Insecure Backups (allowBackup / unencrypted iOS backups)

← Insecure Data Storage

insecure_backups   EASY

Description

android:allowBackup=true and no iOS backup exclusion leak app data to backups.

How it works

android:allowBackup=true with no backup rules (and no iOS NSURLIsExcludedFromBackupKey) means a full device backup captures the whole app sandbox: tokens, databases, and PII. The app writes a JSON blob of tokens and PII into the app documents directory, which is part of the sandbox a backup sweeps up, so the real exploit is a full device backup pulling exactly this file. The secure path excludes sensitive files from backup and disables unconditional backup of the sandbox.

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 Insecure Data Storage category (e.g. --dart-define-from-file=config/flavors/dev.json) and run on an emulator/simulator you control. The demo needs no external tooling; for the optional on-device reproduction the relevant tools are: Android: adb backup, apktool · iOS: idevicebackup2, ifuse, plist inspection.
2. Locate the target. From the home index, open Insecure Backups (allowBackup / unencrypted iOS backups) (insecure_backups). 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. Exercise the flow that persists data, then inspect on-device storage (adb shell run-as <pkg> / pull the app sandbox, or objection’s android keystore/ios nsuserdefaults helpers) and confirm the sensitive value is present in cleartext or without hardware backing.
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-0216, MASTG-TEST-0215, MASTG-TEST-0262, MASTG-TEST-0298 for the canonical procedure and remediation.

Tools (optional)

Android

• adb backup
• apktool

iOS

• idevicebackup2
• ifuse
• plist inspection