# Android Anti-Instrumentation & SSL Pinning Bypass (Frida/Objection)

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This page provides a practical workflow to regain dynamic analysis against Android apps that detect/root‑block instrumentation or enforce TLS pinning. It focuses on fast triage, common detections, and copy‑pasteable hooks/tactics to bypass them without repacking when possible.

## Detection Surface (what apps check)

- Root checks: su binary, Magisk paths, getprop values, common root packages
- Frida/debugger checks (Java): Debug.isDebuggerConnected(), ActivityManager.getRunningAppProcesses(), getRunningServices(), scanning /proc, classpath, loaded libs
- Native anti‑debug: ptrace(), syscalls, anti‑attach, breakpoints, inline hooks
- Early init checks: Application.onCreate() or process start hooks that crash if instrumentation is present
- TLS pinning: custom TrustManager/HostnameVerifier, OkHttp CertificatePinner, Conscrypt pinning, native pins

## Step 1 — Quick win: hide root with Magisk DenyList

- Enable Zygisk in Magisk
- Enable DenyList, add the target package
- Reboot and retest

Many apps only look for obvious indicators (su/Magisk paths/getprop). DenyList often neutralizes naive checks.

References:
- Magisk (Zygisk & DenyList): https://github.com/topjohnwu/Magisk

## Step 2 — 30‑second Frida Codeshare tests

Try common drop‑in scripts before deep diving:

- anti-root-bypass.js
- anti-frida-detection.js
- hide_frida_gum.js

Example:

```bash
frida -U -f com.example.app -l anti-frida-detection.js
```

These typically stub Java root/debug checks, process/service scans, and native ptrace(). Useful on lightly protected apps; hardened targets may need tailored hooks.

- Codeshare: https://codeshare.frida.re/

## Automate with Medusa (Frida framework)

Medusa provides 90+ ready-made modules for SSL unpinning, root/emulator detection bypass, HTTP comms logging, crypto key interception, and more.

```bash
git clone https://github.com/Ch0pin/medusa
cd medusa
pip install -r requirements.txt
python medusa.py

# Example interactive workflow
show categories
use http_communications/multiple_unpinner
use root_detection/universal_root_detection_bypass
run com.target.app
```

Tip: Medusa is great for quick wins before writing custom hooks. You can also cherry-pick modules and combine them with your own scripts.

## Step 3 — Bypass init-time detectors by attaching late

Many detections only run during process spawn/onCreate(). Spawn‑time injection (-f) or gadgets get caught; attaching after UI loads can slip past.

```bash
# Launch the app normally (launcher/adb), wait for UI, then attach
frida -U -n com.example.app
# Or with Objection to attach to running process
aobjection --gadget com.example.app explore  # if using gadget
```

If this works, keep the session stable and proceed to map and stub checks.

## Step 4 — Map detection logic via Jadx and string hunting

Static triage keywords in Jadx:
- "frida", "gum", "root", "magisk", "ptrace", "su", "getprop", "debugger"

Typical Java patterns:

```java
public boolean isFridaDetected() {
    return getRunningServices().contains("frida");
}
```

Common APIs to review/hook:
- android.os.Debug.isDebuggerConnected
- android.app.ActivityManager.getRunningAppProcesses / getRunningServices
- java.lang.System.loadLibrary / System.load (native bridge)
- java.lang.Runtime.exec / ProcessBuilder (probing commands)
- android.os.SystemProperties.get (root/emulator heuristics)

## Step 5 — Runtime stubbing with Frida (Java)

Override custom guards to return safe values without repacking:

```js
Java.perform(() => {
  const Checks = Java.use('com.example.security.Checks');
  Checks.isFridaDetected.implementation = function () { return false; };

  // Neutralize debugger checks
  const Debug = Java.use('android.os.Debug');
  Debug.isDebuggerConnected.implementation = function () { return false; };

  // Example: kill ActivityManager scans
  const AM = Java.use('android.app.ActivityManager');
  AM.getRunningAppProcesses.implementation = function () { return java.util.Collections.emptyList(); };
});
```

