OAuth Flaw in Travel Service Exposes Millions to Account Theft

Title: Major Account Takeover Vulnerability Discovered in Popular Online Travel Service

Introduction
Cybersecurity researchers have recently revealed a significant account takeover vulnerability affecting a leading online travel service specializing in hotel and car rentals. This vulnerability, which has now been patched, posed a serious risk to millions of users booking airline tickets online. Although the specific name of the service remains undisclosed, it is known to integrate with numerous commercial airline websites, allowing users to seamlessly add hotel bookings to their travel itineraries.

Overview of the Vulnerability
The account takeover vulnerability can be exploited with relative ease through a specially crafted link. This link can be shared through various distribution channels, including email, text messages, and even malicious websites. Users clicking on this link unknowingly risk hijacking their accounts during the login process.

• How the Exploit Works:
  • Users can log into the rental service using their airline credentials.
  • Upon logging in, the service generates a link that redirects users back to the airline’s website for authentication via OAuth.
  • If exploited, attackers can manipulate the authentication response, redirecting it to their own controlled site.

The manipulation occurs at the parameter level, specifically the "tr_returnUrl" parameter, allowing attackers unauthorized access to victims’ accounts and personal information.

Risks and Consequences
Amit Elbirt, a security researcher at Salt Labs, emphasized the stealthiness of the attack, stating that it is challenging to detect due to its use of a legitimate customer domain. This makes it difficult for traditional security measures like domain inspection or blocklisting to identify the threat.

The implications of this vulnerability extend beyond mere data breaches. Attackers could perform actions on behalf of users, such as changing account details or creating orders, highlighting the critical risks inherent in third-party integrations.

The Importance of Robust Security Protocols
Salt Labs has characterized service-to-service interactions as a tempting target for API supply chain attacks. Weak links in these ecosystems are often exploited to gain access to sensitive customer data. Elbirt advises that organizations must adopt stringent security protocols to safeguard users from unauthorized account access and manipulation.

Conclusion
As cyber threats continue to evolve, the discovery of this account takeover vulnerability serves as a wake-up call for both service providers and users. It is essential for organizations to strengthen their security measures and for users to be vigilant when accessing online services.

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