Mejoras de seguridad

Android mejora continuamente sus funciones y ofertas de seguridad. Consulta las listas de mejoras por versión en el panel de navegación izquierdo.

Android 14

Every Android release includes dozens of security enhancements to protect users. Here are some of the major security enhancements available in Android 14:

  • Hardware-assisted AddressSanitizer (HWASan), introduced in Android 10, is a memory error detection tool similar to AddressSanitizer. Android 14 brings significant improvements to HWASan. Learn how it helps prevent bugs from making it into Android releases, HWAddressSanitizer
  • In Android 14, starting with apps that share location data with third-parties, the system runtime permission dialog now includes a clickable section that highlights the app's data-sharing practices, including information such as why an app may decide to share data with third parties.
  • Android 12 introduced an option to disable 2G support at the modem level, which protects users from the inherent security risk from 2G's obsolete security model. Recognizing how critical disabling 2G could be for enterprise customers, Android 14 enables this security feature in Android Enterprise, introducing support for IT admins to restrict the ability of a managed device to downgrade to 2G connectivity.
  • Added support to reject null-ciphered cellular connections, ensuring that circuit-switched voice and SMS traffic is always encrypted and protected from passive over-the-air interception. Learn more about Android's program to harden cellular connectivity.
  • Added support for multiple IMEIs
  • Since Android 14, AES-HCTR2 is the preferred mode of filenames encryption for devices with accelerated cryptography instructions.
  • Cellular connectivity
  • Documentation added for Android Safety Center
  • If your app targets Android 14 and uses Dynamic Code Loading (DCL), all dynamically-loaded files must be marked as read-only. Otherwise, the system throws an exception. We recommend that apps avoid dynamically loading code whenever possible, as doing so greatly increases the risk that an app can be compromised by code injection or code tampering.

Check out our full AOSP release notes and the Android Developer features and changes list.

Android 13

Every Android release includes dozens of security enhancements to protect users. Here are some of the major security enhancements available in Android 13:

  • Android 13 adds multi-document presentation support. This new Presentation Session interface enables an app to do a multi-document presentation, something which isn't possible with the existing API. For further information, refer to Identity Credential
  • In Android 13, intents originating from external apps are delivered to an exported component if and only if the intents match their declared intent-filter elements.
  • Open Mobile API (OMAPI) is a standard API used to communicate with a device's Secure Element. Before Android 13, only apps and framework modules had access to this interface. By converting it to a vendor stable interface, HAL modules are also capable of communicating with the secure elements through the OMAPI service. For more information, see OMAPI Vendor Stable Interface.
  • As of Android 13-QPR, shared UIDs are deprecated. Users of Android 13 or higher should put the line `android:sharedUserMaxSdkVersion="32"` in their manifest. This entry prevents new users from getting a shared UID. For further information on UIDs, see App signing.
  • Android 13 added support Keystore symmetric cryptographic primitives such as AES (Advanced Encryption Standard), HMAC (Keyed-Hash Message Authentication Code), and asymmetric cryptographic algorithms (including Elliptic Curve, RSA2048, RSA4096, and Curve 25519)
  • Android 13 (API level 33) and higher supports a runtime permission for sending non-exempt notifications from an app. This gives users control over which permission notifications they see.
  • Added per-use prompt for apps requesting access to all device logs, giving users the ability to allow or deny access.
  • introduced the Android Virtualization Framework (AVF), which brings together different hypervisors under one framework with standardized APIs. It provides secure and private execution environments for executing workloads isolated by hypervisor.
  • Introduced APK signature scheme v3.1 All new key rotations that use apksigner use the v3.1 signature scheme by default to target rotation for Android 13 and higher.

Check out our full AOSP release notes and the Android Developer features and changes list.

