Partner Article

Five Common Vulnerabilities Found in Today's Mobile Apps

Most people install an app, grant it a few permissions, and never give its security another thought. But behind the interface, mobile apps can carry serious weaknesses and when they're exploited, the consequences tend to land on the people using them, not the developers who built them.

Here's a look at five vulnerabilities that pen testers find repeatedly across mobile apps on both Android and iOS, and what each one actually means if it goes unaddressed.

1. Insecure Data Storage
This is one of the most common findings in mobile app assessments. Apps frequently store sensitive data; tokens, passwords, personally identifiable information, in locations that aren't adequately protected, such as shared preferences, SQLite databases, or external storage. On a rooted or jailbroken device, an attacker can read this data directly.

The real-world consequence is straightforward: if a user's device is compromised or stolen, that data becomes accessible. Even without physical access, malware running on the same device can pull information from insecure storage locations. Good practice requires encrypting sensitive data at rest and keeping it out of world-readable locations entirely.

2. Hardcoded Credentials
Developers sometimes leave API keys, passwords, or secret tokens hardcoded directly in the app's binary. It might happen during development when a key is added for convenience, and it gets shipped to production without being removed. Once the app is published, those credentials are sitting inside a file that anyone can decompile with freely available tools.

This is particularly damaging when the hardcoded credential belongs to a backend service or admin account. An attacker who finds it can interact with the server directly, potentially accessing other users' data or making changes that were never intended to be possible from a client device.

3. Weak or Broken Authentication
Authentication weaknesses show up in several different forms. Some apps rely on client-side checks that can be bypassed without ever touching the server. Others implement token handling poorly, using tokens that don't expire, that aren't invalidated on logout, or that can be reused across different users.

This is where mobile application pen testing adds real value. Testers will probe authentication flows the way a real attacker would by manipulating requests, tampering with tokens, and attempting to access functionality that should be locked away. What looks secure from a normal user journey often falls apart under that kind of scrutiny.

4. Unprotected API Endpoints
A mobile app is, in many ways, just a front end for a server. The actual data lives in the backend, and the app retrieves it through API calls. When those APIs aren't properly secured through missing authentication checks, misconfigured authorisation, or exposed endpoints that the developer assumed users would never find, an attacker doesn't need to interact with the app at all.

They can send requests directly to the API using tools like Burp Suite or Postman. If the server isn't validating who's making the request, or what they're allowed to access, the attacker can retrieve data, modify records, or trigger actions that would be impossible through the intended interface. This type of vulnerability has been behind some significant data breaches in recent years.

5. Insufficient Transport Layer Security
Data in transit between an app and its server should always be encrypted using a properly configured TLS connection. But "should" and "is" don't always line up. Apps sometimes connect over plain HTTP, use outdated TLS versions, or fail to validate server certificates correctly. The last issue is particularly common. An app might use HTTPS but accept any certificate, including one signed by an attacker on the same network.

The consequence here is a man-in-the-middle attack. On an untrusted network, a coffee shop Wi-Fi, for example, an attacker who can intercept traffic will be able to read or modify the data being sent. That might mean session tokens, credentials, or private messages, depending on the app.

What These Vulnerabilities Have in Common
None of the five issues above require a particularly sophisticated attacker to exploit. Tools for decompiling apps, intercepting traffic, and testing API endpoints are widely available and well-documented. The barrier to exploitation is lower than most developers realise.

It's also worth noting that these vulnerabilities don't always announce themselves during testing. A standard QA process won't catch a hardcoded API key or a misconfigured certificate validation. You need someone actively looking for them, working through the app the way an attacker would.

 

This was posted in Bdaily's Members' News section by Helen White .