├── .github └── ISSUE_TEMPLATE │ └── feedback-on-peach-framework.md ├── LICENSE.md ├── README.md ├── assets ├── attack-sequence.png ├── chaosdb.png ├── peaches.png ├── review-process.png └── test ├── case-studies └── chaosdb.md ├── examples └── interface-examples.md └── specifications ├── hardening-factors.md └── security-boundaries.md /.github/ISSUE_TEMPLATE/feedback-on-peach-framework.md: -------------------------------------------------------------------------------- 1 | --- 2 | name: Feedback on PEACH framework 3 | about: Use this to share feedback about PEACH 4 | title: '' 5 | labels: '' 6 | assignees: '' 7 | 8 | --- 9 | 10 | ------- 11 | If Wiz receives any feedback (e.g., questions, comments, suggestions, contributions or the like, whether orally or in writing) regarding this research (collectively, “Feedback”), you hereby grant Wiz a worldwide, sublicensable, transferrable, perpetual, irrevocable, royalty-free license to use, disclose, reproduce, license, or otherwise distribute and exploit the Feedback without obligation or restriction of any kind on account of intellectual property rights or otherwise, and without the obligation to provide any credit. 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2 | 3 | ## PEACH: a tenant isolation framework for cloud applications 4 | 5 | Over the past year and a half, Wiz researchers and other members of the cloud security community discovered several cross-tenant vulnerabilities in various multi-tenant cloud applications (including [ChaosDB](https://www.wiz.io/blog/chaosdb-how-we-hacked-thousands-of-azure-customers-databases), [ExtraReplica](https://www.wiz.io/blog/wiz-research-discovers-extrareplica-cross-account-database-vulnerability-in-azure-postgresql) and [Hell’s Keychain](https://www.wiz.io/blog/hells-keychain-supply-chain-attack-in-ibm-cloud-databases-for-postgresql)). Each of these critical vulnerabilities could have potentially enabled malicious actors to access data belonging to any customer of the affected applications. 6 | 7 |

Typical vulnerability-enabled cross-tenant attack sequence

8 |

Typical vulnerability-enabled cross-tenant attack sequence

9 | 10 | Although these issues have been reported on extensively and were dealt with appropriately by the relevant vendors, we’ve seen little public discussion on how to mitigate such vulnerabilities across the entire industry. The vast majority of modern SaaS and PaaS applications are multi-tenant, and anyone building or using these services should have an interest in solving this problem. 11 | 12 | In addition, something that stood out to us about each of these vulnerabilities was their root cause: **improperly implemented security boundaries**, usually compounded by otherwise harmless **bugs in customer-facing interfaces**. 13 | 14 | As time went by, we began noticing a problematic pattern: 15 | 1. There is no **common language** in the industry to talk about best practices for tenant isolation, so each vendor ends up relying on different terminology and implementation standards for their security boundaries, making it difficult to assess their efficacy. 16 | 2. There is no **baseline** for what measures vendors should be expected to take in order to ensure tenant isolation in their products, neither in terms of which boundaries they’re using or how they are actually implemented. 17 | 3. There is no standard for **transparency** – while some vendors are very forthcoming about the details of their security boundaries, others share very little about them. This makes it harder for customers to manage the risks of using cloud applications. 18 | 19 | This led us to develop **PEACH**, with the goal of modelling tenant isolation in cloud applications, evaluating security posture, and outlining ways to improve it if necessary - all based on the lessons we've learned in our cloud vulnerability research. 20 | 21 | ### Using PEACH 22 | 23 | The first part of the security review process involves a tenant isolation review (see example [here](/case-studies/chaosdb.md)). This isolation review analyzes the risks associated with customer-facing interfaces and determines: 24 | 1. The **complexity of the interface** as a predictor of vulnerability (see examples [here](/examples/interface-examples.md)); 25 | 2. Whether the interface is **shared or duplicated** per tenant; 26 | 3. What type of **security boundaries** are in place (e.g. hardware virtualization - see other types [here](/specifications/security-boundaries.md)); 27 | 4. How strongly these boundaries have been **implemented**. 28 | 29 | In order to gauge how strongly the security boundaries have been implemented (4), we propose using the following five parameters (P.E.A.C.H. - defined in detail [here](/specifications/hardening-factors.md)): 30 | 1. **P**rivilege hardening 31 | 2. **E**ncryption hardening 32 | 3. **A**uthentication hardening 33 | 4. **C**onnectivity hardening 34 | 5. **H**ygiene 35 | 36 | The second part of the security review process consists of remediation steps to manage the risk of cross-tenant vulnerabilities and improve isolation as necessary. These includes reducing interface complexity, enhancing tenant separation, and increasing interface duplication, all while accounting for operational context such as budget constraints, compliance requirements, and expected use-case characteristics of the service. 37 | 38 |