Android 12

Todas las versiones de Android incluyen docenas de mejoras de seguridad para proteger a los usuarios. Estas son algunas de las principales mejoras de seguridad disponibles en Android 12:

  • Android 12 introduce la API de BiometricManager.Strings, que proporciona cadenas localizadas para las apps que usan BiometricPrompt para la autenticación. Estas cadenas están diseñadas para tener en cuenta el dispositivo y proporcionar más especificidad sobre qué tipos de autenticación se pueden usar. Android 12 también incluye compatibilidad con sensores de huellas dactilares debajo de la pantalla.
  • Se agregó compatibilidad con sensores de huellas dactilares debajo de la pantalla
  • Introducción al lenguaje de definición de la interfaz de Android de huella digital (AIDL)
  • Compatibilidad con el nuevo AIDL de Face
  • Introducción de Rust como lenguaje para el desarrollo de la plataforma
  • Se agregó la opción para que los usuarios otorguen acceso solo a su ubicación aproximada.
  • Se agregaron indicadores de privacidad en la barra de estado cuando una app usa la cámara o el micrófono.
  • Private Compute Core (PCC) de Android
  • Se agregó una opción para inhabilitar la compatibilidad con 2G

Android 11

Todas las versiones de Android incluyen docenas de mejoras de seguridad para proteger a los usuarios. Para ver una lista de algunas de las principales mejoras de seguridad disponibles en Android 11, consulta las Notas de la versión de Android.

Android 10

Every Android release includes dozens of security enhancements to protect users. Android 10 includes several security and privacy enhancements. See the Android 10 release notes for a complete list of changes in Android 10.

Security

BoundsSanitizer

Android 10 deploys BoundsSanitizer (BoundSan) in Bluetooth and codecs. BoundSan uses UBSan's bounds sanitizer. This mitigation is enabled on a per-module level. It helps keep critical components of Android secure and shouldn't be disabled. BoundSan is enabled in the following codecs:

  • libFLAC
  • libavcdec
  • libavcenc
  • libhevcdec
  • libmpeg2
  • libopus
  • libvpx
  • libspeexresampler
  • libvorbisidec
  • libaac
  • libxaac

Execute-only memory

By default, executable code sections for AArch64 system binaries are marked execute-only (nonreadable) as a hardening mitigation against just-in-time code reuse attacks. Code that mixes data and code together and code that purposefully inspects these sections (without first remapping the memory segments as readable) no longer functions. Apps with a target SDK of Android 10 (API level 29 or higher) are impacted if the app attempts to read code sections of execute-only memory (XOM) enabled system libraries in memory without first marking the section as readable.

Extended access

Trust agents, the underlying mechanism used by tertiary authentication mechanisms such as Smart Lock, can only extend unlock in Android 10. Trust agents can no longer unlock a locked device and can only keep a device unlocked for a maximum of four hours.

Face authentication

Face authentication allows users to unlock their device simply by looking at the front of their device. Android 10 adds support for a new face authentication stack that can securely process camera frames, preserving security and privacy during face authentication on supported hardware. Android 10 also provides an easy way for security-compliant implementations to enable app integration for transactions such as online banking or other services.

Integer Overflow Sanitization

Android 10 enables Integer Overflow Sanitization (IntSan) in software codecs. Ensure that playback performance is acceptable for any codecs that aren't supported in the device's hardware. IntSan is enabled in the following codecs:

  • libFLAC
  • libavcdec
  • libavcenc
  • libhevcdec
  • libmpeg2
  • libopus
  • libvpx
  • libspeexresampler
  • libvorbisidec

Modular system components

Android 10 modularizes some Android system components and enables them to be updated outside of the normal Android release cycle. Some modules include:

OEMCrypto

Android 10 uses OEMCrypto API version 15.

Scudo

Scudo is a dynamic user-mode memory allocator designed to be more resilient against heap-related vulnerabilities. It provides the standard C allocation and deallocation primitives, as well as the C++ primitives.

ShadowCallStack

ShadowCallStack (SCS) is an LLVM instrumentation mode that protects against return address overwrites (like stack buffer overflows) by saving a function's return address to a separately allocated ShadowCallStack instance in the function prolog of nonleaf functions and loading the return address from the ShadowCallStack instance in the function epilog.

