The apps on a mobile device usually contain information that is private, both personal and business related. Security has really become a critical issue for mobile applications. Over 75% of mobile apps are discovered to have at least one security vulnerability in the year 2024.
I. Insecure Data Storage#
Insecure data storage is one of the major mobile security problems. This is when an application stores sensitive information such as passwords, tokens, personal information, etc., on a device without any protection or encryption at all. Insecure storage is very common and easy to exploit, especially on rooted/jailbroken devices, as they can bypass built-in encryption safeguards. For instance, one study found that a shocking 92% of mobile apps use secure encryption techniques incorrectly, meaning the data believed to be encrypted can be decoded by the attackers.
1. Risks#
Sensitive user data stored in plaintext or weakly encrypted can be extracted by anyone interacting with the device’s file system via malware, exploiting shared storage, or simply hooked up to a PC. Essentially, any cached passwords, session tokens, or personal files not properly encrypted are at risk of theft and misuse.
2. Example#
Starbucks mobile application, which in early 2014 was found storing users’ usernames, email addresses, and passwords in plaintext on the device. An attacker could easily connect the phone to a computer and read the files to hijack user accounts. The incident underscored why no app should ever store credentials or other secrets in plaintext. All sensitive data if it must be stored locally should be encrypted with strong keys, and ideally kept in secure system areas rather than keeping it on the file system.
II. Weak Authentication and Authorization#
Weak authentication method or bad authorization check causes access vulnerabilities, leaving a space for unauthorized persons. It includes weak passwords, lack of multi-factor authentication, and not protecting user roles/permissions on a server. Password policies that are too weak or local storage instead of secure tokens make brute-forcing logins easier or stealing credentials.
1. Risks#
Weak authentication systems could result in impersonating users for privilege escalation by attackers. Server-side authorization verification absence may allow a malicious user to invoke admin functions by altering network requests. Absence of account lockout and weak password requirements enables brute-force attacks for cracking logins. Impact could be grave: unauthorized access to personal data; fraudulent transactions; or manipulation of application data. In short, broken auth could undermine the whole app security and lets attackers bypass logins or abuse higher-level privileges.
2. Example#
An example of poor security is a deal with SMS for two-factor authentication. The millions of one-time passcode using SMS messages recently exposed in a breach at a telco in late 2024 made it possible for attackers to hijack accounts protected only by SMS verification. It illustrates why apps handling sensitive data are encouraged to take on more robust authentication, like authenticator apps or hardware tokens, instead of SMS. There were also once cases of mobile banking applications that only performed validation rules for user roles as regards clients. Secure app design must be desined on rigorous authentication and stringent server-side authorization checks.
III. Insecure Communication#
Mobile applications generally communicate with backend servers via the Internet, and communicating without fully security could lead the attackers to intercept it. Insecure communication essentially means that an app sends sensitive information over strong protocols, but mostly without encryption. A recent security report claimed that more than 35% of mobile apps send sensitive user data unencrypted, opening them up to possible eavesdropping. Some apps still communicate over plain-text HTTP instead of HTTPS for network calls or accept every SSL/TLS certificate without validation. In one of the documented cases, a mobile banking application was found to be communicating with its server using plain HTTP, putting users’ financial information in obvious risk. This mistake allows an adversary on the same network or malicious Wi-Fi hotspot to perform a Man-in-the-Middle (MITM) attack and spy on or even modify the information exchanged between the app and server.
1. Risks#
When communication is compromised by encryption and integrity protection, attackers can perform interception to steal credentials, session tokens, and private information. They can also use alteration on the median to modify the data. Common scenarios include MITM scenarios through insecure Wi-Fi networks. Without HTTPS (SSL/TLS) and certificate validation, the app cannot be secure talking to the real server. In short, unsecured connections expose the user to network-level attacks, defeating whatever other defenses the application might put in place.
2. Example#
Any application transmitting data over HTTP instead of HTTPS. For instance, a messaging app or payment application that isn’t mandating TLS encryption. Then, an attacker connected to the same public Wi-Fi could easily intercept traffic from the app and read whatever messages or credit card numbers being sent. Another example is an app that does not validate SSL certificates. Attackers exploit this by using a self-signed certificate in a MITM proxy. The app will see it as a secure connection while in fact, the attacker can read and manipulate everything. Always use HTTPS with strict certificate validation for all app communications.
IV. Reverse Engineering#
Mobile applications (especially Android APKs) can be reverse-engineered, allowing an attacker to inspect the source code, find hidden logic, and extract any embedded secrets. There are freely available tools to decompile apps, and if code is not hidden, a determined attacker can learn a great deal about how an app works. Reverse engineering is likely the first step hackers take to identify potential vulnerabilities or to look for ways to bypass client-side security controls.