Triaging early crashes? Dump classes just before it dies to spot likely detection namespaces:

```js
Java.perform(() => {
  Java.enumerateLoadedClasses({
    onMatch: n => console.log(n),
    onComplete: () => console.log('Done')
  });
});
```

// Quick root detection stub example (adapt to target package/class names)
Java.perform(() => {
  try {
    const RootChecker = Java.use('com.target.security.RootCheck');
    RootChecker.isDeviceRooted.implementation = function () { return false; };
  } catch (e) {}
});

Log and neuter suspicious methods to confirm execution flow:

```js
Java.perform(() => {
  const Det = Java.use('com.example.security.DetectionManager');
  Det.checkFrida.implementation = function () {
    console.log('checkFrida() called');
    return false;
  };
});
```

## Bypass emulator/VM detection (Java stubs)

Common heuristics: Build.FINGERPRINT/MODEL/MANUFACTURER/HARDWARE containing generic/goldfish/ranchu/sdk; QEMU artifacts like /dev/qemu_pipe, /dev/socket/qemud; default MAC 02:00:00:00:00:00; 10.0.2.x NAT; missing telephony/sensors.

Quick spoof of Build fields:
```js
Java.perform(function(){
  var Build = Java.use('android.os.Build');
  Build.MODEL.value = 'Pixel 7 Pro';
  Build.MANUFACTURER.value = 'Google';
  Build.BRAND.value = 'google';
  Build.FINGERPRINT.value = 'google/panther/panther:14/UP1A.231105.003/1234567:user/release-keys';
});
```

Complement with stubs for file existence checks and identifiers (TelephonyManager.getDeviceId/SubscriberId, WifiInfo.getMacAddress, SensorManager.getSensorList) to return realistic values.

## SSL pinning bypass quick hook (Java)

Neutralize custom TrustManagers and force permissive SSL contexts:
```js
Java.perform(function(){
  var X509TrustManager = Java.use('javax.net.ssl.X509TrustManager');
  var SSLContext = Java.use('javax.net.ssl.SSLContext');

  // No-op validations
  X509TrustManager.checkClientTrusted.implementation = function(){ };
  X509TrustManager.checkServerTrusted.implementation = function(){ };

  // Force permissive TrustManagers
  var TrustManagers = [ X509TrustManager.$new() ];
  var SSLContextInit = SSLContext.init.overload('[Ljavax.net.ssl.KeyManager;','[Ljavax.net.ssl.TrustManager;','java.security.SecureRandom');
  SSLContextInit.implementation = function(km, tm, sr){
    return SSLContextInit.call(this, km, TrustManagers, sr);
  };
});
```

Notes
- Extend for OkHttp: hook okhttp3.CertificatePinner and HostnameVerifier as needed, or use a universal unpinning script from CodeShare.
- Run example: `frida -U -f com.target.app -l ssl-bypass.js --no-pause`

## Step 6 — Follow the JNI/native trail when Java hooks fail

Trace JNI entry points to locate native loaders and detection init:

```bash
frida-trace -n com.example.app -i "JNI_OnLoad"
```

Quick native triage of bundled .so files:

```bash
# List exported symbols & JNI
nm -D libfoo.so | head
objdump -T libfoo.so | grep Java_
strings -n 6 libfoo.so | egrep -i 'frida|ptrace|gum|magisk|su|root'
```

Interactive/native reversing:
- Ghidra: https://ghidra-sre.org/
- r2frida: https://github.com/nowsecure/r2frida

Example: neuter ptrace to defeat simple anti‑debug in libc:

```js
const ptrace = Module.findExportByName(null, 'ptrace');
if (ptrace) {
  Interceptor.replace(ptrace, new NativeCallback(function () {
    return -1; // pretend failure
  }, 'int', ['int', 'int', 'pointer', 'pointer']));
}
```

See also:
{{#ref}}
reversing-native-libraries.md
{{#endref}}

## Step 7 — Objection patching (embed gadget / strip basics)

When you prefer repacking to runtime hooks, try:

```bash
objection patchapk --source app.apk
```

Notes:
- Requires apktool; ensure a current version from the official guide to avoid build issues: https://apktool.org/docs/install
- Gadget injection enables instrumentation without root but can still be caught by stronger init‑time checks.

