The process of creating software that is reliable, effective, and secure from flaws in the underlying codebase is known as secure coding. The security needs are increasing as Android development spreads and becomes more widely used. To safeguard their applications, the data of their users, and the hardware their applications operate on, software developers must take certain security standards into account.
The security specifications for secure coding in Android development, both low-level and high-level development, are described in this section. Topics covered include code integrity, data protection, and incident response.
Code Integrity
- Booting Securely
Make certain that all Android-running devices have a secure boot procedure, which comprises checking the digital signatures of the firmware, kernel, and other essential system components before they are loaded onto a device. This makes it possible to guarantee that the device only loads and runs authenticated applications.
- Compiler Optimizations
When generating your program, use the proper compiler optimizations to prevent exposing weaknesses in the produced code. It’s important to be aware that various compiler optimizations may delete or change the security checks that your code implements, making the application vulnerable.
- Address Space Layout Randomization (ASLR)
By randomizing the memory layout of an application’s address space, ASLR helps to reduce the likelihood of buffer overflow attacks. Make sure that ASLR functionality is implemented into the programs to stop hackers from running code at known memory addresses.
Example in C:
// ASLR can be enabled using the following compiler flag:
// gcc -pie -fPIE file.c- Code Obfuscation
Obfuscate your application’s code to make it more difficult for attackers to reverse-engineer, modify, or tamper with your software. Code obfuscation techniques include renaming classes, methods, and variables, and encrypting string constants.
Data Protection
- In-Transit Data
Protect sensitive data exchanged between the client and server using Transport Layer Security (TLS), such as API requests and responses containing personally identifiable information (PII) or sensitive user data.
OkHttp:
// Use OkHttp to make secure HTTPS requests using TLS
public OkHttpClient.Builder enableTLS(OkHttpClient.Builder builder) {
try {
SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, null, null);
builder.sslSocketFactory(sslContext.getSocketFactory(), new X509TrustManager() {
@Override
public void checkClientTrusted(X509Certificate[] chain, String authType) {}
@Override
public void checkServerTrusted(X509Certificate[] chain, String authType) {}
@Override
public X509Certificate[] getAcceptedIssuers() {
return new X509Certificate[]{};
}
});
} catch (Exception e) {
Log.e("SecureTLS", "Failed to enable TLS", e);
}
return builder;
}- At-Rest Data
Securely keep important information on the device by encrypting it to prevent theft, tampering, or unwanted access. Use the built-in encryption tools in Android, such as shared preferences encryption, room database encryption, and the Android Keystore system, to store cryptographic keys.
Encrypted Shared Preferences:
// Use EncryptedSharedPreferences for securely storing sensitive data
val masterKey = MasterKey.Builder(context)
.setKeyScheme(KeyProperties.KEY_ALGORITHM_AES256_GCM)
.build()
val sharedPreferences = EncryptedSharedPreferences.create(
context,
"secure_prefs",
masterKey,
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)- Temporary Data
By safely erasing or overwriting it after use, you can reduce the amount of private information kept in memory. Avoid utilizing mutable data structures like arrays and think about using Java’s ‘SecureRandom’ to produce random values.
SecureRandom:
SecureRandom secureRandom = new SecureRandom();
byte[] randomBytes = new byte[16];
secureRandom.nextBytes(randomBytes);- Local database
The sqlite database file can be accessed through /data/data/package.id/databases/
- Temp file
The temp files can be accessed through */data/data/package.id/
Authentication and Authorization
- Strengthened Authentication
To guarantee that only authorized users can access important elements in your application, utilize strong authentication procedures. This might entail using the Android Keystore system’s hardware-backed keys, biometrics, or multi-factor authentication (MFA).
- RBAC or role-based Based Access Control
Use role-based access control, which classifies people and resources according to roles and allows for the granting or revocation of access to secure resources based on roles. Limiting user access to select, potentially vulnerable areas of the program can help lower the attack surface.
Network Security
a. Certificate Pinning
To make sure that your application only communicates with reliable services, implement certificate pinning. Certificate pinning reduces the possibility of a man-in-the-middle attack by requiring and binding your app to only accept particular server certificates or public key fingerprints.
OkHttp:
val certificates = listOf(CertificatePinner.Pin.fromCertificatePemResource("<PEM_resource>"))
val pin = CertificatePinner.Builder()
.add("example.com", *certificates.toTypedArray())
.build()
val client = OkHttpClient.Builder()
.certificatePinner(pin)
.build()b. Network Security Configuration
Use the Android Network Security Configuration feature to establish rules and policies for your application’s network connections, such as requiring TLS and pinning certificates.
Example in XML:
<!-- res/xml/network_security_config.xml -->
<network-security-config>
<domain-config>
<domain includeSubdomains="true">example.com</domain>
<pin-set>
<pin digest="SHA-256">7HIpactkIAq2Y49orFO62ou0jxCAH9CWuRxXLkIXELM=</pin>
</pin-set>
</domain-config>
</network-security-config>Incident Response
- Monitoring and Logging
Put in place a reliable logging and monitoring system to track down forensic evidence in the event of a security breach and identify security occurrences in real time. Avoid logging sensitive information since an adversary might find it valuable.
- Updates on Security
Use the most recent security patches, libraries, and best practices to keep your application and development environment up to date. Conduct security audits and assessments on a regular basis to find and patch any potential flaws in your code, dependencies, and device configurations.
- Plan for Security Incident Response
Establish a thorough security incident response plan that outlines the actions to be taken in the case of a security issue, including roles and responsibilities, communication protocols, and post-incident analysis to prevent recurrences.
An all-encompassing strategy is needed for secure coding in Android development, taking into account many factors such as code integrity, data protection, authentication, network security, and incident response. You can make sure your Android applications are strong and resistant to frequent vulnerabilities and attacks by following these security standards and putting the right approaches into practice. To ensure that your critical applications and user data are always secure, stay up-to-date with any new security advice or updates within the Android ecosystem.
Link to Book: Secure Android Development: Best Practices for Robust Apps