Isolation design review procedure

39 |

Isolation design review procedure

40 | 41 | ### Getting started with PEACH 42 | 43 | To find out more about the PEACH framework, check out the [PEACH website](https://peach.wiz.io) you to learn about principles for designing cloud applications with strong tenant isolation, and modelling your services against the threat of isolation escape. Additionally, you can see which questions to ask vendors to evaluate your security posture considering the risk of cross-tenant vulnerabilities. You may also read [our new whitepaper](https://www.datocms-assets.com/75231/1671033753-peach_whitepaper_ver1-1.pdf), which takes a closer look at the PEACH framework while delving into prior work on the subject of tenant isolation. 44 | 45 | ### Get involved 46 | 47 | We would be thrilled to receive your feedback so we can improve the framework and make it as useful as possible for cloud application developers – feel free to reach out to us directly or [create an issue](https://github.com/wiz-sec/peach-framework/issues/new) here in our GitHub repository. 48 | 49 | You can also contribute to this project by adding content, such as your own [case studies](/case-studies) of using the framework to analyze the isolation scheme of a cloud application or to determine the root cause of a cloud vulnerability. 50 | 51 | ### Acknowledgements 52 | We would like to extend our gratitude to Christophe Parisel (Senior Cloud Security Architect, Société Générale), Cfir Cohen (Staff Software Engineer, Google), Kat Traxler (Principal Security Researcher, VectraAI), Srinath Kuruvadi (Head of Cloud Security, Netflix), Joseph Kjar (Senior Cloud Security Engineer, Netflix), Mike Kuhn (Managing Principal, Coalfire), Daniel Pittner (Software Architect, IBM Cloud), and Adam Callis (Information Security Architect, Cisco) for sharing constructive input throughout the development of this framework. 53 | 54 | We would also like to thank AWS for their review of our whitepaper and the valuable feedback they provided. We highly appreciate their willingness to help us identify tenant isolation best practices and their commitment to improving security transparency for cloud customers. 55 | 56 | [![License: CC BY-NC-SA 4.0](https://img.shields.io/badge/License-CC%20BY--NC--SA%204.0-lightgrey.svg)](https://creativecommons.org/licenses/by-nc-sa/4.0/) 57 | -------------------------------------------------------------------------------- /assets/attack-sequence.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/wiz-sec-public/peach-framework/a6b09b896602c3c49f1842d3b86d5392d01cb2a2/assets/attack-sequence.png -------------------------------------------------------------------------------- /assets/chaosdb.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/wiz-sec-public/peach-framework/a6b09b896602c3c49f1842d3b86d5392d01cb2a2/assets/chaosdb.png -------------------------------------------------------------------------------- /assets/peaches.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/wiz-sec-public/peach-framework/a6b09b896602c3c49f1842d3b86d5392d01cb2a2/assets/peaches.png -------------------------------------------------------------------------------- /assets/review-process.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/wiz-sec-public/peach-framework/a6b09b896602c3c49f1842d3b86d5392d01cb2a2/assets/review-process.png -------------------------------------------------------------------------------- /assets/test: -------------------------------------------------------------------------------- 1 | 2 | -------------------------------------------------------------------------------- /case-studies/chaosdb.md: -------------------------------------------------------------------------------- 1 | ### Case study – ChaosDB 2 | 3 | [ChaosDB](https://www.wiz.io/blog/chaosdb-explained-azures-cosmos-db-vulnerability-walkthrough) was a cross-tenant vulnerability in Azure Cosmos DB disclosed by Wiz in August 2021. The attack sequence consisted of deploying an embedded Jupyter Notebook, exploiting a local privilege escalation vulnerability, modifying firewall rules to gain unrestricted network access, authenticating to the CosmosDB backend, and abusing this access to retrieve and decrypt other tenants’ credentials. 4 | 5 | By using the PEACH framework to model Cosmos DB’s initial state prior to ChaosDB’s disclosure, we can conduct a root cause analysis of the vulnerability. To the best of our understanding, each tenant’s embedded Jupyter Notebook ran in a container nested within a virtual machine. Although this might appear to be a strong isolation scheme, the interface’s hardening factors revealed critical gaps at the implementation level: 6 | 1. **Privilege** hardening gap – tenant-allocated VM with access to shared admin certificate. 7 | 2. **Encryption** hardening gap – tenant API keys encrypted with shared key. 8 | 3. **Authentication** hardening gap – self-signed certificate not validated. 9 | 4. **Connectivity** hardening gap – network controls only enforced within container (iptables) and orchestrator interface accessible from tenant container. 10 | 5. **Hygiene** gap – tenant access to unrelated certificates and keys. 11 | 12 |