WPA3 and Wi-Fi Enhanced Open

Android 10 adds support for the Wi-Fi Protected Access 3 (WPA3) and Wi-Fi Enhanced Open security standards to provide better privacy and robustness against known attacks.

Privacy

App access when targeting Android 9 or lower

If your app runs on Android 10 or higher but targets Android 9 (API level 28) or lower, the platform applies the following behavior:

  • If your app declares a <uses-permission> element for either ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION, the system automatically adds a <uses-permission> element for ACCESS_BACKGROUND_LOCATION during installation.
  • If your app requests either ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION, the system automatically adds ACCESS_BACKGROUND_LOCATION to the request.

Background activity restrictions

Starting in Android 10, the system places restrictions on starting activities from the background. This behavior change helps minimize interruptions for the user and keeps the user more in control of what's shown on their screen. As long as your app starts activities as a direct result of user interaction, your app most likely isn't affected by these restrictions.
To learn more about the recommended alternative to starting activities from the background, see the guide on how to alert users of time-sensitive events in your app.

Camera metadata

Android 10 changes the breadth of information that the getCameraCharacteristics() method returns by default. In particular, your app must have the CAMERA permission in order to access potentially device-specific metadata that is included in this method's return value.
To learn more about these changes, see the section about camera fields that require permission.

Clipboard data

Unless your app is the default input method editor (IME) or is the app that currently has focus, your app cannot access clipboard data on Android 10 or higher.

Device location

To support the additional control that users have over an app's access to location information, Android 10 introduces the ACCESS_BACKGROUND_LOCATION permission.
Unlike the ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION permissions, the ACCESS_BACKGROUND_LOCATION permission only affects an app's access to location when it runs in the background. An app is considered to be accessing location in the background unless one of the following conditions is satisfied:

  • An activity belonging to the app is visible.
  • The app is running a foreground service that has declared a foreground service type of location.
    To declare the foreground service type for a service in your app, set your app's targetSdkVersion or compileSdkVersion to 29 or higher. Learn more about how foreground services can continue user-initiated actions that require access to location.

External storage

By default, apps targeting Android 10 and higher are given scoped access into external storage, or scoped storage. Such apps can see the following types of files within an external storage device without needing to request any storage-related user permissions:

To learn more about scoped storage, as well as how to share, access, and modify files that are saved on external storage devices, see the guides on how to manage files in external storage and access and modify media files.

MAC address randomization

On devices that run Android 10 or higher, the system transmits randomized MAC addresses by default.
If your app handles an enterprise use case, the platform provides APIs for several operations related to MAC addresses:

  • Obtain randomized MAC address: Device owner apps and profile owner apps can retrieve the randomized MAC address assigned to a specific network by calling getRandomizedMacAddress().
  • Obtain actual, factory MAC address: Device owner apps can retrieve a device's actual hardware MAC address by calling getWifiMacAddress(). This method is useful for tracking fleets of devices.

Non-resettable device identifiers

Starting in Android 10, apps must have the READ_PRIVILEGED_PHONE_STATE privileged permission in order to access the device's non-resettable identifiers, which include both IMEI and serial number.

If your app doesn't have the permission and you try asking for information about non-resettable identifiers anyway, the platform's response varies based on target SDK version:

  • If your app targets Android 10 or higher, a SecurityException occurs.
  • If your app targets Android 9 (API level 28) or lower, the method returns null or placeholder data if the app has the READ_PHONE_STATE permission. Otherwise, a SecurityException occurs.

Physical activity recognition

Android 10 introduces the android.permission.ACTIVITY_RECOGNITION runtime permission for apps that need to detect the user's step count or classify the user's physical activity, such as walking, biking, or moving in a vehicle. This is designed to give users visibility of how device sensor data is used in Settings.
Some libraries within Google Play services, such as the Activity Recognition API and the Google Fit API, don't provide results unless the user has granted your app this permission.
The only built-in sensors on the device that require you to declare this permission are the step counter and step detector sensors.
If your app targets Android 9 (API level 28) or lower, the system auto-grants the android.permission.ACTIVITY_RECOGNITION permission to your app, as needed, if your app satisfies each of the following conditions:

  • The manifest file includes the com.google.android.gms.permission.ACTIVITY_RECOGNITION permission.
  • The manifest file doesn't include the android.permission.ACTIVITY_RECOGNITION permission.

