Proximity Transfer Unsafe Parsing (AirDrop / Quick Share)

← Improper Platform Usage

proximity_transfer_unsafe_parsing   HARD

Description

The app parses an untrusted, pre-authentication proximity-transfer payload (AirDrop / Quick Share plist / XML / archive) with a naive, unbounded parser, so a malformed plist, a deeply-nested XML recursion bomb, or a decompression bomb causes resource exhaustion / state-machine confusion with no prior pairing (AirDrop & Quick Share proximity-protocol research class).

How it works

The app parses an untrusted, pre-authentication proximity-transfer payload (an AirDrop or Quick Share plist, XML, or archive) with a naive, unbounded parser: no pairing, no size cap, no recursion-depth cap, no entity-expansion cap. A tiny deeply-nested “billion laughs” entity bomb therefore expands to a colossal node count and exhausts memory with no prior interaction. On Android a compiled-C TLV parser over-reads on a lying length field; on every host a real recursive entity expander materializes a genuine billion-laughs XML in memory and reports the observed byte blowup. The secure path enforces a max depth, a max entity-expansion, and a max size, rejecting the bomb before it can expand.

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 emulator/simulator you control. The demo needs no external tooling; for the optional on-device reproduction the relevant tools are: radamsa · Android: Quick Share · iOS: AirDrop.
2. Locate the target. From the home index, open Proximity Transfer Unsafe Parsing (AirDrop / Quick Share) (proximity_transfer_unsafe_parsing). 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.

Tools (optional)

• radamsa

Android

• Quick Share

iOS

• AirDrop

Attack inputs

Payloads/artifacts you author for the on-device attack. The demo already ships and simulates these in-process (e.g. the malicious companion app / crafted intent is emulated inside the screen), so you only need to craft them to reproduce the exploit on a real device:

• crafted plist

Real-world references

Concrete public disclosures that match this vulnerability class:

• Protocol Prying: AirDrop & Quick Share proximity-protocol vulnerabilities