OAUTH and OpenID Covert Redirect Vulnerability

Last week a major flaw was reported in implementations of widely used authentication and authorization standards, OAUTH and OpenID. Many consumer and enterprise SaaS apps let users authenticate using these standards. This vulnerability, called “Covert Redirect,” enables attackers to insert themselves into the URL redirect path during the authentication process.

This flaw, though recently reported, isn’t new. Security researchers have noted similar problems in the way OAUTH redirects users after authentication.

One way to fix this is for SaaS apps (OAUTH providers) to have a allow list of URLs for every application that is registered to use OAUTH tokens. Some OAUTH providers are already doing this, and others have said they will do so in the future.

OAUTH and OpenID are important advances in authentication and authorization standards that allow users to securely grant access. They are an important part of the cloud SaaS app ecosystem that allows for SaaS apps to be tied together in a complementary way. However, consumers and enterprise administrators need to be aware of the risks of using OAUTH so that they can monitor and take appropriate action.

Netskope researchers track enterprise cloud apps and their authentication standards. Netskope has identified 300+ cloud apps that support OAUTH or OpenID in various ways, either as a provider or as a consumer. The Netskope Active platform provides administrators visibility into OAUTH usage, which allows them to monitor risks.

As a best practice we also recommend the following:

• As a consumer or end user, regularly review what applications are granted access by visiting your OAUTH providers. All major consumer OAUTH providers – LinkedIn, Facebook, Twitter etc. – give users options to control access to applications. If you see an application that you do not recognize, we recommend you revoke access to that application.
• If you are an enterprise administrator, review the list of OAUTH providers used in your company. Regularly audit which apps have access to those providers.

For the list, or for a complimentary audit of your enterprise cloud apps and how they are using these and other authentication standards, reach out to us at [email protected].

We will continue to track this and other vulnerabilities affecting or adjacent to the enterprise cloud apps that Netskope evaluates.