A Comprehensive Guide to IDOR Vulnerability and Ways to Find It

Quick Summary: IDOR is one of devastating security vulnerabilities that occur due to broken access control in web apps. This vulnerability allows attackers to access critical data after bypassing security mechanisms. Read on to learn more about IDOR, its types, and how to find it to secure your web app. Plus, check out prevention tips to protect your web app against an IDOR security risk.

Today, cybersecurity is a big challenge for organizations. Plus, continuously emerging vulnerabilities pose another threat to the security and integrity of their digital landscape. There are a wide range of vulnerabilities that affect organizations today and one of them is IDOR.

IDOR or Insecure Direct Object Reference is a security flaw that an attacker can exploit to get unauthorized access to a web application and its data. You need to find it and resolve it to prevent security breaches and protect your data from hacking.

In this article, we will understand IDOR vulnerability and how to find it to secure your digital assets. Let’s keep reading for all this information.

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Understanding IDOR Vulnerability

IDOR, a squeezed form of Insecure Direct Object Reference, is an access control implementation flaw. It will allow attackers to exploit insecure object references to gain access to a privileged account.

It is a broken access control vulnerability that occurs when there is a flaw in the implementation of access controls.

Let’s see an example of IDOR vulnerability through a demo web application.

Suppose there is a web application that has a customer account page where information related to different customers is displayed. Users can navigate to the web page using URL:

https://example-application.com/customer_account_info?customer_id=123456

In this URL, “customer_id” refers to the record id for a particular customer. This id is used to fetch a customer’s information from the database in the backend. However, the thing to notice here is that there is a direct reference for this id.

Apparently, the direct reference to customer id makes it susceptible to attacks. How? Because an attacker can easily modify the id reference and get information about other users. For example. The attacker can modify the URL like:

https://example-application.com/customer_account_info?customer_id=145326

After this, the attacker will have access to other customers’ account information.

How Do IDOR Attacks Occur?

IDOR attacks exploit vulnerabilities in applications that improperly handle object references, such as database records, files, or other resources. Here’s how IDOR attacks take place.

Exposure of Object References

Applications often use easily guessable references, like URLs or form parameters to get resource’s accessibility. For example, a URL like `https://example.com/profile?userId=123` directly links to a user's profile based on the `userId` parameter.

Lack of Authorization Checks

If the application fails to verify that the existing user has rights to access or change the resource identified by the reference, attackers can misuse this. For instance, if an attacker has an idea or can guess another user's ID, they might access or alter data they otherwise shouldn't be able to.

Manipulation of References

Attackers misuse the object reference in requests to obtain unauthorized access. By altering URL parameters, form fields, or API calls, they attempt to access other users' data or execute actions on resources for which they don't have any rights.

Predictable or Sequential IDs

If the system uses easily guessable or sequential identifiers (e.g., user IDs that increase by 1), it becomes very simple for attackers to predict and manipulate references to access additional resources.

What are the Different Types of IDOR Attacks?

IDOR vulnerability can allow an attacker to get privileged escalation. Consequently, the attacker will have the necessary access rights to cause havoc in the target system. Moreover, IDOR attacks vary based on various factors. There are four types of these attacks as given below.

Path Traversal

Path traversal, which is also known as directory traversal, is a kind of attack in which the attacker tries to breach a system’s security by manipulating paths. For example, if a vulnerable web app uses a file parameter insecurely, the attacker can modify it with values like “../../../../../etc/password” to gain access to files beyond the root folder.

URL Tampering

Another way to exploit IDOR is URL tampering that doesn’t require specific expertise and can be done easily. This kind of attack is carried out by only changing the value of a URL parameter. The attacker manipulates the query string parameters in a URL. By modifying the URL parameters, attackers can gain unauthorized access to an application or alter the way it behaves.

Modifying Cookie/JSON ID

JSON web tokens and cookies help enhance user experience by offering tailored content. Plus, they are also utilized to track users’ activities on a web application. Servers usually the value of a session ID is stored in a JSON object or a cookie. When there is an IDOR loophole in the application, the attacker can exploit it to alter the value. Consequently, the attacker can gain access to users’ session.

Body Manipulation

It has similarity with URL tampering. The only difference is that the attacker attempts to modify the values in the body instead of an application URL. It means, the attackers can tamper with the values of checkboxes, radio buttons, text-fields, and other form elements. The attacker may also try to change hidden form elements.

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What Should You Do to Find an IDOR Vulnerability?

There is an important question – how and where to find IDOR vulnerability? Finding this vulnerability can be tricky as it can be in more than one place. You need to look for different ways your web application uses user input to point to objects directly. For example, user input could be used to access a file object or fetch user input. Let’s see the different methods to test IDOR weaknesses.

How to find it?

• You can use built-in developer tools in web browsers to look for this IDOR vulnerability. Web browsers offer a rich set of developer tools that are useful in performing security testing. They can help to discover many types of common vulnerabilities.
• Another way you can use to find IDOR vulnerabilities is through automated security testing. There are many automated vulnerability assessment tools available that help to discover a wide range of vulnerabilities. You can also use these tools to discover IDOR security vulnerabilities in your web app. The best part is this method doesn’t require human intervention and even a person without technical knowledge can find vulnerabilities.

Where to check for this vulnerability?

• Check Input Parameters

Imagine there is a URL used to query a database “https://www.examplesite.com/person?person_id=1021” and fetches a person’s information. The ID directly references the database object. In this case, an attacker can manipulate the “person_id” parameter to something like “1022” in the sequence to fetch information for other persons.

Apart from fetching database, the input parameter can also be used to fetch files like in “https://examplesite.com/person_records?pid=1122.pdf” to fetch a person’s record file. Since the user input is directly used to fetch files, it can be manipulated to access file for any other person.

• Test Input Parameters for Database Operations

Now take an example of a web application that takes user input to perform database operations. The best example is CRUD operations. A user provides input used to modify data in database. Suppose there is a web page “https://examplesite.com/modify-person-data" that is used to alter data of a person. It takes ID parameter for a person to modify the relevant data. User input is directly used to modify data. In this case, an attacker can play with user ID to modify data for any other person.

How Can You Prevent Insecure Direct Object Reference Vulnerability?

There are different ways to prevent IDOR vulnerabilities as mentioned below.

Implement Access Control Properly

Access control is a vital functionality for a web application that you must implement properly. By implementing it properly, you can prevent unauthorized access. Access control flaws can enable an attacker to breach the security of your systems to access critical files and data.

Ensure Proper Session Management

Session management helps to keep track of users’ activities once logged in. Plus, it helps to manage their activities. If you fail to implement session management properly, it could risk your web application’s security. An attacker can take advantage of weak session management to launch a session hijacking attack and perform unauthorized actions.

Don’t Make Direct Object References

You can get rid of this security issue by avoiding direct object references in coding. This is known as sloppy coding. It can cause critical vulnerabilities in your web application that attackers can exploit to reach crucial data.

Use Universally Unique Identifier

Web applications that use sequential parameter values like “0001”, “0002”, and more are susceptible to insecure direct object reference attacks. Indeed, an attacker can easily guess these parameters and gain access to crucial data.

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Final Thought

Vulnerabilities are a real challenge for companies that cause various security issues. They open door for malicious actors to reach critical data or damage your digital ecosystem. Hence, it is crucial to find and remediate vulnerabilities.

IDOR is one of those vulnerabilities that allow attackers to gain unauthorized access to your digital asset. Identifying and fixing this vulnerability is critical for securing your digital assets. Vulnerability assessment is an effective way to discover and resolve such security issues.

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