Reports", RFC 6590, April

   [RFC6591]  Fontana, H., "Authentication Failure Reporting Using the
              Abuse Reporting Format", RFC 6591, April 2012.

   [RFC6650]  Falk, J. and M. Kucherawy, "Creation and Use of Email
              Feedback Reports: An Applicability Statement for the Abuse
              Reporting Format (ARF)", RFC 6650, June 2012.

   [RFC6651]  Kucherawy, M., "Extensions to DomainKeys Identified Mail
              (DKIM) for Failure Reporting", RFC 6651, June 2012.

   [RFC6652]  Kitterman, S., "Sender Policy Framework (SPF)
              Authentication Failure Reporting Using the Abuse Reporting
              Format", RFC 6652, June 2012.

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   [RFC7143]  Chadalapaka, M., Satran, J., Meth, K., and D. Black,
              "Internet Small Computer System Interface (iSCSI) Protocol
              (Consolidated)", RFC 7143, April 2014.

   [RFC7146]  Black, D. and P. Koning, "Securing Block Storage Protocols
              over IP: RFC 3723 Requirements Update for IPsec v3", RFC
              7146, April 2014.

   [RFC7258]  Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
              Attack", BCP 188, RFC 7258, May 2014.

   [RFC7435]  Dukhovni, V., "Opportunistic Security: Some Protection
              Most of the Time", RFC 7435, December 2014.

   [TOR]      "TOR ...", .

              "Cameron wants to ban encryption
              banking-messaging-terror", .

              "Securing the Cloud http://newsoffice.mit.edu/2013/
              algorithm-solves-homomorphic-encryption-problem-0610", .

Authors' Addresses

   Kathleen Moriarty
   EMC Corporation
   176 South St
   Hopkinton, MA

   Phone: +1
   Email: Kathleen.Moriarty@emc.com

   Al Morton
   AT&T Labs
   200 Laurel Avenue South
   Middletown,, NJ  07748

   Phone: +1 732 420 1571
   Fax:   +1 732 368 1192
   Email: acmorton@att.com
   URI:   http://home.comcast.net/~acmacm/

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