Insecure Direct Object Reference

What are insecure direct object references (IDOR)?

 Insecure direct object reference is a vulnerability that allows attackers to access/manipulate sensitive data by directly accessing database keys, file names, or other identifiers. 

Also known asDirect object reference (DOR) vulnerability, Improper authorization for direct object access, Object-based access control bypass, Vertical/Horizontal privilege escalation, and Insecure resource manipulation vulnerability.

Instead of proper validation, the application trusts that the user has permission to access the data associated with that key or ID. This leaves the door wide open for attackers to access accounts, files, records, or other sensitive information just by guessing or brute forcing IDs.

Some common examples of insecure direct object references include:

Exposed incremental numeric IDs (account numbers, order numbers, etc.)

Hardcoded API keys or credentials in client-side code

Unprotected directory listings that expose file names

Unprotected admin functionality or accounts

To exploit this vulnerability, an attacker must simply manipulate the ID or reference in the web application to access data tied to a different user or account. It's a disturbingly simple but effective attack, which is why insecure direct object references are on the OWASP Top 10 list of web application security risks.

The good news is there are some straightforward ways to prevent this vulnerability. You'll want to implement access control checks, randomize IDs, and validate all user input. Tighten up those references, and you'll plug this hole quickly.

Examples of IDOR

One common example of IDOR is accessing someone else’s private files or records just by changing a number in the URL. Say an app stores files with URLs like,, etc. If there’s no check to ensure you own file #2, you can access it just by entering that URL.

Another IDOR vulnerability allows unauthorized access to sensitive data by guessing or brute-forcing the application's ID. For instance, an app may expose records at,, etc. An attacker could write a script to cycle through numbers until they find records belonging to other users.

Some IDOR issues allow the manipulation of data through direct object references. For example, an app might have a “delete profile” feature at By changing the 1 to another profile ID, an attacker could delete other users’ profiles.

The bottom line is that if an application uses direct references to objects like files, records, or accounts, it needs to verify the user has permission to access or modify those objects. Failing to do so leaves the door open for IDOR, allowing unauthorized access and manipulation of sensitive data. Be on the lookout for these vulnerabilities in your software, and pressure developers to patch IDOR risks whenever they’re discovered. Our personal information is too valuable to leave exposed!

How to Prevent IDOR Vulnerabilities

To prevent IDOR vulnerabilities in your application, there are a few key steps you can take:

Access Control

Implement strong access control checks for all API endpoints and resources. Refrain from assuming that just because users can access one resource, they should have access to related resources. Explicitly check users' permissions for each request and verify their authorization for that specific resource.

Randomize Identifiers

Use randomly generated, opaque identifiers for resources instead of incremental IDs or names that can be easily guessed. This makes it much harder for an attacker to access resources by manipulating IDs.

Validate User Input

Carefully validate all user input for API requests to ensure the input matches the expected format. Don't trust that a user ID, file name, or other parameter is valid just because it was provided in the request. Malicious users may tamper with these values to try and access unauthorized data.

Audit Your Application

Regularly audit your application for IDOR vulnerabilities, especially after any major changes. IDOR issues often arise from subtle oversights, so a fresh set of eyes can help identify any weak spots in your access control or validation logic. You can also use automated scanners to help detect potential IDOR flaws.

Stay Up-to-Date

Keep your application framework and all dependencies up-to-date with the latest versions. IDOR vulnerabilities are frequently disclosed and patched in third-party software libraries. Updating promptly helps ensure you have the latest fixes for any issues.

Following security best practices like these can help reduce the risk of IDOR and keep your users' data safe. Be vigilant and proactively search for any weaknesses that could be exploited.


An IDOR vulnerability can have serious consequences. Once an attacker gains access to sensitive data or resources, the impact can be far-reaching.

Data Breaches

If an IDOR flaw allows access to personal information, financial data, or trade secrets, it can lead to a devastating data breach. Hackers can access and steal hundreds or thousands of sensitive records. This can undermine customer trust, lead to legal penalties, and cost organizations millions.

Account Takeover

If an IDOR vulnerability allows an attacker to access account IDs or manipulate account settings, it can enable account takeover. Hackers may be able to log into user accounts, change passwords, add payment methods, and conduct fraudulent activity. This can have a major impact on both the organization and its users.


In some cases, an IDOR flaw may allow attackers to access and modify website content, enabling defacement. Hackers can replace legitimate content with their messages, images, or videos. While typically low impact, defacement undermines a company’s online reputation and credibility.


Rarely an IDOR vulnerability can be exploited to launch a denial-of-service attack by manipulating or deleting critical resources. For example, an attacker may be able to delete database records, modify configuration files, or manipulate caching mechanisms to disrupt services. Although less common, the impact can be catastrophic.

In summary, IDOR vulnerabilities should be taken very seriously due to their potential impact. Organizations must identify and remediate these flaws to avoid damaging data breaches, account takeovers, website defacements, and denial-of-service disruptions. Proper access control and validation of all user requests can help prevent insecure direct object references.

Frequently Asked Questions (FAQs)

What is Insecure Direct Object Reference (IDOR) in mobile app security?

IDOR is a vulnerability that allows attackers to access sensitive data or resources by manipulating identifiers like database keys or file names. This could lead to unauthorized access to user accounts, files, or other sensitive information in mobile apps.

How can mobile app developers prevent IDOR vulnerabilities?

Mobile app developers should implement strong access controls, validate user input, and randomize identifiers to prevent IDOR. They can also perform regular security audits and use tools like Appknox, which offers advanced security solutions to identify and address vulnerabilities like IDOR.

Can IDOR impact the security of my mobile app users?

Absolutely. If your mobile app is vulnerable to IDOR attacks, attackers could gain unauthorized access to user accounts and personal information or even conduct fraudulent activities on their behalf. This can severely impact user trust and your app's reputation.

How can Appknox help mobile app developers address IDOR vulnerabilities?

Appknox provides powerful security scanning and testing tools to identify IDOR vulnerabilities in your mobile app. With its comprehensive approach to app security, Appknox helps you detect and remediate vulnerabilities like IDOR before attackers can exploit them.

Is IDOR a common threat to mobile apps?

Yes, IDOR is a prevalent vulnerability that mobile app developers should be aware of. Hackers often attempt to exploit IDOR vulnerabilities to gain unauthorized access to valuable data. To mitigate this risk, developers should prioritize security testing and employ tools like Appknox to enhance their app's security posture.


Insecure Direct Object Reference is a critical vulnerability that mobile app developers and owners need to be vigilant about. It's crucial to take proactive steps to prevent IDOR by implementing strong security practices and leveraging tools like Appknox. With Appknox's advanced security solutions, you can identify and mitigate vulnerabilities like IDOR, ensuring the security and trustworthiness of your mobile applications. Protect your users' data and maintain the integrity of your app – explore how Appknox can elevate your app security today.