CVE-2023-51663

Hail is an open-source, general-purpose, Python-based data analysis tool with additional data types and methods for working with genomic data. Hail relies on OpenID Connect (OIDC) email addresses from ID tokens to verify the validity of a user's domain, but because users have the ability to change their email address, they could create accounts and use resources in clusters that they should not have access to. For example, a user could create a Microsoft or Google account and then change their email to [email protected]. This account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is example.org. The attacker is not able to access private data or impersonate another user, but they would have the ability to run jobs if Hail Batch billing projects are enabled and create Azure Tenants if they have Azure Active Directory Administrator access.

Hail is an open-source, general-purpose, Python-based data analysis tool with additional data types and methods for working with genomic data. Hail relies on OpenID Connect (OIDC) email addresses from ID tokens to verify the validity of a user's domain, but because users have the ability to change their email address, they could create accounts and use resources in clusters that they should not have access to. For example, a user could create a Microsoft or Google account and then change their email to [email protected]. This account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is example.org. The attacker is not able to access private data or impersonate another user, but they would have the ability to run jobs if Hail Batch billing projects are enabled and create Azure Tenants if they have Azure Active Directory Administrator access.

Impact

All Hail Batch clusters are affected. An attacker is able to:

1. Create one or more accounts with Hail Batch without corresponding real accounts in the organization.

For example, a user could create a Microsoft or Google account and then change their email to "[email protected]". This Microsoft or Google account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is "example.org".

In Google, this attack is partially mitigated because Google requires users to verify ownership of their Google account. However, a valid user is able to create multiple distinct Hail Batch accounts by creating multiple distinct Google accounts using email addresses of the form "real_[email protected]".

In Microsoft, this attack requires Azure AD Administrator access to an Azure AD Tenant. The Azure AD Administrator is permitted to change the email address of an account to any other email address without verification. An attacker can create an Azure Tenant for free.

1. The attacker does not have access to any private data (because the new service principals or service accounts are not granted any privileges).
2. If trial Hail Batch billing projects are enabled, the attacker does have the ability to run jobs and thus spend money. An attacker can create as many accounts as Microsoft or Google permit.
3. The attacker cannot impersonate another user because, in Azure, we use the sub from the OAuth2 response, and, in Google, Google does an email verification.

Remediation

1. Apply this patch to prevent third-party attackers from creating accounts.
2. Audit your users list https://auth.example.org/users for user accounts whose login ids are not valid login ids with your identity provider. Delete such users.

A forthcoming change will prevent users from creating multiple accounts using Google's + email redirection.

Workarounds

None.

References

1. https://trufflesecurity.com/blog/google-oauth-is-broken-sort-of/
2. https://www.descope.com/blog/post/noauth
3. https://developers.google.com/identity/openid-connect/openid-connect#an-id-tokens-payload
4. https://learn.microsoft.com/en-us/entra/identity-platform/access-token-claims-reference#payload-claims

[1] Hail Batch must separately stop using emails and start using the OAuth2 sub in Google. This is a known deficiency. In particular, if an email is re-used by the organization for a new user, the new user could access the old user's Hail Batch account.

Hail is an open-source, general-purpose, Python-based data analysis tool with additional data types and methods for working with genomic data. Hail relies on OpenID Connect (OIDC) email addresses from ID tokens to verify the validity of a user's domain, but because users have the ability to change their email address, they could create accounts and use resources in clusters that they should not have access to. For example, a user could create a Microsoft or Google account and then change their email to [email protected]. This account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is example.org. The attacker is not able to access private data or impersonate another user, but they would have the ability to run jobs if Hail Batch billing projects are enabled and create Azure Tenants if they have Azure Active Directory Administrator access.

Hail is an open-source, general-purpose, Python-based data analysis tool with additional data types and methods for working with genomic data. Hail relies on OpenID Connect (OIDC) email addresses from ID tokens to verify the validity of a user's domain, but because users have the ability to change their email address, they could create accounts and use resources in clusters that they should not have access to. For example, a user could create a Microsoft or Google account and then change their email to [email protected]. This account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is example.org. The attacker is not able to access private data or impersonate another user, but they would have the ability to run jobs if Hail Batch billing projects are enabled and create Azure Tenants if they have Azure Active Directory Administrator access.

Impact

All Hail Batch clusters are affected. An attacker is able to:

1. Create one or more accounts with Hail Batch without corresponding real accounts in the organization.

For example, a user could create a Microsoft or Google account and then change their email to "[email protected]". This Microsoft or Google account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is "example.org".

In Google, this attack is partially mitigated because Google requires users to verify ownership of their Google account. However, a valid user is able to create multiple distinct Hail Batch accounts by creating multiple distinct Google accounts using email addresses of the form "real_[email protected]".

In Microsoft, this attack requires Azure AD Administrator access to an Azure AD Tenant. The Azure AD Administrator is permitted to change the email address of an account to any other email address without verification. An attacker can create an Azure Tenant for free.

1. The attacker does not have access to any private data (because the new service principals or service accounts are not granted any privileges).
2. If trial Hail Batch billing projects are enabled, the attacker does have the ability to run jobs and thus spend money. An attacker can create as many accounts as Microsoft or Google permit.
3. The attacker cannot impersonate another user because, in Azure, we use the sub from the OAuth2 response, and, in Google, Google does an email verification.

Remediation

1. Apply this patch to prevent third-party attackers from creating accounts.
2. Audit your users list https://auth.example.org/users for user accounts whose login ids are not valid login ids with your identity provider. Delete such users.

A forthcoming change will prevent users from creating multiple accounts using Google's + email redirection.

Workarounds

None.

References

1. https://trufflesecurity.com/blog/google-oauth-is-broken-sort-of/
2. https://www.descope.com/blog/post/noauth
3. https://developers.google.com/identity/openid-connect/openid-connect#an-id-tokens-payload
4. https://learn.microsoft.com/en-us/entra/identity-platform/access-token-claims-reference#payload-claims

[1] Hail Batch must separately stop using emails and start using the OAuth2 sub in Google. This is a known deficiency. In particular, if an email is re-used by the organization for a new user, the new user could access the old user's Hail Batch account.

Hail is an open-source, general-purpose, Python-based data analysis tool with additional data types and methods for working with genomic data. Hail relies on OpenID Connect (OIDC) email addresses from ID tokens to verify the validity of a user's domain, but because users have the ability to change their email address, they could create accounts and use resources in clusters that they should not have access to. For example, a user could create a Microsoft or Google account and then change their email to [email protected]. This account can then be used to create a Hail Batch account in Hail Batch clusters whose organization domain is example.org. The attacker is not able to access private data or impersonate another user, but they would have the ability to run jobs if Hail Batch billing projects are enabled and create Azure Tenants if they have Azure Active Directory Administrator access.