If the system-auto grants the android.permission.ACTIVITY_RECOGNITION permission, your app retains the permission after you update your app to target Android 10. However, the user can revoke this permission at any time in system settings.

/proc/net filesystem restrictions

On devices that run Android 10 or higher, apps cannot access /proc/net, which includes information about a device's network state. Apps that need access to this information, such as VPNs, should use the NetworkStatsManager or ConnectivityManager class.

Permission groups removed from UI

As of Android 10, apps cannot look up how permissions are grouped in the UI.

Removal of contacts affinity

Starting in Android 10, the platform doesn't keep track of contacts affinity information. As a result, if your app conducts a search on the user's contacts, the results aren't ordered by frequency of interaction.
The guide about ContactsProvider contains a notice describing the specific fields and methods that are obsolete on all devices starting in Android 10.

Restricted access to screen contents

To protect users' screen contents, Android 10 prevents silent access to the device's screen contents by changing the scope of the READ_FRAME_BUFFER, CAPTURE_VIDEO_OUTPUT, and CAPTURE_SECURE_VIDEO_OUTPUT permissions. As of Android 10, these permissions are signature-access only.
Apps that need to access the device's screen contents should use the MediaProjection API, which displays a prompt asking the user to provide consent.

USB device serial number

If your app targets Android 10 or higher, your app cannot read the serial number until the user has granted your app permission to access the USB device or accessory.
To learn more about working with USB devices, see the guide on how to configure USB hosts.

Wi-Fi

Apps targeting Android 10 or higher cannot enable or disable Wi-Fi. The WifiManager.setWifiEnabled() method always returns false.
If you need to prompt users to enable and disable Wi-Fi, use a settings panel.

Restrictions on direct access to configured Wi-Fi networks

To protect user privacy, manual configuration of the list of Wi-Fi networks is restricted to system apps and device policy controllers (DPCs). A given DPC can be either the device owner or the profile owner.
If your app targets Android 10 or higher, and it isn't a system app or a DPC, then the following methods don't return useful data:

Android 9

Todas las versiones de Android incluyen docenas de mejoras de seguridad para proteger a los usuarios. Para obtener una lista de algunas de las principales mejoras de seguridad disponibles en Android 9, consulta las Notas de la versión de Android.

Android 8

Every Android release includes dozens of security enhancements to protect users. Here are some of the major security enhancements available in Android 8.0:

  • Encryption. Added support to evict key in work profile.
  • Verified Boot. Added Android Verified Boot (AVB). Verified Boot codebase supporting rollback protection for use in boot loaders added to AOSP. Recommend bootloader support for rollback protection for the HLOS. Recommend boot loaders can only be unlocked by user physically interacting with the device.
  • Lock screen. Added support for using tamper-resistant hardware to verify lock screen credential.
  • KeyStore. Required key attestation for all devices that ship with Android 8.0+. Added ID attestation support to improve Zero Touch Enrollment.
  • Sandboxing. More tightly sandboxed many components using Project Treble's standard interface between framework and device-specific components. Applied seccomp filtering to all untrusted apps to reduce the kernel's attack surface. WebView is now run in an isolated process with very limited access to the rest of the system.
  • Kernel hardening. Implemented hardened usercopy, PAN emulation, read-only after init, and KASLR.
  • Userspace hardening. Implemented CFI for the media stack. App overlays can no longer cover system-critical windows and users have a way to dismiss them.
  • Streaming OS update. Enabled updates on devices that are are low on disk space.
  • Install unknown apps. Users must grant permission to install apps from a source that isn't a first-party app store.
  • Privacy. Android ID (SSAID) has a different value for each app and each user on the device. For web browser apps, Widevine Client ID returns a different value for each app package name and web origin. net.hostname is now empty and the dhcp client no longer sends a hostname. android.os.Build.SERIAL has been replaced with the Build.SERIAL API which is protected behind a user-controlled permission. Improved MAC address randomization in some chipsets.

