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首页"Google网络安全白皮书-20181: 云负载平衡器的安全解决方案"
"Google网络安全白皮书-20181: 云负载平衡器的安全解决方案"
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更新于2024-01-11
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Google网络安全白皮书-20181提供了关于Google网络安全的详细信息,包括服务器负载平衡、DoS攻击防护、终端用户认证、身份验证和授权等方面的内容。其中,Cloud Load Balancer服务是建立在GFE之上的,可以应对许多类型的DoS攻击。同时,终端用户对GCE控制平面API的身份验证是通过Google的集中身份管理服务完成的,该服务提供了诸如劫持检测等安全功能。授权则是通过集中的云IAM服务进行的。控制平面的网络流量,包括从GFE到其后的第一个服务以及其他控制平面服务之间的流量,均会自动通过身份验证。
在Google网络安全白皮书-20181中指出,Cloud Load Balancer服务是建立在GFE之上的,不仅可以优化网络流量,还可以减缓和抵御各种类型的DoS攻击。这意味着,用户可以更加放心地使用Google的网络服务,不必过多担心遭受网络攻击的威胁。
另外,白皮书还介绍了关于终端用户认证和授权的一些内容。终端用户对GCE控制平面API的身份验证是通过Google的集中身份管理服务进行的,这个服务还提供了劫持检测等安全功能。同时,授权是通过集中的云IAM服务进行的,这意味着用户可以在集中管理的平台上轻松地对用户进行授权管理,从而加强了整个系统的安全性。
另外,白皮书还详细介绍了控制平面的网络流量安全方面的内容。它指出,控制平面的网络流量,包括从GFE到其后的第一个服务以及其他控制平面服务之间的流量,均会自动通过身份验证。这意味着在控制平面上,网络流量不会受到未经授权的访问,从而保障了整个系统的网络安全。
综上所述,Google网络安全白皮书-20181提供了关于Google网络安全的详尽信息,内容涵盖了服务器负载平衡、DoS攻击防护、终端用户认证、身份验证和授权、网络流量安全等方面。用户可以通过阅读这份白皮书,深入了解Google的网络安全防护措施,从而更加放心地使用Google的网络服务。
![](https://csdnimg.cn/release/download_crawler_static/86301993/bg4.jpg)
Cloud Load Balancer service which is built on top of the GFE and can mitigate
many types of DoS attacks.
End user authentication to the GCE control plane API is done via Google’s
centralized identity service which provides security features such as hijacking
detection. Authorization is done using the central Cloud IAM service.
The network traffic for the control plane, both from the GFEs to the first service
behind it and between other control plane services is automatically
authenticated by the infrastructure and encrypted whenever it travels from one
data center to another. Additionally, the infrastructure has been configured to
encrypt some of the control plane traffic within the data center as well.
Each virtual machine (VM) runs with an associated virtual machine manager
(VMM) service instance. The infrastructure provides these services with two
identities. One identity is used by the VMM service instance for its own calls and
one identity is used for calls that the VMM makes on behalf of the customer’s
VM. This allows us to further segment the trust placed in calls coming from
the VMM.
GCE persistent disks are encrypted at-rest using keys protected by the central
infrastructure key management system. This allows for automated rotation and
central auditing of access to these keys.
Customers today have the choice of whether to send traffic from their VMs to
other VMs or the internet in the clear, or to implement any encryption they
choose for this traffic. We have started rolling out automatic encryption for the
WAN traversal hop of customer VM to VM traffic. As described earlier, all control
plane WAN traffic within the infrastructure is already encrypted. In the future we
plan to take advantage of the hardware-accelerated network encryption
discussed earlier to also encrypt inter-VM LAN traffic within the data center.
The isolation provided to the VMs is based on hardware virtualization using the
open source KVM stack. We have further hardened our particular
implementation of KVM by moving some of the control and hardware emulation
stack into an unprivileged process outside the kernel. We have also extensively
tested the core of KVM using techniques like fuzzing, static analysis, and manual
code review. As mentioned earlier, the majority of the recently publicly disclosed
vulnerabilities which have been upstreamed into KVM came from Google.