When the code is understood, if any weaknesses are found, those might be exploited in real-time through the app. A related issue is code tampering. Modification of the app’s binary, or injecting malicious code into it, and redistribution of the process is in poor security definition. Without safeguards against copying the code, modifying it, or using it in some way that benefits an attacker, malicious app discoverability in the Android ecosystem is high.
V. Insecure Third-Party Libraries#
Modern applications depend on 3rd party libraries and SDKs for functionality that include analytics, advertisements, social logins, among other things having possible vulnerabilities or containing some malicious code. Whenever a library is found to be either outdated or unpatched, it basically serves as a backdoor for attackers.
1. Risks#
The developers may import security problems into their applications by using unverified or outdated libraries. Such issues could later lead the application to be attacked or to suffer from data breaches through injection and remote execution. Not updating the libraries in good time when any security patch is released leaves one behind the curve and opens the known bugs to exploitation by attackers. Integrating an unauthorized library without verifying its source or assessing its behavior is game that could result in introducing malicious code.
2. Example#
The Log4j library vulnerability (Log4Shell) that attracted lots of attention in late 2021 is a highly popular logging library with a mix of usages in backend and once in a while mobile. Many mobile applications have been indirectly impacted as those had backends and embedded components that were using Log4j and exploitation would lead to a remote code execution. These addiction underscore the necessity of scrutinizing and monitoring third-party components. Uphold ever credible libraries, paying attention to vulnerability announcements (CVEs), and ensuring a rapid update and patch of those libraries as soon as a security issue comes to light.
VI. Best Practices for Mitigation#
To build secure mobile applications, developers should use this defense mechanism approach. Below are some best practices and mitigation strategies that go with some common vulnerabilities that were discussed:
Encrypt sensitive data: Use strong algorithms to encrypt personal or credential data anywhere in the file system, use platform security features (Android Keystore, iOS Keychain) for managing encryption keys, such that even if breaches the file system, access the data, but cannot decrypt without the key. Also avoid keeping data unnecessarily.
Implement robust authentication: Force strong password policy such as minimum length, complexity, and require MFA for sensitive operations. Do not allow weak PINs or hard coded passwords. Whenever possible, secure authentication tokens should be used instead of storing actual passwords on the device. Consider using biometric (fingerprint/FaceID) authentication as second factor (with fallback to strong PIN/password) to make it stronger.
Use secure communication protocols: Never communicate via HTTP (TLS) for any network traffic. In doing this, configure your app to reject invalid certificates, and to make use of certificate pinning against MITM attacks. Ensure that sensitive data won’t sent in plaintext. Use the latest TLS versions and strong cipher suites to encrypt data in transmission.
Encapsulate and protect the code: Make it as difficult as possible for an attacker to reverse-engineer your app. Create runtime integrity checks that verify if the app binary has been checked or if it is running in a rooted/jailbroken environment. Making sure that while your application is not entirely protected, it would take a lot of effort from the attackers to use it.
Audit and update third-party libraries regularly: Maintain up-to-date inventory for all third-party SDKs, libraries in your project. Keep track of security advisories for the vulnerabilities. Prefer libraries maintained actively. Check libraries/SDKs before adding them: use code from reputable sources; read reviews or research not to find hidden malicious behavior. Also, removing unnecessary dependencies reduces attack risks.
Manage sessions securely: Use random session tokens transmitted only over encrypted channels. Expire them after a reasonable period of inactivity, and make sure the token is invalidated absolutely upon logout. Shortening the lifespan of session tokens and limiting their breadth will help mitigate the damage caused by session hijacking.
Conduct thorough security testing: Run the application and checks at runtime security issues, and regular penetration tests with the mind of an attacker. Use tools and frameworks that systematically check for the issues most commonly discussed above: insecure storage, weak authentication, poor encryption, etc. Do code reviews keeping security in mind and third-party audits to catch what you might have missed.
VII. Conclusion#
There are quite a number of mobile security vulnerabilities that present significant risks to both users and organizations but can easily be mitigated through the right awareness and practices. It requires not only a technical necessity but also a business imperative since it will help maintain user trust and compliance with the regulations of data protection.
In summary, developing a secure mobile app requires a continuous commitment to best practices and up-to-date techniques. Stay informed about emerging threats, follow guidance and security checklists, and never assume your app is too small or insignificant to be targeted. Mobile security must remain a top priority, and proactive mitigation are key to staying ahead of attackers. By eliminating the common vulnerabilities and rigorously testing your app, you can significantly reduce the risk of security incidents. In today’s world, prioritizing mobile security is an investment in both the longevity and the reputation of your application.
