Understanding Certificate Pinning to Combat Man-in-the-Middle Attacks

Strengthening Mobile App Security:

Introduction:

With the explosive growth of mobile app usage, Man-in-the-Middle (MitM) attacks on the API channel between mobile apps and backend servers have become a significant threat to user data and privacy. These attacks allow cybercriminals to intercept and manipulate communications, potentially leading to data theft, unauthorized access, or even denial of service attacks. To combat this rising concern, enterprises need to adopt effective measures to safeguard their mobile applications and protect their organization's data and revenue.

Understanding the MitM Threat:

MitM attacks involve attackers intercepting mobile device communications to gain unauthorized access to sensitive information. Attackers can manipulate messages, steal login details, intercept commercial/personal data, and more. Despite API traffic being encrypted using TLS (Transport Level Security), MitM attackers can insert themselves into the channel, impersonating the legitimate backend server and capturing traffic undetected.

The Role of Certificate Pinning:

Certificate pinning is an effective way to thwart MitM attacks in mobile apps. It restricts communication to servers with a valid certificate matching the expected value (pin). If communication is attempted with any other server, the connection is immediately terminated, preventing unauthorized access. If you want to get started with understanding and implementing certificate pinning, this free Pinning Generator Tool makes it simple to generate and maintain pinning configurations for mobile apps, ensuring that they are kept up to date on Android and iOS.

Static vs. Dynamic Certificate Pinning:

While certificate pinning is useful, static pinning has some drawbacks. Hardcoding pins in the app before release can lead to potential vulnerabilities if private keys are compromised or if changes in encryption algorithms occur. Users must update their apps to ensure security changes take effect. In contrast, dynamic or live pinned certificates from an online service offer a more flexible approach. This allows automatic updates without users needing to install app updates each time there's a change in security infrastructure.

The Barclays Bank Incident:

A disastrous example of static pinning's shortcomings was seen in a Barclays Bank UK incident. The bank's mobile app was pinning an outdated intermediate certificate, causing transaction authentication failures. This resulted in severe financial losses, reputational damage, and impacted numerous business customers.

Emphasizing the Need for Dynamic Pinning:

To mitigate the risks associated with static pinning, mobile app developers should adopt dynamic pinning. This approach ensures that certificates are continually updated, staying ahead of potential cyber threats. It enhances customer trust, as users can have confidence in the mobile application's security and data protection capabilities.

Conclusion:

The massive deployment of mobile apps is presenting new attack surfaces to bad actors and the API channel between the apps and backend services is one of the 5 defined attack surfaces in the ecosystem. Certificate pinning is a critical security measure for protecting mobile apps against MitM attacks. By implementing dynamic pinning instead of static pins, app developers can proactively safeguard user data, enhance customer experience, and maintain their organization's reputation. Trust in mobile security is paramount, and prioritizing privacy and data protection is essential for any business handling sensitive data through mobile applications.