Malware and Mobile unwanted software (MUwS)

Our Malware policy is simple, the Android ecosystem including the Google Play Store, and user devices should be free from malicious behaviors (for example, malware). Through this fundamental principle we strive to provide a safe Android ecosystem for our users and their Android devices.

Malware is any code that could put a user, a user's data, or a device at risk. Malware includes, but is not limited to, Potentially Harmful Applications (PHAs), binaries, or framework modifications, consisting of categories such as trojans, phishing, and spyware apps, and we are continuously updating and adding new categories.

Though varied in type and capabilities, malware usually has one of the following objectives:

  • Compromise the integrity of the user's device.
  • Gain control over a user's device.
  • Enable remote-controlled operations for an attacker to access, use, or otherwise exploit an infected device.
  • Transmit personal data or credentials off the device without adequate disclosure and consent.
  • Disseminate spam or commands from the infected device to affect other devices or networks.
  • Defraud the user.

An app, binary, or framework modification can be potentially harmful, and therefore can generate malicious behavior, even if it wasn't intended to be harmful. This is because apps, binaries, or framework modifications can function differently depending on a variety of variables. Therefore, what is harmful to one Android device might not pose a risk at all to another Android device. For example, a device running the latest version of Android is not affected by harmful apps which use deprecated APIs to perform malicious behavior but a device that is still running a very early version of Android might be at risk. Apps, binaries, or framework modifications are flagged as malware or PHA if they clearly pose a risk to some or all Android devices and users.

The malware categories below, reflect our foundational belief that users should understand how their device is being leveraged and promote a secure ecosystem that enables robust innovation and a trusted user experience.

Malware categories

Backdoor

Backdoor

Code that allows the execution of unwanted, potentially harmful, remote-controlled operations on a device.

These operations may include behavior that would place the app, binary, or framework modification into one of the other malware categories if executed automatically. In general, backdoor is a description of how a potentially harmful operation can occur on a device and is therefore not completely aligned with categories like billing fraud or commercial spyware. As a result, a subset of backdoors, under some circumstances, are treated by Google Play Protect as a vulnerability.

Billing fraud

Billing fraud

Code that automatically charges the user in an intentionally deceptive way.

Mobile billing fraud is divided into SMS fraud, Call fraud, and Toll fraud.

SMS fraud

Code that charges users to send premium SMS without consent, or tries to disguise its SMS activities by hiding disclosure agreements or SMS messages from the mobile operator notifying the user of charges or confirming subscriptions.

Some code, even though they technically disclose SMS sending behavior, introduce additional behavior that accommodates SMS fraud. Examples include hiding parts of a disclosure agreement from the user, making them unreadable, and conditionally suppressing SMS messages from the mobile operator informing the user of charges or confirming a subscription.

Call fraud

Code that charges users by making calls to premium numbers without user consent.

Toll fraud

Code that tricks users into subscribing to or purchasing content via their mobile phone bill.

Toll Fraud includes any type of billing except premium SMS and premium calls. Examples of this include direct carrier billing, wireless access point (WAP), and mobile airtime transfer. WAP fraud is one of the most prevalent types of Toll fraud. WAP fraud can include tricking users to click a button on a silently loaded, transparent WebView. Upon performing the action, a recurring subscription is initiated, and the confirmation SMS or email is often hijacked to prevent users from noticing the financial transaction.

Commercial spyware

Commercial spyware

Code that transmits personal information off the device without adequate notice or consent and doesn't display a persistent notification that this is happening.

Commercial spyware apps transmit data to a party other than the PHA provider. Legitimate forms of these apps can be used by parents to track their children. However, these apps can not be used to track a person (a spouse, for example) without their knowledge or permission if a persistent notification is not displayed while the data is being transmitted.

Denial of service

Denial of service (DoS)

Code that, without the knowledge of the user, executes a denial-of-service (DoS) attack or is a part of a distributed DoS attack against other systems and resources.

For example, this can happen by sending a high volume of HTTP requests to produce excessive load on remote servers.

Hostile downloaders

Hostile downloaders

Code that isn't in itself potentially harmful, but downloads other PHAs.

Code may be a hostile downloader if:

  • There is reason to believe it was created to spread PHAs and it has downloaded PHAs or contains code that could download and install apps; or
  • At least 5% of apps downloaded by it are PHAs with a minimum threshold of 500 observed app downloads (25 observed PHA downloads).

Major browsers and file-sharing apps aren't considered hostile downloaders as long as:

  • They don't drive downloads without user interaction; and
  • All PHA downloads are initiated by consenting users.
Non-Android threat

Non-Android threat

Code that contains non-Android threats.

