Mobile apps have become a crucial part of our everyday lives. We rely on apps for everything from communication, productivity, entertainment, shopping and more. However, with great utility comes great responsibility. As a mobile app developer, it is your duty to ensure that you build and deploy secure apps that protect user data and privacy. 

In this comprehensive guide, we will walk you through the best practices and tips to secure your mobile apps. Follow these recommendations and you can release apps that are resilient against attacks and unintended data leaks.

The Mobile App Security Threat Landscape

Before we dive into the specific ways to secure your apps, it’s important to understand the kinds of threats and vulnerabilities that exist. Here are some of the main risks to be aware of:

– Malware attacks: Malicious apps or code snippets can be inserted into an app to steal data, spy on users and cause harm. This is done by hacking into the app directly or infiltrating the app store.

– Data leakage: Sensitive user data like usernames, passwords, credit card details etc. can be leaked or exposed through insecure coding practices, unencrypted connections, poor key management and misconfigurations. 

– Identity spoofing: Attackers can pretend to be a legitimate app and trick users into downloading malicious versions, especially from third-party app stores.

– Code tampering: The app code can be decompiled, modified and repackaged by injecting malicious components into a trusted app.

– Man-in-the-middle attacks: Network traffic interception allows attackers to eavesdrop on communications between the app and backend servers/APIs. Unencrypted connections are especially vulnerable.

– Denial-of-service attacks: Floods of traffic can be directed at the app servers to overwhelm and crash them, preventing legitimate access.

– Phishing attacks: Users get duped into entering login credentials and sensitive info into fake apps and websites.

– Reverse engineering: Dedicated hackers can decompile and reverse engineer some aspects of the app to uncover vulnerabilities in the code, encryption keys etc. 

The list above highlights the diversity of risks facing mobile apps today. The attack vectors continue to grow as apps become more sophisticated. So what can developers do to protect their apps and users? Let’s examine the key strategies.

Strategy #1: Build Security Into the SDLC 

The most effective way to ensure app security is to ingrain it throughout your software development lifecycle (SDLC). Security should not be an afterthought to be deal with just before launch. Here are some tips for each stage of app development:

Secure Design 

– Understand the threats specific to the app functionalities, data flows and architecture. Perform comprehensive threat modelling.

– Design appropriate controls, safeguards and contingency measures to mitigate identified risks.

– Adopt secure coding best practices right from the design stage to minimize vulnerabilities in the final code.

Secure Coding

– Use tested and reliable open source components instead of coding critical functionality from scratch.

– Validate all user inputs and sanitize untrusted data to prevent common attacks like code injections, XSS, CSRF etc.

– Encrypt sensitive user data end-to-end, especially when stored or transmitted. Use well-vetted algorithms and key management.

– Use code obfuscation techniques to make reverse engineering harder.

– Mandate secure coding standards across the team and use static/dynamic analysis tools to catch issues early.

Security Testing

– Conduct extensive penetration testing simulating attacks to uncover vulnerabilities. Engage independent security firms for unbiased testing. 

– Perform static and dynamic analysis on source code to detect bugs, malware insertions, backdoors etc.

– Fuzz test by passing invalid, unexpected random data as inputs to find crashes and memory corruption issues.

– Test on jailbroken/rooted devices to gauge the impact of compromised devices.

– Focus on testing authentication, data storage and transmission, inputs, edge cases and integration points.

Incident Response 

– Have an incident response plan ready for a data breach, malware attack or compromise of the app or server environment. 

– Rapidly investigate any reported issue, fix promptly, reset user passwords if needed, notify users transparently if their data is exposed.

– Apply patches quickly when dependencies have publicly disclosed vulnerabilities.

– Work closely with app stores to quickly remove malicious apps impersonating your brand.

By making security a shared responsibility across the SDLC, rather than just a checkpoint before release, you can instill a culture of security. This will lead to inherently more robust apps resistant to most attacks.

Strategy #2: Leverage Platform and OS Security Features

The mobile platforms themselves – Android and iOS – provide many built-in security capabilities you can leverage:

– App Transport Security (ATS) – Enforces secure connections between apps and web services to prevent MITM attacks.

– Address Space Layout Randomization (ASLR) – Randomizes memory addresses used by apps to make exploiting memory corruption bugs difficult. 

– Data execution prevention (DEP) – Prevents execution of code from memory allocated to data, thwarting some code injection attacks.

