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Input Capture
Adversaries may capture user input to obtain credentials or other information from the user through various methods.
Malware may masquerade as a legitimate third-party keyboard to record user keystrokes.[1] On both Android and iOS, users must explicitly authorize the use of third-party keyboard apps. Users should be advised to use extreme caution before granting this authorization when it is requested.
On Android, malware may abuse accessibility features to record keystrokes by registering an AccessibilityService class, overriding the onAccessibilityEvent method, and listening for the AccessibilityEvent.TYPE_VIEW_TEXT_CHANGED event type. The event object passed into the function will contain the data that the user typed.
Additional methods of keylogging may be possible if root access is available.
Procedure Examples
| Name | Description |
|---|---|
| Anubis |
Anubis has a keylogger that works in every application installed on the device.[2] |
| Cerberus | |
| EventBot |
EventBot can abuse Android’s accessibility service to record the screen PIN.[4] |
| FlexiSpy |
FlexiSpy can record keystrokes and analyze them for keywords.[5] |
| Gustuff |
Gustuff abuses accessibility features to intercept all interactions between a user and the device.[6] |
| Monokle |
Mitigations
| Mitigation | Description |
|---|---|
| Application Vetting |
Applications that attempt to register themselves as a device keyboard or request the |
| Enterprise Policy |
When using Samsung Knox, third-party keyboards must be explicitly added to an allow list in order to be available to the end-user.[8] |
| User Guidance |
Users should be weary of granting applications dangerous or privacy-intrusive permissions, such as keyboard registration and accessibility permissions requests. |
Detection
On Android, users can view and manage which applications have third-party keyboard access through the device settings in System -> Languages & input -> Virtual keyboard. On iOS, users can view and manage which applications have third-party keyboard access through the device settings in General -> Keyboard. On Android, users can view and manage which applications can use accessibility services through the device settings in Accessibility. The exact device settings menu locations may vary between operating system versions.
References
- Lenny Zeltser. (2016, July 30). Security of Third-Party Keyboard Apps on Mobile Devices. Retrieved December 21, 2016.
- M. Feller. (2020, February 5). Infostealer, Keylogger, and Ransomware in One: Anubis Targets More than 250 Android Applications. Retrieved April 8, 2020.
- Threat Fabric. (2019, August). Cerberus - A new banking Trojan from the underworld. Retrieved June 26, 2020.
- D. Frank, L. Rochberger, Y. Rimmer, A. Dahan. (2020, April 30). EventBot: A New Mobile Banking Trojan is Born. Retrieved June 26, 2020.
- FlexiSpy. (n.d.). FlexiSpy Monitoring Features. Retrieved September 4, 2019.
- Vitor Ventura. (2019, April 9). Gustuff banking botnet targets Australia . Retrieved September 3, 2019.
- Bauer A., Kumar A., Hebeisen C., et al. (2019, July). Monokle: The Mobile Surveillance Tooling of the Special Technology Center. Retrieved September 4, 2019.
- Samsung. (2019, August 16). 3rd party keyboards must be whitelisted.. Retrieved September 1, 2019.