Critical PII Exposure: Exploiting Broken Object Level Authorization (BOLA) in Travel Infrastructure

At XECbuild, we continuously monitor the evolving landscape of web application vulnerabilities. Despite advancements in modern frameworks, Broken Object Level Authorization (BOLA)—historically known as Insecure Direct Object Reference (IDOR)—remains one of the most prevalent and damaging flaws in enterprise architecture.

Recently, during a targeted security assessment of a major travel and ticketing platform, our methodology uncovered a high-severity BOLA vulnerability. This case study demonstrates how a simple architectural oversight can lead to the catastrophic exposure of Personally Identifiable Information (PII).

🔍 The Reconnaissance: Mapping API Endpoints

During the initial phase of evaluating the platform's infrastructure, the focus was directed toward authenticated data retrieval mechanisms. Specifically, the analysis targeted how the application’s backend API handled transaction logs and failed booking histories.

By routing the application traffic through our proxy architecture, we observed a standard HTTP GET request fetching the booking details. The endpoint relied heavily on a user-supplied parameter: trip-id=[REDACTED].

This behavior immediately flagged a potential vulnerability. When an application relies on a direct, predictable identifier without a corresponding cryptographic validation, it is highly susceptible to manipulation.

⚙️ The Architectural Flaw: Trusting the Client

The core architectural failure here was an absence of server-side state validation. The application verified that a user was authenticated (possessing a valid session token), but it entirely failed to verify if that specific session *owned* the requested resource.

To validate this hypothesis, the intercepted request was modified. By leveraging automated fuzzing tools, the last four digits of the sequential trip-id parameter were incrementally enumerated.

Instead of rejecting the unauthorized requests with an HTTP 403 Forbidden, the backend blindly trusted the manipulated input. Multiple payloads successfully returned an HTTP 200 OK status, accompanied by massive, unformatted JSON blobs containing the full ticketing data of completely unrelated users on the platform.

⚠️ The Business Risk: Massive PII Exposure

The severity of this vulnerability cannot be overstated. By simply iterating through sequential identifiers, an advanced threat actor could programmatically scrape the entire booking database. The exposed JSON payloads contained highly sensitive PII, including:

• Full passenger names and Dates of Birth.
• Detailed travel itineraries, PNRs, and E-Ticket numbers.
• Comprehensive fare breakdowns and payment gateway metadata.
• Direct contact information (email addresses and phone numbers).

In an enterprise environment, this level of exposure constitutes a massive privacy violation, directly contravening data protection regulations (such as GDPR and CCPA), and provides threat actors with the exact data required to execute highly targeted, high-yield phishing and social engineering campaigns.

🏆 Remediation and Core Philosophy

A comprehensive disclosure report, complete with parsed data summaries and a zero-impact Proof of Concept, was securely transmitted to the organization. The security team acknowledged the validity of the critical finding, noting that it was an issue they were currently tracking internally for remediation.

The Key Takeaway for Enterprises:
Never assume an application is verifying permissions simply because a user is logged in. Authentication is not authorization. Organizations must enforce strict, zero-trust server-side authorization checks on every data retrieval request, and legacy sequential IDs should be entirely replaced with cryptographically secure UUIDs.

At XECbuild, we prioritize identifying these critical access control failures before they are weaponized, ensuring enterprise data remains secure.