Android 一直在不断改进其安全功能和产品/服务。您可以在左侧导航栏中查看各个版本的增强功能列表。
Android 14
每个 Android 版本中都包含数十种安全增强功能,以保护用户。以下是 Android 14 中提供的一些主要安全增强功能:
- Android 10 中引入的硬件辅助 AddressSanitizer (HWASan) 是一款类似于 AddressSanitizer 的内存错误检测工具。Android 14 对 HWASan 进行了重大改进。如需了解它如何帮助防止 bug 进入 Android 版本,请访问 HWAddressSanitizer
- 在 Android 14 中,从与第三方共享位置数据的应用开始,系统运行时权限对话框现在包含一个可点击的部分,用于突出显示应用的数据分享做法,包括诸如以下信息:应用为什么可能会决定与第三方分享数据。
- Android 12 引入了在调制解调器级别停用 2G 支持的选项,以保护用户免受 2G 的过时安全模型固有的安全风险的影响。认识到停用 2G 对企业客户的重要性后,Android 14 在 Android Enterprise 中启用了此安全功能,以便 IT 管理员能够限制受管设备降级到 2G 连接。
- 开始支持拒绝未加密的移动网络连接,确保电路交换语音和短信流量始终会加密,并可防范被动无线拦截。详细了解 Android 的移动网络连接强化计划。
- 新增了对多个 IMEI 的支持
- 从 Android 14 开始,AES-HCTR2 是采用加速加密指令的设备的首选文件名加密模式。
- 移动网络连接
- 在 Android 安全中心添加了相关文档
- 如果您的应用以 Android 14 为目标平台并使用动态代码加载 (DCL) 功能,则必须将所有动态加载的文件标记为只读。否则,系统会抛出异常。我们建议应用尽可能避免动态加载代码,因为这样做会大大增加应用因代码注入或代码篡改而遭到入侵的风险。
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
Every Android release includes dozens of security enhancements to protect users. Here are some of the major security enhancements available in Android 12:
- Android 12 introduces the BiometricManager.Strings API, which provides localized strings for apps that use BiometricPrompt for authentication. These strings are intended to be device-aware and provide more specificity about which authentication types might be used. Android 12 also includes support for under-display fingerprint sensors
- Support added for under-display fingerprint sensors
- Introduction of the Fingerprint Android Interface Definition Language (AIDL)
- Support for new Face AIDL
- Introduction of Rust as a language for platform development
- The option for users to grant access only to their approximate location added
- Added Privacy indicators on the status bar when an app is using the camera or microphone
- Android's Private Compute Core (PCC)
- Added an option to disable 2G support
Android 11
Every Android release includes dozens of security enhancements to protect users. For a list of some of the major security enhancements available in Android 11, see the Android Release Notes.
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:
- Android Runtime
- Conscrypt
- DNS Resolver
- DocumentsUI
- ExtServices
- Media
- ModuleMetadata
- Networking
- PermissionController
- Time Zone Data
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 eitherACCESS_FINE_LOCATION
orACCESS_COARSE_LOCATION
, the system automatically adds a<uses-permission>
element forACCESS_BACKGROUND_LOCATION
during installation. - If your app requests either
ACCESS_FINE_LOCATION
orACCESS_COARSE_LOCATION
, the system automatically addsACCESS_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'stargetSdkVersion
orcompileSdkVersion
to29
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:
- Files in the app-specific directory, accessed using
getExternalFilesDir()
. - Photos, videos, and audio clips that the app created from the media store.
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.
Build
TelephonyManager
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 theREAD_PHONE_STATE
permission. Otherwise, aSecurityException
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:
- The
getConfiguredNetworks()
method always returns an empty list. - Each network operation method that returns an integer value—
addNetwork()
andupdateNetwork()
—always returns -1. - Each network operation that returns a boolean value—
removeNetwork()
,reassociate()
,enableNetwork()
,disableNetwork()
,reconnect()
, anddisconnect()
—always returnsfalse
.
Android 9
Every Android release includes dozens of security enhancements to protect users. For a list of some of the major security enhancements available in Android 9, see the Android Release Notes.
