Open Redirect Attacks & Vulnerabilities: How To Avoid It

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What are Open Redirect Attacks

The increasing reliance on digital platforms for communications and transactions has hampered our security than ever. Now, there is an advanced version of these crimes, called cybercrime, so it’s time to make us cyber secure and prioritize cybersecurity just like we secure our financials and confidential details in the real world.

It may sound strange but it’s true because cyberattacks occurs in the fraction of seconds. The stats have shown that a cyberattack takes place every 39 seconds, accounting for 2200 cases daily.

In these cyberattacks, there’s also an overlooked threat called Open Redirect Attack. It’s a part of these cybercrimes and been successfully used by the spammers to hack the user’s account.

Many of you haven’t understood the meaning of open redirect attacks because it’s not even of such importance to spread awareness about it.

So, continue reading this blog.

What is an Open Redirect Attack?

An open redirect attack is a phishing scam that lures victims to a malicious website under the guise of a legitimate one. This method exploits users’ trust in a specific website to redirect them to a site controlled by the attacker, with the primary aim of stealing sensitive information such as login credentials or financial data.

How Open Redirect Attacks Work?

Identifying a Vulnerable Website: Attackers search for websites that allow redirection to external URLs. This functionality is often legitimately used by websites to direct users to different parts of the site or to external resources.

Crafting a Malicious URL: The attacker creates a URL that appears to direct to a legitimate website but instead redirects to a malicious site under the attacker’s control.

For example, a URL like https://www.example.com/redirect?url=https://malicious-site.com might look safe but actually leads to a harmful destination.

Luring the Victim: The attacker employs various methods to convince the victim to click on the malicious URL, such as phishing emails, social engineering, or placing the URL on a compromised or fake website.

Redirecting the Victim: When the victim clicks the malicious URL, they are redirected to the attacker’s website. Because the redirect comes from a trusted site, they may not realize they have been taken to a malicious site.

Stealing Information: Once on the malicious site, the attacker attempts to steal sensitive data like login credentials, financial information, or personal details.

Let’s Understand with the Given Example:

If a legitimate website, such as example.com, has a feature that allows redirection to external URLs without proper validation, an attacker could exploit this by creating a malicious URL.

When a victim clicks this link, they are redirected to a site that, while appearing legitimate, is controlled by the attacker. The victim may be deceived into entering their login information, which the attacker then captures.

Therefore, open redirect attacks manipulate users’ trust in legitimate websites to redirect them to malicious sites where their sensitive information can be compromised.

Websites must thoroughly validate redirection URLs and implement security measures to defend against these attacks.

What are the Types of Redirections?

You might have gain now the understanding of open redirect attack, now it’s time to the four main types of redirection that are performed differently to steal your confidential data. Let’s know all these types:

301 Permanent Redirect: 

A redirect signifies that the requested resource has been moved permanently to a new place. 301 redirect instructs browsers and search engines to update their bookmarks and indexes with this new URL.

This redirect also transfers the SEO value to the latest URL with the previous ranking, which seems organic, plus higher chances of victimizing users and business owners. 

302 Found (or Temporary) Redirect: 

A temporary redirect where the requested is shifted to a new URL for a while. Unlike a 301 redirect, a 302 redirect does not transfer the SEO value to the new URL. As it’s for the short term and fools the users with the scenarios like site maintenance or A/B testing.

303 See Other Redirect: 

A different redirect that instructs the browsers to perform a GET (GETting” data from a source) request to the particular URL. It is often used in response to a POST request to prevent the browser from resubmitting the form data when the page is refreshed. This redirect is not commonly used for general URL redirection purposes.

307 Temporary Redirect: 

Similar to a 302 redirect, a 307 redirect indicates that the requested resource is temporarily located at a different URL. However, a 307 redirect is more explicit in its intent to be temporary. Like a 302 redirect, it does not transfer the SEO value to the new URL.

Recommended: How to Redirect WordPress Website URL from HTTP to HTTPS

Impact of Open Redirect Attacks

No wonder the open redirect attacks are like unknowingly digging your own grave by providing your details and everything to the attackers on malicious websites.

It may sound humorous, but it is a bitter truth because we unknowingly fall into these malicious traps. The impact may vary from person to person and industry to industry.

So, let’s learn about the negative impacts of open redirect attacks.

Financial Loss:

The most significant loss is the financial loss, and why not? Because it’s all about money. These attackers only have an eye on your finances and make you a victim by redirecting you to a fake bank website where users add their card details and everything that they steal.

The credit/debit card details, net banking login details, and everything else get leaked and used to conduct all the fraudulent transactions.

Data Theft:

As explained above, in open redirect attacks, we share sensitive data like usernames, passwords, or personal information. Users are redirected to the sites where we share our data and get into trouble. Attackers steal your data and use it for identity theft and fraud and even sell it to the dark web.

Reputation Damage: 

The business reputation is always on stake, whether online or in the real world. Users shopping on your websites are redirected to the malicious websites where all these fraudulent activities occur, eventually damaging your brand’s reputation and losing customers.

Compromised Security: 

Open redirect attacks also compromise the website’s overall security. The attackers inject malicious code into your website or gain authorized access to sensitive areas. This can lead to further attacks like cross-site scripting (XSS) or SQL injection.

Legal Consequences: 

Many times, open redirect attacks can bring legal consequences. If your company fails to protect its users’ data and it leads to financial loss or identity theft, it may face lawsuits or regulatory fines for non-compliance with data protection laws.

Loss of Trust: 

Ultimately, open redirect attacks lead to a loss of trust between users and the websites they interact with. Users become hesitant to click on links or provide personal information, affecting the overall user experience and potentially harming business relationships.