Finally, our operational security controls are a key part of making sure that
accesses to data follow our policies. As part of the Google Cloud Platform, GCE’s
use of customer data follows the GCP use of customer data policy, namely that
Google will not access or use customer data, except as necessary to provide
services to customers.
diagnose hardware and software problems, and to remove machines from
service if necessary.
Secure Service Deployment
We will now go on to describe how we go from the base hardware and software
to ensuring that a service is deployed securely on our infrastructure. By ‘service’
we mean an application binary that a developer wrote and wants to run on our
infrastructure, for example, a Gmail SMTP server, a BigTable storage server, a
YouTube video transcoder, or an App Engine sandbox running a customer
application. There may be thousands of machines running copies of the same
service to handle the required scale of the workload. Services running on the
infrastructure are controlled by a cluster orchestration service called Borg.
As we will see in this section, the infrastructure does not assume any trust
between services running on the infrastructure. In other words, the infrastructure
is fundamentally designed to be multi-tenant.
Service Identity, Integrity, and Isolation
We use cryptographic authentication and authorization at the application layer
for inter-service communication. This provides strong access control at an
abstraction level and granularity that administrators and services can
naturally understand.
We do not rely on internal network segmentation or firewalling as our primary
security mechanisms, though we do use ingress and egress filtering at various
points in our network to prevent IP spoofing as a further security layer. This
approach also helps us to maximize our network’s performance and availability.
Each service that runs on the infrastructure has an associated service account
identity. A service is provided cryptographic credentials that it can use to prove
its identity when making or receiving remote procedure calls (RPCs) to other
services. These identities are used by clients to ensure that they are talking to
the correct intended server, and by servers to limit access to methods and data
to particular clients.
Google’s source code is stored in a central repository where both current and
past versions of the service are auditable. The infrastructure can additionally be
configured to require that a service’s binaries be built from specific reviewed,
checked in, and tested source code. Such code reviews require inspection and
approval from at least one engineer other than the author, and the system
enforces that code modifications to any system must be approved by the
owners of that system. These requirements limit the ability of an insider or
adversary to make malicious modifications to source code and also provide a
forensic trail from a service back to its source.
After our backbone delivers an external connection to one of our data centers, it
passes through several layers of hardware and software load-balancing. These
load balancers report information about incoming traffic to a central DoS service
running on the infrastructure. When the central DoS service detects that a DoS
attack is taking place, it can configure the load balancers to drop or throttle
traffic associated with the attack.
At the next layer, the GFE instances also report information about requests that
they are receiving to the central DoS service, including application layer
information that the load balancers don’t have. The central DoS service can then
also configure the GFE instances to drop or throttle attack traffic.
User Authentication
After DoS protection, the next layer of defense comes from our central identity
service. This service usually manifests to end users as the Google login page.
Beyond asking for a simple username and password, the service also
intelligently challenges users for additional information based on risk factors
such as whether they have logged in from the same device or a similar location
in the past. After authenticating the user, the identity service issues credentials
such as cookies and OAuth tokens that can be used for subsequent calls.
Users also have the option of employing second factors such as OTPs or
phishing-resistant Security Keys when signing in. To ensure that the benefits go
beyond Google, we have worked in the FIDO Alliance with multiple device
vendors to develop the Universal 2nd Factor (U2F) open standard. These devices
are now available in the market and other major web services also have followed
us in implementing U2F support.
Operational Security
Up to this point we have described how security is designed into our
infrastructure and have also described some of the mechanisms for secure
operation such as access controls on RPCs.
We now turn to describing how we actually operate the infrastructure securely:
We create infrastructure software securely, we protect our employees’ machines
and credentials, and we defend against threats to the infrastructure from both
insiders and external actors.
Safe Software Development
Beyond the central source control and two-party review features described
earlier, we also provide libraries that prevent developers from introducing certain
classes of security bugs. For example, we have libraries and frameworks that
eliminate XSS vulnerabilities in web apps. We also have automated tools for
automatically detecting security bugs including fuzzers, static analysis tools, and
web security scanners.
