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:
- Application verification - Users can choose to enable “Verify Apps" and have applications screened by an application verifier, prior to installation. App verification can alert the user if they try to install an app that might be harmful; if an application is especially bad, it can block installation.
- More control of premium SMS - Android will provide a notification if an application attempts to send SMS to a short code that uses premium services which might cause additional charges. The user can choose whether to allow the application to send the message or block it.
- Always-on VPN - VPN can be configured so that applications will not have access to the network until a VPN connection is established. This prevents applications from sending data across other networks.
- Certificate Pinning - The Android core libraries now support certificate pinning. Pinned domains will receive a certificate validation failure if the certificate does not chain to a set of expected certificates. This protects against possible compromise of Certificate Authorities.
- Improved display of Android permissions - Permissions have been 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
installddaemon does not run as the root user, reducing potential attack surface for root privilege escalation.
- init script hardening - init scripts now apply
O_NOFOLLOWsemantics to prevent symlink related attacks.
- FORTIFY_SOURCE - Android now implements
FORTIFY_SOURCE. This is used by system libraries and applications to prevent memory corruption.
- ContentProvider default configuration - Applications which target API level 17 will have "export" set to "false" by default for each Content Provider, reducing default attack surface for applications.
- 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.