The Android Debug Bridge (commonly abbreviated as adb) is a

programming tool A programming tool or software development tool is a computer program that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs, that can b ...

used for the debugging of Android-based devices. The

daemon Daimon or Daemon (Ancient Greek: , "god", "godlike", "power", "fate") originally referred to a lesser deity or guiding spirit such as the daimons of ancient Greek religion and Greek mythology, mythology and of later Hellenistic religion and Hell ...

on the Android device connects with the server on the host PC over

USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...

or TCP, which connects to the client that is used by the end-user over TCP. Made available as

open-source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Op ...

under the Apache License by

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

since 2007, features include a shell and the possibility to make backups. The adb software is compatible with

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ser ...

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, w ...

and

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...

. It has been misused by

botnet A botnet is a group of Internet-connected devices, each of which runs one or more bots. Botnets can be used to perform Distributed Denial-of-Service (DDoS) attacks, steal data, send spam, and allow the attacker to access the device and its conn ...

s and other

malicious software Malware (a portmanteau for ''malicious software'') is any software intentionally designed to cause disruption to a computer, server, client, or computer network, leak private information, gain unauthorized access to information or systems, ...

, for which mitigations were developed such as RSA authentication and device

whitelisting A whitelist, allowlist, or passlist is a mechanism which explicitly allows some identified entities to access a particular privilege, service, mobility, or recognition i.e. it is a list of things allowed when everything is denied by default. It is ...

Features

Features of adb include copying files from the host computer, installing apps, viewing logcat output, getting a

Unix shell A Unix shell is a command-line interpreter or shell that provides a command line user interface for Unix-like operating systems. The shell is both an interactive command language and a scripting language, and is used by the operating syste ...

, and rebooting into Qualcomm EDL mode. For example, Android

applications Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...

can be saved by the command backup to a file. It also includes support for the

Java Debug Wire Protocol In computing, the Java Debug Wire Protocol (JDWP) is a communication protocol which is part of the Java Platform Debugger Architecture. It is used for communication between a debugger and the Java Virtual Machine, which it debugs. It allows to debu ...

. Some graphical interfaces have been made available. The graphical Android Device Monitor in

Android Studio Android Studio is the official integrated development environment (IDE) for Google's Android operating system, built on JetBrains' IntelliJ IDEA software and designed specifically for Android development. It is available for download on Windows ...

can be used for retrieving information from an Android device.

Development history

The Android Software Development Kit (SDK) was first released in 2007. Since 2017, Google made it possible to download adb separately from the Android SDK. In 2015, Microsoft released an Android emulator that can connect to the adb client. In 2016 for

2.0 a 5x performance improvement was made for installing apps and pushing files through adb. For easier usage of Android Things, a wrapper was made in 2017 around manual adb commands. For Android 11 in 2020, Google added adb incremental installations. In 2020, Wi-Fi adb was integrated into Android Studio for macOS. In 2021 for

Android 12 Android 12 is the twelfth major release and 19th version of Android, the mobile operating system developed by the Open Handset Alliance led by Google. The first beta was released on May 18, 2021. Android 12 was released publicly on October 4 ...

, the adb backup command was limited so that backing up user data from apps is opt-in using a per-app manifesto configuration.

Fuchsia ''Fuchsia'' () is a genus of flowering plants that consists mostly of shrubs or small trees. The first to be scientifically described, ''Fuchsia triphylla'', was discovered on the Caribbean island of Hispaniola (Haiti and the Dominican Republic) ...

will be backwards-compatible with adb. It will be replaced with fx and ffx.

Setup

Host computer

For Windows, the Android SDK contains the adb.exe binary that can be extracted and installed. How-To Geek recommends adding the folder containing the binaries to the

PATH A path is a route for physical travel – see Trail. Path or PATH may also refer to: Physical paths of different types * Bicycle path * Bridle path, used by people on horseback * Course (navigation), the intended path of a vehicle * Desire p ...

environment variable. On

Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: '' Desktop'', ''Server'', and ''Core'' for Internet of things devices and robots. All ...

, adb can be installed with the android-tools-adb package. For Debian, it has been recommended to also install the android-sdk-platform-tools-common package next to the adb package, which installs the

udev udev (userspace ) is a device manager for the Linux kernel. As the successor of devfsd and hotplug, udev primarily manages device nodes in the directory. At the same time, udev also handles all user space events raised when hardware devices ...

rules which makes it possible to run the tool without root permissions. For macOS and other Linux distributions, the platform tools can be downloaded and the PATH variable can be modified in bashrc.