Introduction
This document gives an overview of how security is designed into Google’s
technical infrastructure. This global scale infrastructure is designed to provide
security through the entire information processing lifecycle at Google. This
infrastructure provides secure deployment of services, secure storage of data
with end user privacy safeguards, secure communications between services,
secure and private communication with customers over the internet, and safe
operation by administrators.
Google uses this infrastructure to build its internet services, including both
consumer services such as Search, Gmail, and Photos, and enterprise services
such as G Suite and Google Cloud Platform.
We will describe the security of this infrastructure in progressive layers starting
from the physical security of our data centers, continuing on to how the hardware
and software that underlie the infrastructure are secured, and finally, describing
the technical constraints and processes in place to support operational security.
Services can configure the level of cryptographic protection they want for each
infrastructure RPC (e.g. only configure integrity-level protection for low value
data inside data centers). To protect against sophisticated adversaries who may
be trying to tap our private WAN links, the infrastructure automatically encrypts
all infrastructure RPC traffic which goes over the WAN between data centers,
without requiring any explicit configuration from the service. We have started to
deploy hardware cryptographic accelerators that will allow us to extend this
default encryption to all infrastructure RPC traffic inside our data centers.
Access Management of End User Data
A typical Google service is written to do something for an end user. For example,
an end user may store their email on Gmail. The end user’s interaction with an
application like Gmail spans other services within the infrastructure. So for
example, the Gmail service may call an API provided by the Contacts service to
access the end user’s address book.
We have seen in the preceding section that the Contacts service can be
configured such that the only RPC requests that are allowed are from the Gmail
service (or from any other particular services that the Contacts service wants
to allow).
This, however, is still a very broad set of permissions. Within the scope of this
permission the Gmail service would be able to request the contacts of any user
at any time.
Since the Gmail service makes an RPC request to the Contacts service on behalf
of a particular end user, the infrastructure provides a capability for the Gmail
service to present an “end user permission ticket” as part of the RPC. This ticket
proves that the Gmail service is currently servicing a request on behalf of that
particular end user. This enables the Contacts service to implement a safeguard
where it only returns data for the end user named in the ticket.
The infrastructure provides a central user identity service which issues these
“end user permission tickets”. An end user login is verified by the central identity
service which then issues a user credential, such as a cookie or OAuth token, to
the user’s client device. Every subsequent request from the client device into
Google needs to present that user credential.
When a service receives an end user credential, it passes the credential to the
central identity service for verification. If the end user credential verifies correctly,
the central identity service returns a short-lived “end user permission ticket” that
can be used for RPCs related to the request. In our example, that service which
gets the “end user permission ticket” would be the Gmail service, which would
pass it to the Contacts service. From that point on, for any cascading calls, the
“end user permission ticket” can be handed down by the calling service to the
callee as a part of the RPC call.
We have a variety of isolation and sandboxing techniques for protecting a
service from other services running on the same machine. These techniques
include normal Linux user separation, language and kernel-based sandboxes,
and hardware virtualization. In general, we use more layers of isolation for riskier
workloads; for example, when running complex file format converters on
user-supplied data or when running user supplied code for products like Google
App Engine or Google Compute Engine. As an extra security boundary, we enable
very sensitive services, such as the cluster orchestration service and some key
management services, to run exclusively on dedicated machines.
Inter-Service Access Management
The owner of a service can use access management features provided by the
infrastructure to specify exactly which other services can communicate with it.
For example, a service may want to offer some APIs solely to a specific whitelist
of other services. That service can be configured with the whitelist of the
allowed service account identities and this access restriction is then
automatically enforced by the infrastructure.
Google engineers accessing services are also issued individual identities, so
services can be similarly configured to allow or deny their accesses. All of these
types of identities (machine, service, and employee) are in a global name space
that the infrastructure maintains. As will be explained later in this document, end
user identities are handled separately.
The infrastructure provides a rich identity management workflow system for
these internal identities including approval chains, logging, and notification. For
example, these identities can be assigned to access control groups via a system
that allows two party-control where one engineer can propose a change to a
group that another engineer (who is also an administrator of the group) must
approve. This system allows secure access management processes to scale to
the thousands of services running on the infrastructure.