Therefore, open redirect attacks bring severe consequences ranging from financial loss to the loss of potential customers. Implementing strict security measures to your website is now more important than ever.

How to Test Open Redirect Vulnerability?

While performing open redirect vulnerability test, you have to be careful and notice if the website is allowing any invalidated user input to dominate the redirection behavior. There are few ways you can consider to check the website’s vulnerability:

  • Input Point Identification: Determine the areas on an application or website where a user’s input takes them to another page. This might include URL parameters, form fields or cookies.
  • Creating Malicious URLs: Develop URLs that look real enough only to divert you to another site which is maliciously intended.
  • Submit URL: Feed these manipulated URLs into the input fields of the application or change them so that they match the application’s URL. Check whether it will redirect to the given malicious site without proper validation.
  • Observe Redirection Behavior: Watch out for any invalidated/unsecured inputs leading applications directly to malevolent internet sites.
  • Redirection Checks with Other Methods: Look at open redirects other than main ones like using HTTP headers manipulation and JavaScripts to identify weaknesses of sites.
  • Determine Impact: Confirm if redirection took you where it was meant ensuring nothing has been leaked and no sensitive data has been taken away from your system.

Recommended: What is the 401 Unauthorized Access Error? Top 5 Fixes to Resolve It?

What are the Parameters to Look for Open Redirect?

Open redirects are merely responsible for framing the applications and web pages to redirect users to malicious sites chosen by the attacker.

The following parameters are to be considered when assessing the open redirect on any website or application:

  • URL Validation: Websites and applications should validate the URL parameter to ensure they are redirected to a valid and safe place. 
  • Whitelist of Allowed URL: The URL to which the application redirects can be implemented in an allow list manner to avoid arbitrary URLs.
  • HTTP Referrer Header: The HTTP referrer header checks that the request is redirected and comes from known sources. 
  • CSRF Tokens: These tokens are crucial in redirect requests. By including them, the application can verify the request’s legitimacy, preventing hijacking attempts by outsiders. 
  • Session Management: The application session management should include redirecting activity to avoid unauthorized access. 
  • User Input Sanitization:  Sanitize the user input to avoid the use of special characters or escape the character .
  • Logging and Monitoring: This is a proactive measure against open redirect vulnerabilities. By logging and monitoring activity on these vulnerabilities, we can detect and catch attackers in advance, preventing exploitation. 
  • Security Headers: The application redirects to a high-risk URL with security header measures such as CSP. There can be awareness created by CSP about the applications’ allowed and disallowed URLs.

Therefore, open redirect vulnerabilities can be identified by regular security audits, code reviews, and scanning for commonly fusible certificates, which are essential for larger applications.

Scenarios for Exploiting Open Redirect Vulnerabilities

Various scenarios can be used by attackers to exploit open redirect vulnerabilities and deceive users into visiting phishing pages or malicious websites.

Below are some common scenarios of exploiting open redirects.

Phishing Attacks:

Attackers can create a phishing email that has a link which looks legitimate like a popular service or bank site. In reality, the link will actually take the user to another website with intentions of stealing their login credentials and other personal details.

Malware Distribution:

Malicious individuals can make use of open redirect vulnerabilities to send users to malicious websites that host malware. Those sites may employ operating systems or browser exploits so as to have malware installed on user’s device.

SEO Poisoning:

Search engine results manipulation (SEO) is a technique through which attackers manipulate search engines in order to increase ranking.

Recommended: Boost SEO Visibility with Trusted SSL/TLS Certificates

Attackers use this method by redirecting search engine crawlers towards malicious webpages which increases their rank on search result pages making more people access these harmful contents.

Identity Theft:

User authentication tokens and session cookies are what attackers may get away with by exploiting open redirects. Impersonating the victims’ identities on valid web portals is possible when they are misdirected towards evil internet resources by this trickery.

How to Prevent the URL Open Redirect Vulnerability?

Prevention is better than cure, so try to avoid being falling into the trap of open redirect vulnerability with the below listed ways:

Validate and Sanitize Input:

Make sure that any user-inputted data get validated and sanitized (for instance by checking for malicious URLs) to avert the use of such data on unsafe places.

Use Whitelists:

To maintain the white list, having URLs or URL patterns that your application can redirect are very useful. Use this whitelist to whitelist the following URLS that the redirects should be for.

Encode Output:

Any URL parameter received should be URL encoded before shipping redirect response ahead. Therefore, such a mechanism can effectively cut malicious URLs out and save us from such an occurrence.

Use Safe Redirect Methods:

However, instead of redirecting to user-provided URLs directly, choose safer methods. For example, profit from the internal map of URL transition to redirect.

Limit Redirect Chains: 

Keep the chain of redirections short so as not to give a chance to hide actual harmful domains.

Monitor and Log: 

Keep an eye on your app for any suspicious redirect activity feed, research your code, and look for any possible abuse of the vulnerability.

Educate Users: 

Educate users on the fact that clicking on untrusted links may be dangerous for the computer, and teach them a routine for determining the trustworthiness and authority of a particular web address.

Concluding Thoughts:

Indeed, open redirects pose a great threat to users and businesses alike. They direct you to malicious websites and lead to data loss or, even worse, many times.

Though you have a significant understanding of this, it’s still better to consult a cybersecurity specialist to guard your online property.

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Janki Mehta

Janki Mehta

Janki Mehta is a Cyber-Security Enthusiast who constantly updates herself with new advancements in the Web/Cyber Security niche. Along with theoretical knowledge, she also implements her practical expertise in day-to-day tasks and helps others to protect themselves from threats.