What an X-linking test does and why it matters for your phone
An X-linking test is a security check that examines whether an app — like Grab, a ride-sharing service — can be tricked into opening links that lead outside the app to malicious websites. When you tap a link inside Grab (say, a promotion or a support page), the app should keep you within its own controlled environment. If the app fails an X-linking test, a bad actor could craft a link that looks like it comes from Grab but actually takes you to a fake login page designed to steal your password.
This test matters because transportation apps handle sensitive information: your location, payment methods, phone number, and ride history. If an attacker can redirect you out of the real app into a fake one, they can capture that data before you realize what happened. The test checks whether the app's developers built proper safeguards to prevent this kind of redirect.
You do not run this test yourself — security researchers and app stores do. But understanding what it checks helps you recognize whether an app you use has been properly vetted, and what to watch for when you are using it.
Key Takeaways
- X-linking tests check whether an app can be tricked into opening external links that bypass the app's security, potentially leading to fake login pages or data theft.
- Transportation apps like Grab are common targets because they store payment methods, location data, and personal information that attackers want to steal.
- You cannot run this test on your own phone, but you can check whether an app has been tested by looking at security certifications or reviews from trusted sources.
- Even if an app passes an X-linking test, you should still avoid tapping suspicious links within the app and never re-enter your password if a link takes you to an unexpected page.
- App stores like Google Play and the Apple App Store conduct their own security reviews, though the depth of X-linking testing varies by platform.
How X-linking vulnerabilities happen in ride-sharing apps
Ride-sharing apps like Grab often include links to promotions, driver support pages, payment help, or terms of service. If the app does not properly validate where those links point, an attacker can inject a malicious link into a message, email, or advertisement that appears to come from Grab. When you tap it, instead of staying inside the real Grab app, you are taken to a website that looks identical to Grab's login screen.
The attacker's fake page captures your email and password. Once they have those credentials, they can log into your real Grab account, change your payment method, or see your ride history and home address. This attack is called deep linking exploitation, and it works because most people assume that tapping a link inside an app keeps them safe.
Transportation apps are targeted more often than other categories because they combine high-value data (payment information, location) with frequent use. A person who uses Grab daily is more likely to tap a link without thinking, and the attacker only needs to succeed once.
What security researchers look for in an X-linking test
When a security researcher tests an app for X-linking vulnerabilities, they examine the app's code and behavior to see whether it validates links before opening them. They check whether the app can be forced to open a link to an external website, whether it properly handles redirects, and whether it warns the user when a link is about to leave the app.
A well-designed app will either prevent external links from opening at all, or it will open them in a separate browser window with a clear visual break from the app itself — so you know you have left the app's protected space. The app should also never ask you to re-enter sensitive information (like your password) after following a link, because that is a sign you may have landed on a fake page.
Researchers also test whether an attacker could use the app's own linking system to redirect you. For example, if Grab has a "share this ride" feature, can an attacker modify that share link to point somewhere malicious? A passing test means the app has thought through these scenarios and built defenses against them.
Where to find information about whether an app has been tested
App stores do not publish detailed X-linking test results for individual apps. However, you can look for security certifications or third-party reviews. Some apps display badges from security firms like Norton, McAfee, or Avast, which means those firms have scanned the app for known vulnerabilities. These scans are not the same as a full X-linking test, but they are a signal that someone has looked at the app's security.
For transportation apps specifically, you can check whether the company publishes a security policy or bug bounty program. Grab, for example, has a public security page where they describe how they handle vulnerabilities. Companies that take security seriously usually publish this information because it builds trust. If a transportation app has no security information at all, that is a reason to be cautious.
You can also read user reviews on the app store, though reviews rarely mention X-linking specifically. Look instead for complaints about unexpected redirects, fake login pages, or account takeovers. If multiple people report being sent to suspicious pages after tapping links in the app, that is a sign the app may not be handling links securely.
What to do if you suspect a malicious link inside an app
If you tap a link in Grab or another transportation app and you are taken to a page that looks like a login screen, stop and close the page when ready. Do not enter your password. Instead, close the browser, go back to your phone's home screen, and open the app fresh by tapping its icon. If you are genuinely logged out, you can log back in from the official app.
If you notice that a link in the app took you somewhere unexpected, or if you see a page that looks almost but not quite like the real Grab website, report it to the company. Grab has a security reporting process on their website where you can describe what happened. Include a screenshot if you can, and describe exactly which link you tapped and where you ended up.
After reporting, change your password for that app even if you did not enter it on the suspicious page. This is a precaution in case the attacker found another way to access your account. Use a password that is unique to that app — never reuse passwords across multiple services, because if one app is compromised, attackers will try that password on your email, banking, and other accounts.
How to reduce your own risk when using transportation apps
The strongest protection is your own behavior. Treat links inside any app with the same caution you would use for links in email or text messages. If a link seems out of place — for example, a promotion that appears in your ride history when you do not remember seeing it before — do not tap it. Instead, go to the app's main menu and navigate to that feature directly.
Never re-enter your password after following a link, even if the page looks official. Legitimate apps do not ask you to log in again after you have already opened the app. If a page asks for your password, your payment information, or your phone number, close it when ready and report it to the company.
Keep your phone's operating system and the app itself updated. Security patches often fix vulnerabilities that attackers could use to exploit X-linking weaknesses. When Google Play or the Apple App Store notifies you that Grab has an update, install it promptly. Updates are not always about new features — they are often about closing security holes.
Frequently Asked Questions
Can I test my own apps for X-linking vulnerabilities?
Not without technical knowledge and specialized tools. X-linking tests require access to the app's code or the ability to intercept and modify network traffic, which is beyond what a typical user can do. If you are concerned about a specific app, contact the company's security team or check whether they have published security test results.
Does passing an X-linking test mean an app is completely safe?
No. An X-linking test checks one specific vulnerability. An app could pass that test but have other security weaknesses, such as weak encryption, insecure storage of passwords, or poor handling of location data. A passing test is a good sign, but it is not a may provide of total safety.
What is the difference between an X-linking test and a regular security scan?
A regular security scan looks for known malware and suspicious code patterns. An X-linking test specifically examines whether the app can be tricked into opening external links that bypass its security. A scan is broader but shallower; an X-linking test is narrower but more focused on one dangerous behavior.
If I use Grab, should I be worried about X-linking attacks?
Grab is a major app used by millions of people, so it is a target for attackers. However, large companies typically invest in security testing, including X-linking tests. Your risk is lower if you follow safe practices: do not tap unexpected links, do not re-enter your password after following a link, and keep the app updated.
What should I do if my Grab account is compromised?
Change your password when ready from the app or the website. Check your payment methods and ride history to see if anything unusual appears. If you see unauthorized rides or payment attempts, contact Grab's support team and report the account compromise. If your payment card was stored in the app, contact your bank as well.