Android device

In Android 4.2.2 or later ( API level 17), a dialog is shown with an RSA

fingerprint A fingerprint is an impression left by the friction ridges of a human finger. The recovery of partial fingerprints from a crime scene is an important method of forensic science. Moisture and grease on a finger result in fingerprints on surfac ...

that the user needs to accept. This protects against computers exploiting the debugging mechanism without consent of the device user. Starting in Android 4.2, the developer settings are hidden by default. Pressing seven times on the build number in the about menu makes them visible to the user. After that, the USB debugging option can be enabled. Some Android vendors have different procedures to enable it. For example, Huawei requires entering a pincode before adb can be enabled. If the

touchscreen A touchscreen or touch screen is the assembly of both an input ('touch panel') and output ('display') device. The touch panel is normally layered on the top of an electronic visual display of an information processing system. The display is ofte ...

of an Android device is broken, it can be possible to connect a mouse to the device using

USB On-The-Go USB On-The-Go (USB OTG or just OTG) is a specification first used in late 2001 that allows USB devices, such as tablets or smartphones, to act as a host, allowing other USB devices, such as USB flash drives, digital cameras, mouse or keybo ...

and enable USB debugging.

Architecture

The adb protocol can be transported over USB or over

Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wav ...

through TCP. It uses a client-server architecture. There are two different protocols in use. The first is between the client and the server and the second is between the server and the daemon. The adb daemon is implemented in C and located in the Android user space. The daemon is facilitated by the Android USB framework, UsbDeviceManager and UsbDebuggingManager.

Client ↔ server protocol

The communication mode between the client and server is a TCP socket. The server listens on a port, to which the client has to send a request. The request contains a 4-byte initial field in ASCII and a payload. The payload starts with the word host, to indicate it should be sent to the server. The server can then reply with OKAY or FAIL to indicate the status, combined with an optional payload and length.

Server ↔ daemon protocol

The messages sent from the server consist of a 24-byte long header, with the following fields: * Command * First argument * Second argument * Length of the payload, 0 or higher * CRC32 of the data payload * Magic value, calculated through command XOR 0xFFFFFFFF

Security

Up to

Android 2.2 Android Froyo is the sixth version of Android and is a codename of the Android mobile operating system developed by Google, spanning versions between 2.2 and 2.2.3. Those versions are no longer supported. It was unveiled on May 20, 2010, duri ...

, Android was vulnerable to the ''RageAgainstTheCage''

exploit Exploit means to take advantage of something (a person, situation, etc.) for one's own end, especially unethically or unjustifiably. Exploit can mean: *Exploitation of natural resources *Exploit (computer security) * Video game exploit *Exploitat ...

. The adb

did not check for the return value of the

setuid The Unix access rights flags setuid and setgid (short for ''set user identity'' and ''set group identity'') allow users to run an executable with the file system permissions of the executable's owner or group respectively and to change behaviour ...

system call In computing, a system call (commonly abbreviated to syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, acc ...

when dropping privileges. The exploit forks processes until it fails due to the exhaustion of

process identifier In computing, the process identifier (a.k.a. process ID or PID) is a number used by most operating system kernels—such as those of Unix, macOS and Windows—to uniquely identify an active process. This number may be used as a parameter in vario ...

s. When the daemon crashes and restarts, it cannot start a new process with dropped privileges and keeps running as root. Then adb provided a root shell. In 2017, a security vulnerability was disclosed that exploited ADB to take over the onboard

modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...

. The attack required adb to be already enabled and authorized, although some workarounds were available. Various families of malware such as ADB.Miner, Ares, IPStorm, Fbot and Trinity have scanned the internet for public availability of the adb interface and installed malware on those devices. adb can also be used to remove malware, by booting into safe mode and running the adb uninstall command.

References

External links

Android Debug Bridge - Android Developers

LineageOS
Android Debug Bridge

Arch Linux Arch Linux () is an independently developed, x86-64 general-purpose Linux distribution that strives to provide the latest stable versions of most software by following a rolling-release model. The default installation is a minimal base system, ...

wiki * adb, Gentoo Linux wiki
Android Debug Bridge, Droid Wiki
{{Android Android (operating system) Debugging Communications protocols Android (operating system) development software