Estimated isolation scheme of Cosmos DB-embedded Jupyter Notebook at the time of ChaosDB’s discovery

13 |

Estimated isolation scheme of Cosmos DB-embedded Jupyter Notebook at the time of ChaosDB’s discovery

14 | 15 | While this isolation scheme can ensure tenant isolation for relatively simple interfaces, it is ill-suited to highly complex ones such as Jupyter Notebook. In the case of ChaosDB, this complexity resulted in PEACH gaps that ultimately enabled our attack sequence to unfold. 16 | -------------------------------------------------------------------------------- /examples/interface-examples.md: -------------------------------------------------------------------------------- 1 | | **Interface type** | **Typical input (example)** | **Typical process** | **Complexity level** 2 | |--|--|--|--| 3 | | Arbitrary code execution environment | Arbitrary | Execution | High | 4 | | Database client | SQL query | Database operation | High | 5 | | Arbitrary file scanner | Arbitrary | Parsing | Medium | 6 | | Binary data parsing | Protobuf | Parsing | Medium | 7 | | Web crawler | JavaScript | Rendering | Medium | 8 | | Port scanner | Metadata | Parsing | Low | 9 | | Reverse proxy | Arbitrary | Proxy | Low | 10 | | Queue message upload | Arbitrary | Proxy | Low | 11 | | Data entry form | String | Parsing | Low | 12 | | Bucket file upload | Arbitrary | Storage | Low | 13 | -------------------------------------------------------------------------------- /specifications/hardening-factors.md: -------------------------------------------------------------------------------- 1 | ## Privilege Hardening 2 | 1. Tenants and hosts generally have minimal permissions in the service environment, thereby adhering to the principle of least privilege. 3 | 2. In particular, each tenant is not authorized to read or write to other tenants’ data unless explicitly approved by the tenants involved, and each host does not have read or write access to other hosts. 4 | 3. Privileges are verified prior to execution of operations. 5 | 6 | ## Encryption Hardening 7 | 1. Data owned by and related to each tenant – at-rest and in-transit – is encrypted with a key unique to that tenant, regardless of architecture. 8 | 2. Logs pertaining to each tenant’s activity are encrypted by a secret shared only between the tenant and the control plane . 9 | 10 | ## Authentication Hardening 11 | 1. Communications between each tenant and the control plane (in both directions) use authentication with a key or certificate unique to each tenant. 12 | 2. Authentication keys are validated, and self-signed keys are blocked. 13 | 14 | ## Connectivity Hardening 15 | 1. All inter-host connectivity is blocked by default unless explicitly approved by the tenants involved (so as to facilitate database replication, for example); hosts cannot connect to other hosts in the service environment, except those used by the control plane (i.e., a hub-and-spoke configuration). 16 | 2. Hosts do not accept incoming connection requests from other hosts unless explicitly approved by the tenants involved, except those used by the control plane (in anticipation of scenarios in which an attacker manages to overcome connectivity limitations on their own compromised host). 17 | 3. Tenants cannot arbitrarily access any external resource (both within the service environment and on the Internet) and are limited to communicating with only pre-approved resources or those explicitly approved by the tenant. 