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

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Ova stranica daje praktičan workflow za povraćaj dinamičke analize nad Android aplikacijama koje detektuju/sprečavaju instrumentation zbog root-a ili nameću TLS pinning. Fokusira se na brzu trijažu, uobičajene detekcije i kopiraj‑zalepi hookove/taktike za zaobilaženje bez repackovanja kad je to moguće.

## 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

Mnoge aplikacije traže samo očigledne indikatore (su/Magisk paths/getprop). DenyList često neutralizuje naivne provere.

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

## Step 2 — 30‑second Frida Codeshare tests

Probaj uobičajene drop‑in skripte pre nego što kreneš u dublju analizu:

- 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
```
Oni obično stubuju Java root/debug checks, process/service scans i native ptrace(). Korisno za slabo zaštićene apps; hardened targets mogu zahtevati tailored hooks.

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

## Korak 3 — Zaobiđite detektore pri inicijalizaciji priključivanjem kasnije

Mnoga detekcija se izvršavaju samo tokom process spawn/onCreate(). Spawn‑time injection (-f) ili gadgets bivaju otkriveni; priključivanje nakon učitavanja UI‑a može promaći.
```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
```
Ako ovo radi, održi sesiju stabilnom i nastavi sa mapiranjem i stub proverama.

## Korak 4 — Mapiraj logiku detekcije preko Jadx i pretragom stringova

Ključne reči za statičku trijažu u Jadx:
- "frida", "gum", "root", "magisk", "ptrace", "su", "getprop", "debugger"

Tipični Java obrasci:
```java
public boolean isFridaDetected() {
return getRunningServices().contains("frida");
}
```
Uobičajeni API-jevi za 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)

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

Override custom guards da vraćaju sigurne vrednosti bez repacking-a:
```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(); };
});
```
Trijaža ranih padova? Dump-ujte klase neposredno pre nego što aplikacija padne da biste uočili verovatne detection namespaces:
```js
Java.perform(() => {
Java.enumerateLoadedClasses({
onMatch: n => console.log(n),
onComplete: () => console.log('Done')
});
});
```
Zabeležite i onesposobite sumnjive metode da potvrdite tok izvršavanja:
```js
Java.perform(() => {
const Det = Java.use('com.example.security.DetectionManager');
Det.checkFrida.implementation = function () {
console.log('checkFrida() called');
return false;
};
});
```
## Korak 6 — Pratite JNI/native trag kada Java hooks zakažu

Pratite JNI ulazne tačke da biste pronašli native loaders i detection init:
```bash
frida-trace -n com.example.app -i "JNI_OnLoad"
```
Brza nativna trijaža priloženih .so datoteka:
```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'
```
Interaktivno / native reversing:
- Ghidra: https://ghidra-sre.org/
- r2frida: https://github.com/nowsecure/r2frida

Primer: onesposobiti ptrace da bi se zaobišao jednostavan anti‑debug u 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']));
}
```
Vidi takođe:
{{#ref}}
reversing-native-libraries.md
{{#endref}}

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

Ako više volite repacking umesto runtime hooks, pokušajte:
```bash
objection patchapk --source app.apk
```
Napomene:
- Zahteva apktool; obezbedite aktuelnu verziju iz zvaničnog vodiča da biste izbegli probleme pri buildovanju: https://apktool.org/docs/install
- Gadget injection omogućava instrumentation bez root-a, ali može biti otkrivena jačim init‑time checks.

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

## Korak 8 — Plan B: Uklonite TLS pinning radi vidljivosti mreže

Ako je instrumentation blokirana, i dalje možete da pregledate saobraćaj tako što ćete statički ukloniti pinning:
```bash
apk-mitm app.apk
# Then install the patched APK and proxy via Burp/mitmproxy
```
- Alat: https://github.com/shroudedcode/apk-mitm
- Za trikove vezane za network config CA‑trust (i Android 7+ user CA trust), vidi:

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

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

## Koristan spisak komandi
```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
```
## Saveti i napomene

- Preferirajte attach kasnije umesto spawn-ovanja kada apps crash-uju pri launch-u
- Neki detections se ponovo pokreću u kritičnim flow-ovima (npr. payment, auth) — držite hooks aktivnim tokom navigacije
- Mešajte static i dynamic: string hunt u Jadx da suzite listu klasa; zatim hook-ujte metode da verifikujete u runtime-u
- Hardened apps mogu koristiti packers i native TLS pinning — očekujte da reverse-ujete native code

## Reference

- [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)

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