– Sandboxing – Isolates apps from each other and restricts access to platform resources to contain damage from malware.

– On-device encryption -Filesystem encryption protects sensitive data in case devices are lost or stolen.

– 2-factor authentication – Provides an extra layer of user verification for sensitive transactions. 

– App Attestation – Validates the integrity of an app binary by checking signatures and certificates. Prevents usage of tampered code.

– Smart card and SIM card locking – Integrating locking mechanisms into identity cards makes stolen data unusable.

– Security Enclave Processor – Isolates and protects critical processing like cryptographic operations and Touch ID data.

Activate these options correctly in your app code to leverage the security protections offered by Android and iOS. Stay up-to-date on new security features released and use them promptly.

Strategy #3: Validate Servers and Backends

Mobile apps usually rely on backend servers and cloud services. These integrate with the app through APIs and database/storage systems. It is critical to secure the backend fully, not just the app.

– Harden server configurations by closing unused ports/services, patching systems, encryption of data-at-rest etc. 

– Isolate critical systems like databases behind firewalls to limit access.

– Enforce access control and checks in server code to prevent unauthorized usage of APIs.

– Use OAuth2 standard for authorizing app access to APIs. Generate access tokens with appropriate expiration periods.

– All remote connections must use the latest TLS standards for encryption. Disable old SSL/TLS versions. 

– Conduct regular penetration testing and vulnerability management for server infrastructure.

– Monitor logs, network traffic, anomalous activity to detect attacks and intrusions early.

– Cluster or replicate servers and provision adequate bandwidth for reliability and DDoS resilience.

Neglecting backend security opens up indirect holes in your app for adversaries to exploit. Any external systems your app relies on should be hardened as well.

Strategy #4: Safeguard App Stores and Distribution

The two dominant mobile app stores today are Google Play Store and Apple App Store. Getting listed on these stores provides massive visibility and distribution for your apps. However, app stores also pose some risks:

– Application packages can be tampered with before upload, injecting malware.

– Developer accounts may get compromised allowing attackers to submit malicious versions of your app.

– Rogue apps impersonating your brand may sneak through vetting and make it to the store.

– Reviews and ratings could get manipulated by competitors to rank their apps higher.

Here are some tips to keep your app store presence secure:

– Maintain strict control over developer accounts by using two-factor authentication, complex passwords, role-based access etc.

– Build securely on the development side to minimize tampering risks before upload.

– Analyze changes to account details or app submissions to look for foul play.

– Report fake apps or reviews immediately to the app stores for investigation.

– Consider requiring SMS/email verification before allowing users to post reviews and ratings.

Also ensure secure practices for distributing enterprise or beta apps outside the public stores:

– Code sign your applications and mandate app attestation/verification before installation on user devices.

– Containerize apps developed internally using mobile app management software to prevent IP theft.

– Limit distribution of development builds only to authorized devices which can be remotely wiped if lost.

The app stores are prime targets for malicious actors. Use their security features plus diligent processes to avoid being the next victim.

Strategy #5: Develop a User Security Education Program 

The final piece of the app security puzzle lies with the actual end users. They can either strengthen or weaken overall security through their usage patterns. Educate your users by:

– Providing guidelines on strong password policies and multi-factor authentication best practices.

– Teaching them how to identify and avoid phishing scams, especially through emails/texts with suspicious links.

– Encouraging adoption of device-level security features like fingerprint scanning or facial recognition.

– Detailing which app permissions are needed for required functionality vs. optional ones.

– Notifying users promptly whenever you discover security issues that may impact them. Provide mitigation steps.

– Inform them on how to report bugs, vulnerabilities or abuse related to your app through responsible disclosure.

– Reward security-conscious users through bug bounty programs to build a community of “white hat” app testers.

Empowered users who understand security basics, handle their data hygienically and regularly update devices/apps create a much more formidable defense against rogue actors.

Conclusion

Securing mobile apps is a multilayered approach requiring rigorous focus on security across the SDLC, leveraging platform protections, hardening backend servers, monitoring app stores and educating users. 

While all these steps require significant investment, it is worthwhile to avoid loss of sensitive data, IP theft, legal penalties and reputation damage if your apps get compromised. Keep these best practices in mind and integrate mobile app security into your overall operations for resilient protection against ever-evolving threats.