Deep Link Authentication Bypass

← Insecure Authentication / Authorization

deeplink_authentication_bypass   MEDIUM

Description

A deep link routes directly to an authenticated screen/function, skipping the app-lock / login gate the normal navigation path enforces (Groww CVE-2026-12065 class).

How it works

A deep link routes directly to an authenticated screen (dvma://wallet, dvma://transfer), skipping the app-lock / login gate the normal in-app navigation enforces. The vulnerable router honors the requested target without checking whether the user is authenticated, so an attacker- triggered link opens the wallet and returns its balance while the user is logged out (the Groww CVE-2026-12065 class). The secure router enforces the auth gate and redirects protected routes to login.

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 Authentication / Authorization 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, drozer, jadx · iOS: xcrun simctl openurl, idb.
2. Locate the target. From the home index, open Deep Link Authentication Bypass (deeplink_authentication_bypass). 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. Drive the authentication/authorization path, capture the token / assertion / decision, then replay or tamper with it (mitmproxy, a WebAuthn test harness, or by editing the value) and confirm the server-side check accepts the manipulated request.
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-0371, MASTG-TEST-0370 for the canonical procedure and remediation.

Tools (optional)

Android

• adb
• drozer
• jadx

iOS

• xcrun simctl openurl
• idb