Android 8
每个 Android 版本中都包含数十种用于保护用户的安全增强功能。以下是 Android 8.0 中提供的一些主要安全增强功能:
- 加密:在工作资料中增加了对撤销密钥 (evict key) 的支持。
- 验证启动:增加了 Android 启动时验证 (AVB)。支持回滚保护(用于引导加载程序)的启动时验证代码库已添加到 AOSP 中。建议提供引导加载程序支持,以便为 HLOS 提供回滚保护。建议将引导加载程序设为只能由用户通过实际操作设备来解锁。
- 锁定屏幕:增加了对使用防篡改硬件验证锁定屏幕凭据的支持。
- KeyStore:搭载 Android 8.0 及更高版本的所有设备都需要进行密钥认证。增加了 ID 认证支持,以改进零触摸注册计划。
- 沙盒:使用 Treble 计划的框架和设备特定组件之间的标准接口更紧密地对许多组件进行沙盒化处理。将 seccomp 过滤应用到了所有不信任的应用,以减少内核的攻击面。WebView 现在运行在一个独立的进程中,对系统其余部分的访问非常有限。
- 内核加固:实现了经过安全强化的 usercopy、PAN 模拟、初始化后变为只读以及 KASLR。
- 用户空间安全强化:为媒体堆栈实现了 CFI。 应用叠加层不能再遮盖系统关键窗口,并且用户可以关闭这些叠加层。
- 操作系统流式更新:在磁盘空间不足的设备上启用了更新。
- 安装未知应用:用户必须授予权限,系统才能从不是第一方应用商店的来源安装应用。
- 隐私权:对于设备上的每个应用和使用设备的每个用户,Android ID (SSAID) 都采用不同的值。对于网络浏览器应用,Widevine 客户端 ID 会针对每个应用软件包名称和网络来源返回不同的值。
net.hostname
现在为空,并且 DHCP 客户端不再发送主机名。android.os.Build.SERIAL
已被替换为Build.SERIAL
API(受到用户控制权限的保护)。改进了某些芯片组中的 MAC 地址随机分配功能。
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
每个 Android 版本中都包含数十种用于保护用户的安全增强功能。以下是 Android 6.0 中提供的一些主要安全增强功能:
- 运行时权限:应用在运行时请求权限,而不是在安装时被授予权限。用户可以为 M 及更低版本的 Android 应用启用和停用权限。
- 验证启动:在执行系统软件之前,先对其进行一系列加密检查,以确保手机从引导加载程序到操作系统均处于正常状况。
- 硬件隔离安全措施:新的硬件抽象层 (HAL),Fingerprint API、锁定屏幕、设备加密功能和客户端证书可以利用它来保护密钥免遭内核入侵和/或现场攻击。
- 指纹:现在,只需触摸一下,即可解锁设备。开发者还可以借助新的 API 来使用指纹锁定和解锁加密密钥。
- 加装 SD 卡:可将移动媒体设备加装到设备上,以便扩展可用存储空间来存放本地应用数据、照片、视频等内容,但仍受块级加密保护。
- 明文流量:开发者可以使用新的 StrictMode 来确保其应用不会使用明文。
- 系统加固:通过由 SELinux 强制执行的政策对系统进行加固。这可以实现更好的用户隔离和 IOCTL 过滤、降低可从设备/系统之外访问的服务面临的威胁、进一步强化 SELinux 域,以及高度限制对 /proc 的访问。
- USB 访问控制:必须由用户确认是否允许通过 USB 访问手机上的文件、存储空间或其他功能。现在,默认设置是“仅充电”,如果要访问存储空间,必须获得用户的明确许可。
Android 5
5.0
Every Android release includes dozens of security enhancements to protect users. Here are some of the major security enhancements available in Android 5.0:
- Encrypted by default. On devices that ship with L out-of-the-box, full disk encryption is enabled by default to improve protection of data on lost or stolen devices. Devices that update to L can be encrypted in Settings > Security .
- Improved full disk encryption. The user password is
protected against brute-force attacks using
scrypt
and, where available, the key is bound to the hardware keystore to prevent off-device attacks. As always, the Android screen lock secret and the device encryption key are not sent off the device or exposed to any application. - Android sandbox reinforced with SELinux . Android now requires SELinux in enforcing mode for all domains. SELinux is a mandatory access control (MAC) system in the Linux kernel used to augment the existing discretionary access control (DAC) security model. This new layer provides additional protection against potential security vulnerabilities.
- Smart Lock. Android now includes trustlets that provide more flexibility for unlocking devices. For example, trustlets can allow devices to be unlocked automatically when close to another trusted device (through NFC, Bluetooth) or being used by someone with a trusted face.
- Multi user, restricted profile, and guest modes for phones and tablets. Android now provides for multiple users on phones and includes a guest mode that can be used to provide easy temporary access to your device without granting access to your data and apps.
- Updates to WebView without OTA. WebView can now be updated independent of the framework and without a system OTA. This allows for faster response to potential security issues in WebView.
- Updated cryptography for HTTPS and TLS/SSL. TLSv1.2 and TLSv1.1 is now enabled, Forward Secrecy is now preferred, AES-GCM is now enabled, and weak cipher suites (MD5, 3DES, and export cipher suites) are now disabled. See https://developer.android.com/reference/javax/net/ssl/SSLSocket.html for more details.
- non-PIE linker support removed. Android now requires all dynamically linked executables to support PIE (position-independent executables). This enhances Android's address space layout randomization (ASLR) implementation.