18 | 19 | ## Hygiene 20 | Unnecessary data scattered throughout the environment might serve as clues or quick wins for malicious actors, particularly those that have managed to breach one or more security boundaries, which in turn enable further reconnaissance and lateral movement. Therefore, vendors can eliminate the following types of data at the design level and also regularly scan for forgotten artifacts: 21 | 1. Secrets – The interface and datastore (and underlying host, in the case of virtualization or containerization) do not contain any keys or credentials that would allow authentication to other tenants’ environments or decryption of other tenants’ backend communications or logs. 22 | 2. Software – The instance and datastore (and underlying host) do not contain any built-in software or source code that could enable reconnaissance or lateral movement. 23 | 3. Logs – Each tenant’s logs are hidden from and inaccessible by other tenants; logs accessible to each tenant do not contain any information pertaining to other tenants’ activity. 24 | -------------------------------------------------------------------------------- /specifications/security-boundaries.md: -------------------------------------------------------------------------------- 1 | # Primary Boundaries 2 | 3 | ## Hardware Separation 4 | Wherein instances belonging to different tenants run on separate physical machines (IaaS such as bare-metal servers or dedicated physical datacenters). This is the highest practical level of isolation but is not considered cost-effective at scale, nor is the added level of isolation significant in comparison to the use of industry-vetted hardware virtualization (this becomes especially apparent in cases where hardware separation has been insufficiently hardened). 5 | 6 | ## Hardware Virtualization 7 | Wherein instances belonging to different tenants run in separate virtual machines running on shared hardware. This is generally considered a high level of isolation. 8 | 9 | ## Containerization 10 | Wherein instances belonging to different tenants run in separate containers running on shared hardware (or nested within a shared virtual machine) via operating-system-level virtualization. Containers are not considered an especially effective security boundary on their own, and therefore this should generally be treated as a low level of isolation. 11 | 12 | When using containerization as a security boundary, vendors should enforce permission restrictions on deployed workloads , via technologies such as SECCOMP , AppArmor and gVisor , thereby limiting the capacity of a compromised container from affecting its host. Additional mitigations may include implementing a read-only filesystem, limiting the privileges of user accounts, disabling the root user, and minimizing the number of running highly privileged processes. Moreover, vendors should generally prefer the use of hardened operating systems. 13 | 14 | ## Data Segmentation 15 | Wherein data belonging to different tenants is stored and/or processed on a shared storage component (virtual or physical), but unique keys are used to encrypt and/or authorize access to each tenant’s data. This is generally considered a low level of isolation, as it’s highly dependent on the implementation of other aspects of the architecture (such as key storage security). 16 | 17 | # Secondary Boundaries 18 | 19 | ## Network Segmentation 20 | Wherein instances belonging to different tenants run on separate machines (virtual or physical) in the same network, which is segmented into single tenant VPNs or subnets (logically separated via encapsulation, encryption, and firewalling). This is generally considered a high level of isolation. 21 | 22 | ## Identity Segmentation 23 | Wherein roles are assigned to different tenants (whether or not customers can access them directly under normal circumstances) which are limited by deny-by-default policies, such that each tenant cannot perform any actions affecting resources belonging to any other tenant . This is generally considered a high level of isolation. 24 | --------------------------------------------------------------------------------