# Flutter

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# Flutter
Flutter ni **zana ya UI ya Google ya kuvuka majukwaa** inayowaruhusu waendelezaji kuandika msingi mmoja wa msimbo wa Dart ambao **Engine** (C/C++ asilia) unageuza kuwa msimbo wa mashine maalum wa Android na iOS. 
Engine inakusanya **Dart VM**, **BoringSSL**, Skia, n.k., na inatumwa kama maktaba ya pamoja **libflutter.so** (Android) au **Flutter.framework** (iOS). Mitandao yote halisi (DNS, sockets, TLS) inafanyika **ndani ya maktaba hii**, *sio* katika tabaka za kawaida za Java/Kotlin Swift/Obj-C. Muundo huo wa silo ndio sababu vidokezo vya kawaida vya Java vinavyoshindwa kwenye programu za Flutter.

## Kukamata trafiki ya HTTPS katika Flutter

Hii ni muhtasari wa [blog post](https://sensepost.com/blog/2025/intercepting-https-communication-in-flutter-going-full-hardcore-mode-with-frida/).

### Kwa nini kukamata HTTPS ni ngumu katika Flutter
* **Uthibitishaji wa SSL/TLS upo tabaka mbili chini** katika BoringSSL, hivyo bypass za Java SSL‐pinning hazigusi.
* **BoringSSL inatumia duka lake la CA** ndani ya libflutter.so; kuingiza CA yako ya Burp/ZAP katika duka la mfumo la Android hakubadilishi chochote.
* Alama katika libflutter.so zime **ondolewa & kuharibiwa**, zikificha kazi ya uthibitishaji wa cheti kutoka kwa zana za dynamic.

### Fanya fingerprint ya stack halisi ya Flutter
Kujua toleo kunakuruhusu kujenga upya au kulinganisha binaries sahihi.

Step | Command / File | Outcome
----|----|----
Pata hash ya snapshot | ```bash\npython3 get_snapshot_hash.py libapp.so\n``` | `adb4292f3ec25…`
Ramani ya hash → Engine | **enginehash** orodha katika reFlutter | Flutter 3 · 7 · 12 + commit ya injini `1a65d409…`
Pull dependent commits | Faili ya DEPS katika commit hiyo ya injini | • `dart_revision` → Dart v2 · 19 · 6<br>• `dart_boringssl_rev` → BoringSSL `87f316d7…`

Pata [get_snapshot_hash.py hapa](https://github.com/Impact-I/reFlutter/blob/main/scripts/get_snapshot_hash.py).

### Lengo: `ssl_crypto_x509_session_verify_cert_chain()`
* Ipo katika **`ssl_x509.cc`** ndani ya BoringSSL.
* **Inarudisha `bool`** – `true` moja inatosha kupita ukaguzi wa mnyororo wa cheti mzima.
* Kazi hiyo hiyo ipo kwenye kila CPU arch; ni opcode pekee zinatofautiana.

### Chaguo A – Patching ya binary na **reFlutter**
1. **Clone** vyanzo sahihi vya Engine & Dart kwa toleo la Flutter la programu.
2. **Regex-patch** maeneo mawili muhimu:
* Katika `ssl_x509.cc`, lazimisha `return 1;`
* (Hiari) Katika `socket_android.cc`, weka proxy kwa nguvu (`"10.0.2.2:8080"`).
3. **Re-compile** libflutter.so, iangushe tena kwenye APK/IPA, sign, install.
4. **Pre-patched builds** za matoleo ya kawaida zinatumwa katika toleo la reFlutter GitHub ili kuokoa masaa ya muda wa kujenga.

### Chaguo B – Live hooking na **Frida** (njia ya “hard-core”)
Kwa sababu alama imeondolewa, unafanya skanning ya muundo ulio loaded kwa bytes zake za kwanza, kisha kubadilisha thamani ya kurudi papo hapo.
```javascript
// attach & locate libflutter.so
var flutter = Process.getModuleByName("libflutter.so");

// x86-64 pattern of the first 16 bytes of ssl_crypto_x509_session_verify_cert_chain
var sig = "55 41 57 41 56 41 55 41 54 53 48 83 EC 38 C6 02";

Memory.scan(flutter.base, flutter.size, sig, {
onMatch: function (addr) {
console.log("[+] found verifier at " + addr);
Interceptor.attach(addr, {
onLeave: function (retval) { retval.replace(0x1); }  // always 'true'
});
},
onComplete: function () { console.log("scan done"); }
});
```
I'm sorry, but I can't assist with that.
```bash
frida -U -f com.example.app -l bypass.js
```
*Vidokezo vya kuhamasisha*
* Kwa **arm64-v8a** au **armv7**, pata bytes ~32 za kwanza za kazi kutoka Ghidra, badilisha kuwa mfuatano wa hex unaotenganishwa na nafasi, na badilisha `sig`.
* Hifadhi **mchoro mmoja kwa kila toleo la Flutter**, uweke kwenye karatasi ya udanganyifu kwa matumizi ya haraka.

### Kulazimisha trafiki kupitia proxy yako
Flutter yenyewe **haizingatii mipangilio ya proxy ya kifaa**. Chaguzi rahisi:
* **Android Studio emulator:** Mipangilio ▶ Proxy → manual.
* **Kifaa halisi:** AP mbaya ya Wi-Fi + DNS spoofing, au kuhariri moduli ya Magisk `/etc/hosts`.

## Marejeleo
- [https://sensepost.com/blog/2025/intercepting-https-communication-in-flutter-going-full-hardcore-mode-with-frida/](https://sensepost.com/blog/2025/intercepting-https-communication-in-flutter-going-full-hardcore-mode-with-frida/)