- FORTIFY_SOURCE improvements. The following libc
functions now implement FORTIFY_SOURCE protections:
stpcpy()
,stpncpy()
,read()
,recvfrom()
,FD_CLR()
,FD_SET()
, andFD_ISSET()
. This provides protection against memory-corruption vulnerabilities involving those functions. - Security Fixes. Android 5.0 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 4 及更低版本
每个 Android 版本中都包含数十项用于保护用户的安全增强功能。以下是 Android 4.4 中提供的一些安全增强功能:
- 通过 SELinux 得到增强的 Android 沙盒。 Android 现在以强制模式使用 SELinux。SELinux 是 Linux 内核中的强制访问控制 (MAC) 系统,用于增强基于自主访问控制 (DAC) 的现有安全模型。 这为防范潜在的安全漏洞提供了额外的保护屏障。
- 按用户应用 VPN。 在多用户设备上,现在按用户应用 VPN。 这样一来,用户就可以通过一个 VPN 路由所有网络流量,而不会影响使用同一设备的其他用户。
- AndroidKeyStore 中的 ECDSA 提供程序支持。 Android 现在有一个允许使用 ECDSA 和 DSA 算法的密钥库提供程序。
- 设备监测警告。 如果有任何可能允许监测加密网络流量的证书添加到设备证书库中,Android 都会向用户发出警告。
- FORTIFY_SOURCE。 Android 现在支持 FORTIFY_SOURCE 第 2 级,并且所有代码在编译时都会受到这些保护。FORTIFY_SOURCE 已得到增强,能够与 Clang 配合使用。
- 证书锁定。 Android 4.4 能够检测安全的 SSL/TLS 通信中是否使用了欺诈性 Google 证书,并且能够阻止这种行为。
- 安全修复程序。 Android 4.4 中还包含针对 Android 特有漏洞的修复程序。 有关这些漏洞的信息已提供给“开放手机联盟”(Open Handset Alliance) 成员,并且 Android 开源项目中提供了相应的修复程序。为了提高安全性,搭载更低版本 Android 的某些设备可能也会包含这些修复程序。
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
orsetgid
programs. Added support for filesystem capabilities to Android system files and removed allsetuid
orsetgid
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 executingsetuid
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 usesprctl(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. EnabledFORTIFY_SOURCE
on Android x86 and MIPS and fortifiedstrchr()
,strrchr()
,strlen()
, andumask()
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 提供了一个多层安全模型,Android 安全性概述中对该模型进行了介绍。每个 Android 更新版本中都包含数十项用于保护用户的安全增强功能。 以下是 Android 4.2 中引入的一些安全增强功能:
- 应用验证:用户可以选择启用“验证应用”,并且可以选择在安装应用之前由应用验证程序对应用进行筛查。如果用户尝试安装的应用可能有害,应用验证功能可以提醒用户;如果应用的危害性非常大,应用验证功能可以阻止安装。
- 加强对付费短信的控制:如果有应用尝试向使用付费服务的短号码发送短信(可能会产生额外的费用),Android 将会通知用户。用户可以选择是允许还是阻止该应用发送短信。
- 始终开启的 VPN:可以配置 VPN,以确保在建立 VPN 连接之前应用无法访问网络。这有助于防止应用跨其他网络发送数据。
- 证书锁定:Android 的核心库现在支持证书锁定。如果证书未关联到一组应关联的证书,锁定的域将会收到证书验证失败消息。这有助于保护证书授权机构免遭可能的入侵。
- 改进后的 Android 权限显示方式:权限划分到了多个对用户来说更清晰明了的组中。在审核权限时,用户可以点击权限来查看关于相应权限的更多详细信息。
- installd 安全强化:
installd
守护程序不会以 root 用户身份运行,这样可以缩小 root 提权攻击的潜在攻击面。 - init 脚本安全强化:init 脚本现在会应用
O_NOFOLLOW
语义来防范与符号链接相关的攻击。 FORTIFY_SOURCE
:Android 现在会实现FORTIFY_SOURCE
,以供系统库和应用用于防范内存损坏。- ContentProvider 默认配置:默认情况下,对于每个 content provider,以 API 级别 17 为目标的应用都会将
export
设为false
,以缩小应用的默认受攻击面。 - 加密:修改了 SecureRandom 和 Cipher.RSA 的默认实现,以便使用 OpenSSL。为使用 OpenSSL 1.0.1 的 TLSv1.1 和 TLSv1.2 添加了安全套接字支持
- 安全漏洞修复程序:升级了开放源代码库,在其中新增了一些安全漏洞修复程序,其中包括 WebKit、libpng、OpenSSL 和 LibXML。Android 4.2 中还包含针对 Android 特有漏洞的修复程序。有关这些漏洞的信息已提供给“开放手机联盟”(Open Handset Alliance) 成员,并且 Android 开放源代码项目中提供了相应的修复程序。为了提高安全性,部分搭载更低版本 Android 系统的设备可能也会包含这些修复程序。
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)