Predictive Back / Recents Snapshot Leakage

← Improper Platform Usage

predictive_back_leakage   EASY

Description

Android 14+ predictive-back / recents snapshot captures a sensitive screen because it is not marked secure.

How it works

This sensitive screen is not marked secure, so Android 14+ captures its content into the recents (task-switcher) and predictive-back snapshot, retaining the secret where others can see it. Setting FLAG_SECURE or setRecentsScreenshotEnabled(false) would store an obscured placeholder instead. This button simulates the OS snapshot.

How to exercise it. DVMA is the harness - open this module from the home index and tap the demo action. The screen ships the malicious input and simulates the attacker (e.g. the companion app, crafted intent, or scanned payload) in-process, and the evidence panel prints the proof. The Tools (optional) and Attack inputs below are only needed to reproduce the exploit end-to-end on a real device.

Exploit steps

1. Set up. Build DVMA with a flavor that enables the Improper Platform Usage category (e.g. --dart-define-from-file=config/flavors/dev.json) and run on an Android emulator you control. The demo needs no external tooling; for the optional on-device reproduction the relevant tools are: adb shell screencap, scrcpy.
2. Locate the target. From the home index, open Predictive Back / Recents Snapshot Leakage (predictive_back_leakage). The How it works section above describes this module’s specific weakness; the screen states the intended-secure behavior and exposes the vulnerable action.
3. Exploit. From a co-resident/attacker context (adb shell am start/drozer, or a crafted deep link / QR), send the untrusted input to the exported component or WebView and confirm the app performs the unsafe action (navigation, JS execution, file/URI access) with no validation.
4. Observe the evidence. Trigger the vulnerable action and read the evidence panel - it prints the concrete proof (leaked value, accepted replay, executed payload, or unauthorized result).
5. Contrast with the secure path. Run the module’s secure/hardened action (where provided) and confirm the same attack is rejected - this is what a correct implementation should do.
6. Map it back. Cross-reference the MASTG v2 test(s) MASTG-TEST-0289, MASTG-TEST-0292 for the canonical procedure and remediation.

Tools (optional)

• adb shell screencap
• scrcpy