How Insecure Dealer Portals Grant Remote Control Over Thousands of Vehicles

TLDR: A security researcher discovered that a centralized dealer management platform used by major automakers suffered from broken access control and improper authorization. By manipulating invite tokens and exploiting server-side logic flaws, the researcher gained national administrator access, enabling remote vehicle control and access to sensitive customer PII. This research underscores the massive supply chain risk inherent in third-party automotive software that bridges the gap between dealer operations and vehicle telematics.

Automotive security research often focuses on the vehicle itself, specifically the CAN bus, infotainment systems, or mobile app APIs. We rarely look at the dealer management systems that sit behind the scenes, acting as the administrative backbone for thousands of dealerships. These platforms are often massive, interconnected, and poorly secured, yet they hold the keys to vehicle telematics, customer PII, and fleet management. The research presented at DEF CON 2025 proves that you do not need to exploit a zero-day in a vehicle’s firmware to unlock a car from anywhere; you just need to compromise the software the dealer uses to manage it.

The Anatomy of the Dealer Portal Exploit

The target was a centralized dealer management platform that serves as a hub for ordering vehicles, managing leads, and handling service appointments. The platform is accessible via the public internet and is the cornerstone of daily operations for over 1,000 dealerships.

The initial entry point was the invite system. When a new employee joins a dealership, an administrator sends an invite link to their corporate email. This link contains a unique, server-side validated token. The researcher observed that the login page used AngularJS and relied on a server-side API to validate this token. The vulnerability was twofold: the registration form was hidden in the HTML using CSS, and the server-side API failed to properly validate the invite token during the registration process.

By using Chrome DevTools to change the CSS property of the registration form to display: block, the researcher unmasked the hidden form. Submitting the form with a blank or invalid token resulted in a successful account creation because the backend lacked the necessary authorization checks. This is a classic case of Broken Access Control, where the application assumes that if a user can reach the registration endpoint, they are authorized to register.

Escalating to National Admin

Once the researcher had a standard user account, the goal shifted to privilege escalation. The platform used a centralized SSO gateway to manage access across various sub-systems. By intercepting traffic with Fiddler, the researcher identified that the application relied on a SSO_SYS_ID parameter to determine the user's scope.

By replacing the standard dealer-level system ID with a national-level system ID, the researcher successfully bypassed the intended authorization boundaries. This allowed the researcher to impersonate any user, including high-privileged administrators, effectively bypassing both login and two-factor authentication. The impact was total: the researcher gained access to the entire inventory control system, the ability to track vehicles in transit, and access to the finance portal containing sensitive customer contracts and PII.

The Real-World Risk of Interconnected Systems

For a pentester, this research highlights the danger of "obscurity as security." These dealer platforms are not designed with a threat model that accounts for a malicious actor gaining internal access. During the engagement, the researcher demonstrated that they could look up any customer by their VIN, which is easily visible through the windshield of any car in a parking lot. Once the VIN was obtained, the researcher could pull the customer's name, address, phone number, and even their service history.

The most critical finding was the ability to abuse the vehicle enrollment process. Dealers use these systems to pair customers to their new vehicles, which enables the mobile app functionality for remote start and unlock. By abusing the enrollment flow, the researcher could transfer ownership of a vehicle to their own account. This is not just a data breach; it is a physical security failure that allows an attacker to control a vehicle remotely.

Defensive Strategies for Supply Chain Security

Defending against these types of vulnerabilities requires a shift in how we view third-party software. Automakers must treat these dealer management platforms as critical infrastructure. If your organization relies on third-party platforms to handle customer data or vehicle telematics, you must enforce strict Authorization checks at the API level. Never rely on client-side logic or hidden UI elements to restrict access to administrative functions.

Furthermore, implement robust audit logging for all administrative actions. In this case, the researcher noted that while they could view sensitive PII, their actions were logged. While logging did not prevent the breach, it is a necessary component for incident response. If you are a researcher, look for these "glue" applications that connect disparate systems. They are often the weakest link in the supply chain, and they are rarely subjected to the same level of scrutiny as the primary product.

The next time you are on a web application assessment, look for those hidden display: none elements and test the API endpoints behind them. You might find that the entire platform is just waiting for someone to flip a switch.