In addition to the automatic API-level access control mechanism, the
infrastructure also provides services the ability to read from central ACL and
group databases so that they can implement their own custom, fine-grained
access control where necessary.
Encryption of Inter-Service Communication
Beyond the RPC authentication and authorization capabilities discussed in the
previous sections, the infrastructure also provides cryptographic privacy and
integrity for RPC data on the network. To provide these security benefits to other
application layer protocols such as HTTP, we encapsulate them inside our
infrastructure RPC mechanisms. In essence, this gives application layer isolation
and removes any dependency on the security of the network path. Encrypted
inter-service communication can remain secure even if the network is tapped or
a network device is compromised.
Conclusion
We have described how the Google infrastructure is designed to build, deploy
and operate services securely at internet scale. This includes both consumer
services such as Gmail and our enterprise services. In addition, our Google
Cloud offerings are built on top of this same infrastructure.
We invest heavily in securing our infrastructure. We have many hundreds of
engineers dedicated to security and privacy distributed across all of Google,
including many who are recognized industry authorities.
As we have seen, the security in the infrastructure is designed in layers starting
from the physical components and data center, to hardware provenance, and
then on to secure boot, secure inter-service communication, secured data at
rest, protected access to services from the internet and finally, the technologies
and people processes we deploy for operational security.
Additional Reading
Please see the following papers for more detail on specific areas:
1. Physical security of our data centers
https://goo.gl/WYlKGG
2. Design of our cluster management and orchestration
http://research.google.com/pubs/pub43438.html
3. Storage encryption and our customer facing GCP encryption features
https://cloud.google.com/security/encryption-at-rest/
4. BigTable storage service
http://research.google.com/archive/bigtable.html
5. Spanner storage service
http://research.google.com/archive/spanner.html
6. Architecture of our network load balancing
http://research.google.com/pubs/pub44824.html
7. BeyondCorp approach to enterprise security
http://research.google.com/pubs/pub43231.html
Deletion of Data
Deletion of data at Google most often starts with marking specific data as
“scheduled for deletion” rather than actually removing the data entirely. This
allows us to recover from unintentional deletions, whether customer-initiated or
due to a bug or process error internally. After having been marked as “scheduled
for deletion,” the data is deleted in accordance with service-specific policies.
When an end user deletes their entire account, the infrastructure notifies
services handling end user data that the account has been deleted. The
services can then schedule data associated with the deleted end user account
for deletion.
Secure Internet Communication
Until this point in this document, we have described how we secure services on
our infrastructure. In this section we turn to describing how we secure
communication between the internet and these services.
As discussed earlier, the infrastructure consists of a large set of physical
machines which are interconnected over the LAN and WAN and the security of
inter-service communication is not dependent on the security of the network.
However, we do isolate our infrastructure from the internet into a private IP
space so that we can more easily implement additional protections such as
defenses against denial of service (DoS) attacks by only exposing a subset of
the machines directly to external internet traffic.
Google Front End Service
When a service wants to make itself available on the Internet, it can register itself
with an infrastructure service called the Google Front End (GFE). The GFE
ensures that all TLS connections are terminated using correct certificates and
following best practices such as supporting perfect forward secrecy. The GFE
additionally applies protections against Denial of Service attacks (which we will
discuss in more detail later). The GFE then forwards requests for the service
using the RPC security protocol discussed previously.
In effect, any internal service which chooses to publish itself externally uses the
GFE as a smart reverse-proxy front end. This front end provides public IP hosting
of its public DNS name, Denial of Service (DoS) protection, and TLS termination.
Note that GFEs run on the infrastructure like any other service and thus have the
ability to scale to match incoming request volumes.
Denial of Service (DoS) Protection
The sheer scale of our infrastructure enables Google to simply absorb many DoS
attacks. That said, we have multi-tier, multi-layer DoS protections that further
reduce the risk of any DoS impact on a service running behind a GFE.
As a final check, we use manual security reviews that range from quick triages
for less risky features to in-depth design and implementation reviews for the
most risky features. These reviews are conducted by a team that includes
experts across web security, cryptography, and operating system security. The
reviews can also result in new security library features and new fuzzers that can
then be applied to other future products.