These apps can't cause harm to the Android user or device, but contain components that are potentially harmful to other platforms.

Phishing

Phishing

Code that pretends to come from a trustworthy source, requests a user's authentication credentials or billing information, and sends the data to a third-party. This category also applies to code that intercept the transmission of user credentials in transit.

Common targets of phishing include banking credentials, credit card numbers, and online account credentials for social networks and games.

Privilege escalation

Elevated privilege abuse

Code that compromises the integrity of the system by breaking the app sandbox, gaining elevated privileges, or changing or disabling access to core security-related functions.

Examples include:

  • An app that violates the Android permissions model, or steals credentials (such as OAuth tokens) from other apps.
  • Apps that abuse features to prevent them from being uninstalled or stopped.
  • An app that disables SELinux.

Privilege escalation apps that root devices without user permission are classified as rooting apps.

Ransomware

Ransomware

Code that takes partial or extensive control of a device or data on a device and demands that the user make a payment or perform an action to release control.

Some ransomware encrypts data on the device and demands payment to decrypt the data and/or leverage the device admin features so that it can't be removed by a typical user. Examples include:

  • Locking a user out of their device and demanding money to restore user control.
  • Encrypting data on the device and demanding payment, ostensibly to decrypt the data.
  • Leveraging device policy manager features and blocking removal by the user.

Code distributed with the device whose primary purpose is for subsidized device management may be excluded from the ransomware category provided they successfully meet requirements for secure lock and management, and adequate user disclosure and consent requirements.

Rooting

Rooting

Code that roots the device.

There's a difference between non-malicious and malicious rooting code. For example, rooting apps let the user know in advance that they're going to root the device and they don't execute other potentially harmful actions that apply to other PHA categories.

Malicious rooting apps don't inform the user that they're going to root the device, or they inform the user about the rooting in advance but also execute other actions that apply to other PHA categories.

Spam

Spam

Code that sends unsolicited messages to the user's contacts or uses the device as an email spam relay.


Rooting

Spyware

Code that transmits personal data off the device without adequate notice or consent.

For example, transmitting any of the following information without disclosures or in a manner that is unexpected to the user is sufficient to be considered spyware:

  • Contact list
  • Photos or other files from the SD card or that aren't owned by the app
  • Content from user email
  • Call log
  • SMS log
  • Web history or browser bookmarks of the default browser
  • Information from the /data/ directories of other apps.

Behaviors that can be considered as spying on the user can also be flagged as spyware. For example, recording audio or recording calls made to the phone, or stealing app data.

Trojan

Trojan

Code that appears to be benign, such as a game that claims only to be a game, but that performs undesirable actions against the user.

This classification is usually used in combination with other PHA categories. A trojan has an innocuous component and a hidden harmful component. For example, a game that sends premium SMS messages from the user's device in the background and without the user's knowledge.

Uncommon

Uncommon

New and rare apps can be classified as uncommon if Google Play Protect doesn't have enough information to clear them as safe. This doesn't mean the app is necessarily harmful, but without further review it can't be cleared as safe either.

Mobile unwanted software (MUwS)

Google defines unwanted software (UwS) as apps that aren’t strictly malware, but are harmful to the software ecosystem. Mobile unwanted software (MUwS) impersonates other apps or collects at least one of the following without user consent:

  • Device phone number
  • Primary email address
  • Information about installed apps
  • Information about third-party accounts

MUwS is tracked separately from Malware categories. The section below describes the different categories of MUwS.

Mobile Unwanted Software (MUwS) categories

Click fraud

Click fraud

An app that automatically generates clicks on ads without the user's intervention or that produces equivalent network traffic to fraudulently give click credits.

These apps can result in the app developer profiting from fake ad clicks or fake click traffic that defraud the advertisers and ad networks.

Data collection

Data collection

An app that collects and transmits personal data without adequate notice or consent. This may include collecting the list of installed apps, the device phone number, email addresses or other third-party account IDs, or other personal information.

Impersonation

Impersonation

An app that pretends to be another app with the intention of deceiving users into performing actions that the user intended for the original trusted app.


Disruptive ads

Disruptive ads

An app that shows ads that are displayed to users in unexpected ways including impairing or interfering with the usability of device functions, or displaying outside the triggering app’s environment without adequate consent and attribution.

Google Play Protect Warnings

When Google Play Protect detects a violation of the malware policy, a warning will display for the user. Warning strings for each violation are available here.