Android 7

Every Android release includes dozens of security enhancements to protect users. Here are some of the major security enhancements available in Android 7.0:

  • File-based encryption. Encrypting at the file level, instead of encrypting the entire storage area as a single unit, better isolates and protects individual users and profiles (such as personal and work) on a device.
  • Direct Boot. Enabled by file-based encryption, Direct Boot allows certain apps such as alarm clock and accessibility features to run when device is powered on but not unlocked.
  • Verified Boot. Verified Boot is now strictly enforced to prevent compromised devices from booting; it supports error correction to improve reliability against non-malicious data corruption.
  • SELinux. Updated SELinux configuration and increased seccomp coverage further locks down the Application Sandbox and reduces attack surface.
  • Library load-order randomization and improved ASLR. Increased randomness makes some code-reuse attacks less reliable.
  • Kernel hardening. Added additional memory protection for newer kernels by marking portions of kernel memory as read-only, restricting kernel access to userspace addresses and further reducing the existing attack surface.
  • APK signature scheme v2. Introduced a whole-file signature scheme that improves verification speed and strengthens integrity guarantees.
  • Trusted CA store. To make it easier for apps to control access to their secure network traffic, user-installed certificate authorities and those installed through Device Admin APIs are no longer trusted by default for apps targeting API Level 24+. Additionally, all new Android devices must ship with the same trusted CA store.
  • Network Security Config. Configure network security and TLS through a declarative configuration file.

Android 6

Todas las versiones de Android incluyen docenas de mejoras de seguridad para proteger a los usuarios. Estas son algunas de las principales mejoras de seguridad disponibles en Android 6.0:

  • Permisos de tiempo de ejecución. Las apps solicitan permisos durante el tiempo de ejecución en lugar de que se les otorguen en el momento de la instalación. Los usuarios pueden activar o desactivar los permisos de las apps para M y anteriores.
  • Inicio verificado. Antes de la ejecución, se realiza un conjunto de verificaciones criptográficas del software del sistema para garantizar que el teléfono esté en buen estado desde el bootloader hasta el sistema operativo.
  • Seguridad aislada por hardware. Nueva capa de abstracción de hardware (HAL) que usan la API de huellas dactilares, la pantalla de bloqueo, la encriptación del dispositivo y los certificados de cliente para proteger las claves contra ataques físicos locales o de vulneración del kernel
  • Huellas dactilares: Ahora los dispositivos se pueden desbloquear con un solo toque. Los desarrolladores también pueden aprovechar las nuevas APIs para usar huellas dactilares para bloquear y desbloquear claves de encriptación.
  • Adopción de tarjetas SD. El contenido multimedia extraíble se puede adoptar en un dispositivo y expandir el almacenamiento disponible para los datos locales de la app, las fotos, los videos, etcétera, pero aún puede estar protegido por encriptación a nivel de bloque.
  • Tráfico de texto simple. Los desarrolladores pueden usar un nuevo StrictMode para asegurarse de que su app no use texto simple.
  • Endurecimiento del sistema. Endurecimiento del sistema a través de políticas que aplica SELinux Esto ofrece un mejor aislamiento entre los usuarios, un filtrado de IOCTL, una reducción de la amenaza de los servicios expuestos, un mayor endurecimiento de los dominios de SELinux y un acceso extremadamente limitado a /proc.
  • Control de acceso USB: Los usuarios deben confirmar que permiten el acceso USB a los archivos, el almacenamiento y otras funciones del teléfono. La opción predeterminada ahora es solo cobro, con acceso al almacenamiento que requiere la aprobación explícita del usuario.