In addition, we run a Vulnerability Rewards Program where we pay anyone who
is able to discover and inform us of bugs in our infrastructure or applications.
We have paid several million dollars in rewards in this program.
Google also invests a large amount of effort in finding 0-day exploits and other
security issues in all the open source software we use and upstreaming these
issues. For example, the OpenSSL Heartbleed bug was found at Google and
we are the largest submitter of CVEs and security bug fixes for the Linux
KVM hypervisor.
Keeping Employee Devices and Credentials Safe
We make a heavy investment in protecting our employees’ devices and
credentials from compromise and also in monitoring activity to discover
potential compromises or illicit insider activity. This is a critical part of our
investment in ensuring that our infrastructure is operated safely.
Sophisticated phishing has been a persistent way to target our employees. To
guard against this threat we have replaced phishable OTP second factors with
mandatory use of U2F-compatible Security Keys for our employee accounts.
We make a large investment in monitoring the client devices that our employees
use to operate our infrastructure. We ensure that the operating system images
for these client devices are up-to-date with security patches and we control the
applications that can be installed. We additionally have systems for scanning
user-installed apps, downloads, browser extensions, and content browsed from
the web for suitability on corp clients.
Being on the corporate LAN is not our primary mechanism for granting access
privileges. We instead use application-level access management controls which
allow us to expose internal applications to only specific users when they are
coming from a correctly managed device and from expected networks and
geographic locations. (For more detail see our additional reading about
‘BeyondCorp’.)
Reducing Insider Risk
We aggressively limit and actively monitor the activities of employees who have
been granted administrative access to the infrastructure and continually work to
eliminate the need for privileged access for particular tasks by providing
automation that can accomplish the same tasks in a safe and controlled way.
This includes requiring two-party approvals for some actions and introducing
limited APIs that allow debugging without exposing sensitive information.
Google employee access to end user information can be logged through
low-level infrastructure hooks. Google’s security team actively monitors access
patterns and investigates unusual events.
Intrusion Detection
Google has sophisticated data processing pipelines which integrate host-based
signals on individual devices, network-based signals from various monitoring
points in the infrastructure, and signals from infrastructure services. Rules and
machine intelligence built on top of these pipelines give operational security
engineers warnings of possible incidents. Our investigation and incident
response teams triage, investigate, and respond to these potential incidents 24
hours a day, 365 days a year. We conduct Red Team exercises to measure and
improve the effectiveness of our detection and response mechanisms.
Securing the Google Cloud
Platform (GCP)
In this section, we highlight how our public cloud infrastructure, GCP, benefits
from the security of the underlying infrastructure. In this section, we will take
Google Compute Engine (GCE) as an example service and describe in detail the
service-specific security improvements that we build on top of the infrastructure.
GCE enables customers to run their own virtual machines on Google’s
infrastructure. The GCE implementation consists of several logical components,
most notably the management control plane and the virtual machines
themselves.
The management control plane exposes the external API surface and
orchestrates tasks like virtual machine creation and migration. It runs as a
variety of services on the infrastructure, thus it automatically gets foundational
integrity features such as a secure boot chain. The individual services run under
distinct internal service accounts so that every service can be granted only the
permissions it requires when making remote procedure calls (RPCs) to the rest
of the control plane. As discussed earlier, the code for all of these services is
stored in the central Google source code repository, and there is an audit trail
between this code and the binaries that are eventually deployed.
The GCE control plane exposes its API via the GFE, and so it takes advantage of
infrastructure security features like Denial of Service (DoS) protection and
centrally managed SSL/TLS support. Customers can get similar protections for
applications running on their GCE VMs by choosing to use the optional Google
Secure Data Storage
Up to this point in the discussion, we have described how we deploy services
securely. We now turn to discussing how we implement secure data storage on
the infrastructure.
Encryption at Rest
Google’s infrastructure provides a variety of storage services, such as BigTable
and Spanner, and a central key management service. Most applications at
Google access physical storage indirectly via these storage services. The storage
services can be configured to use keys from the central key management service
to encrypt data before it is written to physical storage. This key management
service supports automatic key rotation, provides extensive audit logs, and
integrates with the previously mentioned end user permission tickets to link keys
to particular end users.
