Office365 Autodiscover Open Redirect Scanner

Office365 Autodiscover is a component of Microsoft's cloud-based email and productivity suite, Office365. It is used by organizations of all sizes to configure email clients and services automatically with minimal user intervention. The feature simplifies the process of configuring email applications by providing necessary configuration settings. Managed by IT administrators, the Autodiscover service is crucial for facilitating the seamless integration of user devices into the organization's email system. This service is especially beneficial for users who frequently travel or use multiple devices. By streamlining setup, it significantly enhances user experience and productivity.

The Open Redirect vulnerability in Office365 Autodiscover occurs when a web application or service allows user-submitted data to determine the destination of a redirection without proper validation. This vulnerability could allow attackers to redirect users to malicious sites that mimic legitimate ones. As a result, it can be used to carry out phishing attacks and obtain sensitive information from users. The vulnerability also poses a risk of attackers modifying data or executing unauthorized operations. If exploited, it could damage both the organization's integrity and user trust.

Technically, the vulnerability exists at the '/autodiscover/autodiscover.json' endpoint in Office365 Autodiscover. The redirection occurs due to improper validation of the 'Protocol' parameter, enabling attackers to inject arbitrary URLs. Malicious actors exploit this vulnerability by crafting URLs that contain a redirect path to an unauthorized destination. Upon accessing the link, the victim is redirected to the backdoor or phishing site created by the attacker. It adds an additional layer of danger as the redirection happens behind the scenes, unknown to the end-user. Proper security measures and validation processes are necessary to mitigate this risk.

The exploitation of this vulnerability can have several severe effects. Primarily, it can lead to phishing attacks where a victim unknowingly provides sensitive data like credentials to attackers. The attacker can manipulate the data flow and execute operations without user consent. Moreover, attackers can install malware or exploit code on user devices during the redirect process. This poses privacy and data security risks by potentially exposing and compromising sensitive organizational data. Furthermore, it undermines user trust, as affected users become more wary of interacting with legitimate systems and services.

REFERENCES

• https://medium.com/@heinjame/office365-open-redirect-from-autodiscover-64284d26c168