Android 5

5.0

Todas las versiones de Android incluyen docenas de mejoras de seguridad para proteger a los usuarios. Estas son algunas de las principales mejoras de seguridad disponibles en Android 5.0:

  • Están encriptados de forma predeterminada. En los dispositivos que se envían con L preinstalada, la encriptación completa del disco está habilitada de forma predeterminada para mejorar la protección de los datos en dispositivos perdidos o robados. Los dispositivos que se actualizan a L se pueden encriptar en Configuración > Seguridad .
  • Se mejoró la encriptación de disco completo. La contraseña del usuario está protegida contra ataques de descifrado por fuerza bruta con scrypt y, cuando está disponible, la clave está vinculada al almacén de claves de hardware para evitar ataques fuera del dispositivo. Como siempre, el secreto del bloqueo de pantalla de Android y la clave de encriptación del dispositivo no se envían fuera del dispositivo ni se exponen a ninguna aplicación.
  • Zona de pruebas de Android reforzada con SELinux . Ahora Android requiere SELinux en modo de aplicación forzosa para todos los dominios. SELinux es un sistema de control de acceso obligatorio (MAC) en el kernel de Linux que se usa para aumentar el modelo de seguridad de control de acceso discrecional (DAC) existente. Esta nueva capa proporciona protección adicional contra posibles vulnerabilidades de seguridad.
  • Smart Lock. Android ahora incluye trustlets que proporcionan más flexibilidad para desbloquear dispositivos. Por ejemplo, los trustlets pueden permitir que los dispositivos se desbloqueen automáticamente cuando están cerca de otro dispositivo de confianza (a través de NFC o Bluetooth) o cuando los usa alguien con un rostro de confianza.
  • Modos multiusuario, de perfil restringido y de invitado para teléfonos y tablets Android ahora admite varios usuarios en teléfonos y incluye un modo invitado que se puede usar para proporcionar acceso temporal y sencillo a tu dispositivo sin otorgar acceso a tus datos y apps.
  • Actualizaciones de WebView sin OTA WebView ahora se puede actualizar independientemente del framework y sin un sistema OTA. Esto permite una respuesta más rápida a posibles problemas de seguridad en WebView.
  • Se actualizó la criptografía para HTTPS y TLS/SSL. Ahora se habilitaron TLSv1.2 y TLSv1.1, se prefiere la confidencialidad directa, se habilitó AES-GCM y se inhabilitaron los conjuntos de algoritmos de cifrado débiles (MD5, 3DES y conjuntos de algoritmos de cifrado de exportación). Consulta https://developer.android.com/reference/javax/net/ssl/SSLSocket.html para obtener más detalles.
  • Se quitó la compatibilidad con el vinculador no PIE. Android ahora requiere que todos los ejecutables vinculados de forma dinámica admitan PIE (ejecutables independientes de la posición). Esto mejora la implementación de la aleatorización del diseño del espacio de direcciones (ASLR) de Android.
  • Mejoras en FORTIFY_SOURCE. Las siguientes funciones de libc ahora implementan protecciones FORTIFY_SOURCE: stpcpy(), stpncpy(), read(), recvfrom(), FD_CLR(), FD_SET() y FD_ISSET(). Esto proporciona protección contra vulnerabilidades de corrupción de memoria que involucran esas funciones.
  • Correcciones de seguridad. Android 5.0 también incluye correcciones para vulnerabilidades específicas de Android. Los miembros de Open Handset Alliance recibieron información acerca de estas vulnerabilidades y las correcciones están disponibles en el Proyecto de código abierto de Android. Para mejorar la seguridad, es posible que algunos dispositivos con versiones anteriores de Android también incluyan estas correcciones.