Performing encryption at the application layer allows the infrastructure to isolate
itself from potential threats at the lower levels of storage such as malicious disk
firmware. That said, the infrastructure also implements additional layers of
protection. We enable hardware encryption support in our hard drives and SSDs
and meticulously track each drive through its lifecycle. Before a decommissioned
encrypted storage device can physically leave our custody, it is cleaned using a
multi-step process that includes two independent verifications. Devices that do
not pass this wiping procedure are physically destroyed (e.g. shredded)
on-premise.
2
Secure Low Level Infrastructure
In this section we describe how we secure the lowest layers of our
infrastructure, ranging from the physical premises to the purpose-built hardware
in our data centers to the low-level software stack running on every machine.
Security of Physical Premises
Google designs and builds its own data centers, which incorporate multiple
layers of physical security protections. Access to these data centers is limited to
only a very small fraction of Google employees. We use multiple physical
security layers to protect our data center floors and use technologies like
biometric identification, metal detection, cameras, vehicle barriers, and
laser-based intrusion detection systems. Google additionally hosts some servers
in third-party data centers, where we ensure that there are Google-controlled
physical security measures on top of the security layers provided by the data
center operator. For example, in such sites we may operate independent
biometric identification systems, cameras, and metal detectors.
Hardware Design and Provenance
A Google data center consists of thousands of server machines connected to a
local network. Both the server boards and the networking equipment are
custom-designed by Google. We vet component vendors we work with and
choose components with care, while working with vendors to audit and validate
the security properties provided by the components. We also design custom
chips, including a hardware security chip that is currently being deployed on both
servers and peripherals. These chips allow us to securely identify and
authenticate legitimate Google devices at the hardware level.
Secure Boot Stack and Machine Identity
Google server machines use a variety of technologies to ensure that they are
booting the correct software stack. We use cryptographic signatures over
low-level components like the BIOS, bootloader, kernel, and base operating
system image. These signatures can be validated during each boot or update.
The components are all Google-controlled, built, and hardened. With each new
generation of hardware we strive to continually improve security: for example,
depending on the generation of server design, we root the trust of the boot chain
in either a lockable firmware chip, a microcontroller running Google-written
security code, or the above mentioned Google-designed security chip.
Each server machine in the data center has its own specific identity that can be
tied to the hardware root of trust and the software with which the machine
booted. This identity is used to authenticate API calls to and from low-level
management services on the machine.
Google has authored automated systems to ensure servers run up-to-date
versions of their software stacks (including security patches), to detect and
Figure 1.
Google Infrastructure
Security Layers:
The various layers of security
starting from hardware
infrastructure at the bottom
layer up to operational security
at the top layer. The contents
of each layer are described in
detail in the paper.
Google Infrastructure Security Layers
Intrusion Detection Reducing Insider Risk Safe Employee
Devices & Credentials
Safe Software
Development
Access Management
of End User Data
Encryption of Inter-
Service Communication
Authentication Login Abuse Protection
Google Front End DoS Protection
Encryption at rest Deletion of Data
Inter-Service Access
Management
Service Identity,
Integrity, Isolation
Secure Boot Stack and
Machine Identity
Hardware Design and
Provenance
Security of Physical
Premises
Operational Security
Internet Communication
Storage Services
User Identity
Service Deployment
Hardware Infrastructure
8. Combating phishing with Security Key & the Universal 2nd Factor
(U2F) standard
http://research.google.com/pubs/pub45409.html
9. More about the Google Vulnerability Rewards Program
https://bughunter.withgoogle.com/
10. More about HTTPs and other load balancing offerings on GCP
https://cloud.google.com/compute/docs/load-balancing/
11. More about DoS protection best practices on GCP
https://cloud.google.com/files/GCPDDoSprotection-04122016.pdf
12. Google Cloud Platform use of customer data policy
https://cloud.google.com/terms/
13. More about application security & compliance in G Suite
(Gmail, Drive, etc)
https://goo.gl/3J20R2
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