Optionally, add LSPosed modules and Shamiko for stronger root hiding in Zygisk environments, and curate DenyList to cover child processes.

References:
- Objection: https://github.com/sensepost/objection

## Step 8 — Fallback: Patch TLS pinning for network visibility

If instrumentation is blocked, you can still inspect traffic by removing pinning statically:

```bash
apk-mitm app.apk
# Then install the patched APK and proxy via Burp/mitmproxy
```

- Tool: https://github.com/shroudedcode/apk-mitm
- For network config CA‑trust tricks (and Android 7+ user CA trust), see:

  {{#ref}}
  make-apk-accept-ca-certificate.md
  {{#endref}}

  {{#ref}}
  install-burp-certificate.md
  {{#endref}}

## Handy command cheat‑sheet

```bash
# List processes and attach
frida-ps -Uai
frida -U -n com.example.app

# Spawn with a script (may trigger detectors)
frida -U -f com.example.app -l anti-frida-detection.js

# Trace native init
frida-trace -n com.example.app -i "JNI_OnLoad"

# Objection runtime
objection --gadget com.example.app explore

# Static TLS pinning removal
apk-mitm app.apk
```

## Universal proxy forcing + TLS unpinning (HTTP Toolkit Frida hooks)

Modern apps often ignore system proxies and enforce multiple layers of pinning (Java + native), making traffic capture painful even with user/system CAs installed. A practical approach is to combine universal TLS unpinning with proxy forcing via ready-made Frida hooks, and route everything through mitmproxy/Burp.

Workflow
- Run mitmproxy on your host (or Burp). Ensure the device can reach the host IP/port.
- Load HTTP Toolkit’s consolidated Frida hooks to both unpin TLS and force proxy usage across common stacks (OkHttp/OkHttp3, HttpsURLConnection, Conscrypt, WebView, etc.). This bypasses CertificatePinner/TrustManager checks and overrides proxy selectors, so traffic is always sent via your proxy even if the app explicitly disables proxies.
- Start the target app with Frida and the hook script, and capture requests in mitmproxy.

Example
```bash
# Device connected via ADB or over network (-U)
# See the repo for the exact script names & options
frida -U -f com.vendor.app \
  -l ./android-unpinning-with-proxy.js \
  --no-pause

# mitmproxy listening locally
mitmproxy -p 8080
```

Notes
- Combine with a system-wide proxy via `adb shell settings put global http_proxy <host>:<port>` when possible. The Frida hooks will enforce proxy use even when apps bypass global settings.
- This technique is ideal when you need to MITM mobile-to-IoT onboarding flows where pinning/proxy avoidance is common.
- Hooks: https://github.com/httptoolkit/frida-interception-and-unpinning

## References

- [Reversing Android Apps: Bypassing Detection Like a Pro](https://www.kayssel.com/newsletter/issue-12/)
- [Frida Codeshare](https://codeshare.frida.re/)
- [Objection](https://github.com/sensepost/objection)
- [apk-mitm](https://github.com/shroudedcode/apk-mitm)
- [Jadx](https://github.com/skylot/jadx)
- [Ghidra](https://ghidra-sre.org/)
- [r2frida](https://github.com/nowsecure/r2frida)
- [Apktool install guide](https://apktool.org/docs/install)
- [Magisk](https://github.com/topjohnwu/Magisk)
- [Medusa (Android Frida framework)](https://github.com/Ch0pin/medusa)
- [Build a Repeatable Android Bug Bounty Lab: Emulator vs Magisk, Burp, Frida, and Medusa](https://www.yeswehack.com/learn-bug-bounty/android-lab-mobile-hacking-tools)

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