Android 4 y versiones anteriores

Todas las versiones de Android incluyen docenas de mejoras de seguridad para proteger a los usuarios. A continuación, se muestran algunas de las mejoras de seguridad disponibles en Android 4.4:

  • La zona de pruebas de Android se reforzó con SELinux. Android ahora usa SELinux en modo de aplicación forzosa. SELinux es un sistema de control de acceso obligatorio (MAC) en el kernel de Linux que se usa para aumentar el modelo de seguridad existente basado en el control de acceso discrecional (DAC). Esto proporciona protección adicional contra posibles vulnerabilidades de seguridad.
  • VPN por usuario En los dispositivos para varios usuarios, las VPN ahora se aplican por usuario. Esto puede permitir que un usuario enrute todo el tráfico de red a través de una VPN sin afectar a otros usuarios del dispositivo.
  • Compatibilidad con el proveedor de ECDSA en AndroidKeyStore. Android ahora tiene un proveedor de almacén de claves que permite el uso de algoritmos ECDSA y DSA.
  • Advertencias de supervisión de dispositivos. Android les proporciona a los usuarios una advertencia si se agregó un certificado al almacén de certificados del dispositivo que podría permitir la supervisión del tráfico de red encriptado.
  • FORTIFY_SOURCE. Android ahora admite el nivel 2 de FORTIFY_SOURCE, y todo el código se compila con estas protecciones. Se mejoró FORTIFY_SOURCE para que funcione con clang.
  • Fijación de certificados: Android 4.4 detecta y evita el uso de certificados fraudulentos de Google que se usan en comunicaciones SSL/TLS seguras.
  • Correcciones de seguridad. Android 4.4 también incluye correcciones para vulnerabilidades específicas de Android. Los miembros de Open Handset Alliance recibieron información acerca de estas vulnerabilidades y las correcciones están disponibles en el Proyecto de código abierto de Android. Para mejorar la seguridad, es posible que algunos dispositivos con versiones anteriores de Android también incluyan estas correcciones.

Every Android release includes dozens of security enhancements to protect users. The following are some of the security enhancements available in Android 4.3:

  • Android sandbox reinforced with SELinux. This release strengthens the Android sandbox using the SELinux mandatory access control system (MAC) in the Linux kernel. SELinux reinforcement is invisible to users and developers, and adds robustness to the existing Android security model while maintaining compatibility with existing apps. To ensure continued compatibility this release allows the use of SELinux in a permissive mode. This mode logs any policy violations, but will not break apps or affect system behavior.
  • No setuid or setgid programs. Added support for filesystem capabilities to Android system files and removed all setuid or setgid programs. This reduces root attack surface and the likelihood of potential security vulnerabilities.
  • ADB authentication. Starting in Android 4.2.2, connections to ADB are authenticated with an RSA keypair. This prevents unauthorized use of ADB where the attacker has physical access to a device.
  • Restrict Setuid from Android Apps. The /system partition is now mounted nosuid for zygote-spawned processes, preventing Android apps from executing setuid programs. This reduces root attack surface and the likelihood of potential security vulnerabilities.
  • Capability bounding. Android zygote and ADB now use prctl(PR_CAPBSET_DROP) to drop unnecessary capabilities prior to executing apps. This prevents Android apps and apps launched from the shell from acquiring privileged capabilities.
  • AndroidKeyStore Provider. Android now has a keystore provider that allows apps to create exclusive use keys. This provides apps with an API to create or store private keys that cannot be used by other apps.
  • KeyChain isBoundKeyAlgorithm. Keychain API now provides a method (isBoundKeyType) that allows apps to confirm that system-wide keys are bound to a hardware root of trust for the device. This provides a place to create or store private keys that can't be exported off the device, even in the event of a root compromise.
  • NO_NEW_PRIVS. Android zygote now uses prctl(PR_SET_NO_NEW_PRIVS) to block addition of new privileges prior to execution app code. This prevents Android apps from performing operations that can elevate privileges through execve. (This requires Linux kernel version 3.5 or greater).
  • FORTIFY_SOURCE enhancements. Enabled FORTIFY_SOURCE on Android x86 and MIPS and fortified strchr(), strrchr(), strlen(), and umask() calls. This can detect potential memory corruption vulnerabilities or unterminated string constants.
  • Relocation protections. Enabled read only relocations (relro) for statically linked executables and removed all text relocations in Android code. This provides defense in depth against potential memory corruption vulnerabilities.
  • Improved EntropyMixer. EntropyMixer now writes entropy at shutdown or reboot, in addition to periodic mixing. This allows retention of all entropy generated while devices are powered on, and is especially useful for devices that are rebooted immediately after provisioning.
  • Security fixes. Android 4.3 also includes fixes for Android-specific vulnerabilities. Information about these vulnerabilities has been provided to Open Handset Alliance members and fixes are available in Android Open Source Project. To improve security, some devices with earlier versions of Android may also include these fixes.

Android provides a multi-layered security model described in the Android Security Overview. Each update to Android includes dozens of security enhancements to protect users. The following are some of the security enhancements introduced in Android 4.2:

  • App verification: Users can choose to enable Verify Apps and have apps screened by an app verifier, prior to installation. App verification can alert the user if they try to install an app that might be harmful; if an app is especially bad, it can block installation.
  • More control of premium SMS: Android provides a notification if an app attempts to send SMS to a short code that uses premium services that might cause additional charges. The user can choose whether to allow the app to send the message or block it.
  • Always-on VPN: VPN can be configured so that apps won't have access to the network until a VPN connection is established. This prevents apps from sending data across other networks.
  • Certificate pinning: The Android core libraries now support certificate pinning. Pinned domains receive a certificate validation failure if the certificate doesn't chain to a set of expected certificates. This protects against possible compromise of certificate authorities.
  • Improved display of Android permissions: Permissions are organized into groups that are more easily understood by users. During review of the permissions, the user can click on the permission to see more detailed information about the permission.
  • installd hardening: The installd daemon does not run as the root user, reducing potential attack surface for root privilege escalation.
  • init script hardening: init scripts now apply O_NOFOLLOW semantics to prevent symlink related attacks.
  • FORTIFY_SOURCE: Android now implements FORTIFY_SOURCE. This is used by system libraries and apps to prevent memory corruption.
  • ContentProvider default configuration: Apps that target API level 17 have export set to false by default for each Content Provider, reducing default attack surface for apps.
  • Cryptography: Modified the default implementations of SecureRandom and Cipher.RSA to use OpenSSL. Added SSL Socket support for TLSv1.1 and TLSv1.2 using OpenSSL 1.0.1
  • Security fixes: Upgraded open source libraries with security fixes include WebKit, libpng, OpenSSL, and LibXML. Android 4.2 also includes fixes for Android-specific vulnerabilities. Information about these vulnerabilities has been provided to Open Handset Alliance members and fixes are available in Android Open Source Project. To improve security, some devices with earlier versions of Android may also include these fixes.

Android provides a multi-layered security model described in the Android Security Overview. Each update to Android includes dozens of security enhancements to protect users. The following are some of the security enhancements introduced in Android versions 1.5 through 4.1:

Android 1.5
  • ProPolice to prevent stack buffer overruns (-fstack-protector)
  • safe_iop to reduce integer overflows
  • Extensions to OpenBSD dlmalloc to prevent double free() vulnerabilities and to prevent chunk consolidation attacks. Chunk consolidation attacks are a common way to exploit heap corruption.
  • OpenBSD calloc to prevent integer overflows during memory allocation
Android 2.3
  • Format string vulnerability protections (-Wformat-security -Werror=format-security)
  • Hardware-based No eXecute (NX) to prevent code execution on the stack and heap
  • Linux mmap_min_addr to mitigate null pointer dereference privilege escalation (further enhanced in Android 4.1)
Android 4.0
Address Space Layout Randomization (ASLR) to randomize key locations in memory
Android 4.1
  • PIE (Position Independent Executable) support
  • Read-only relocations / immediate binding (-Wl,-z,relro -Wl,-z,now)
  • dmesg_restrict enabled (avoid leaking kernel addresses)
  • kptr_restrict enabled (avoid leaking kernel addresses)