---
# System prepended metadata

title: Pentest Bug Report

---

# Pentest Bug Report

## 1) Report Metadata

- **Project / Application Name:** `NDAKey SDK v1.2.0`
- **Environment:** `Dev API (https://api-dev.ndakey.vn/sdk/) + Android demo app (self-built debug APK)`
- **Assessment Type:** `Gray-box Mobile + API Pentest`
- **Client / Owner:** `xxx`
- **Tester(s):** `Vo Tran Minh`
- **Report Date:** `2026-04-13`
- **Test Window:** `2026-04-06 to 2026-04-10`

---

## 2) Executive Summary

### 2.1 Scope (What object was tested)
- SDK artifacts: `ndakey-1.2.0.aar`, `ndakey-1.2.0-sources.jar`, decompiled sources in `aar_content/jadx_out/` and `jar_content/main/`.
- Runtime validation target: `demo-ndakey/` Android application.
- Security PoCs under: `pocs/`.
- API target: passkey endpoints under `/sdk/api/v1/*`.

### 2.2 Who
- **Requested by:** `xxx`
- **Tested by:** `Vo Tran Minh`

### 2.3 When
- **Testing period:** `2026-04-06 to 2026-04-10 (ICT, UTC+7)`
- **Retest date (if any):** `Pending`

### 2.4 High-Level Risk Summary
- **Critical:** `4`
- **High:** `4`
- **Medium:** `0`
- **Low:** `0` 

---

## 3) Bug Index

| ID | Bug Title | Affected Object | Severity | Status |
|---|---|---|---|---|
| NDA-CRYPTO-001 | AES-GCM fixed IV | KeyStore encryption flow | Critical | Confirmed |
| NDA-CRYPTO-002 | Hardcoded AES-CBC key/IV | Network crypto constants/util | Critical | Confirmed |
| NDA-CRYPTO-003 | AES-ECB pattern leakage | Pre-M crypto mode | High | Confirmed |
| NDA-CRYPTO-004 | Embedded RSA private key in client | RSA utility | Critical | Confirmed |
| NDA-CRYPTO-005 | DIDComm/JWE `tag` leaks key bytes | DIDComm encryptor | Critical | Confirmed |
| NDA-APP-006 | Decrypted plaintext logged | SDK client runtime logging | High | Confirmed |
| NDA-API-007 | Passkey begin endpoints without auth | `/api/v1/passkey/registration-begin`, `/api/v1/passkey/login-begin` | High | Confirmed |
| NDA-API-008 | Over-permissive CORS on passkey begin | Passkey begin endpoints | High | Confirmed |

> Exploit evidence (PoC/image/vulnerable code) is documented in each **Detailed Bug Entry** section.

---

## 4) Detailed Bug Entries

### NDA-CRYPTO-001 — AES-GCM fixed IV (nonce reuse)
- **Overview:** SDK reuses a fixed IV in AES-GCM, which breaks nonce uniqueness.
- **Code (path:line):** `aar_content/jadx_out/sources/com/ndakey/sdk/core/utils/KeyStoreUtils.java:100,314`
```java
private static final byte[] FIXED_IV = {80, -90, 78, 98, 17, 106, 7, 69, -58, 50, -46, -14};
cipher.init(1, getSecretKeyAPIMorGreater(), new GCMParameterSpec(128, FIXED_IV));
```
- **Exploit evidence:** `python3 pocs/poc_fixed_iv_gcm.py`.

![crypt01](https://hackmd.io/_uploads/S1JTf4qnZe.png)


### NDA-CRYPTO-002 — Hardcoded AES-CBC key/IV
- **Overview:** AES key and IV are hardcoded in client code, allowing offline decrypt/forge.
- **Code (path:line):** `.../network/Constants.java:15`, `.../SecurityUtil.java:97-129`
```java
public static final String secretKey = "f5d68e3f5b25d673d81a6d7c6a2c912e";
public static final String iv = "5b16f7d6d19e5a9c";
```
- **Exploit evidence:** `python3 pocs/poc_hardcoded_aes_cbc.py`.

![crypt02](https://hackmd.io/_uploads/B1cpzVcnbe.png)


### NDA-CRYPTO-003 — AES-ECB pattern leakage
- **Overview:** SDK uses ECB mode (pre-M), which leaks block patterns.
- **Code (path:line):** `aar_content/jadx_out/sources/com/ndakey/sdk/core/utils/KeyStoreUtils.java:63`
```java
private static final String AES_MODE_LESS_THAN_M = "AES/ECB/PKCS7Padding";
```
- **Exploit evidence:** `python3 pocs/poc_ecb_pattern_leak.py`.


![crypt03](https://hackmd.io/_uploads/SkKDXNq2be.png)


### NDA-CRYPTO-004 — Embedded RSA private key in client
- **Overview:** Private RSA key is embedded in app code and can be extracted.
- **Code (path:line):** `aar_content/jadx_out/sources/com/ndakey/sdk/core/utils/RSACryptData.java:33`
```java
private static final String PRIVATE_KEY_STRING = "MIICdgIBADANBgkq...";
```
- **Exploit evidence:** `python3 pocs/poc_embedded_rsa_private_key.py`.


![crypt04](https://hackmd.io/_uploads/Bk9bX4qnbg.png)



### NDA-CRYPTO-005 — DIDComm/JWE `tag` leaks key bytes
- **Overview:** `tag` is derived from key material instead of proper AEAD auth tag.
- **Code (path:line):** `aar_content/jadx_out/sources/com/ndakey/sdk/core/didcommcrypto/AesGcmEncryptor.java:71`
```java
jSONObject.put("tag", strEncodeToString);
```
- **Exploit evidence:** `python3 pocs/poc_didcomm_fake_tag_leak.py`.


![crypt05](https://hackmd.io/_uploads/Sk9kmV93-e.png)


### NDA-APP-006 — Decrypted plaintext logged
- **Overview:** SDK logs decrypted sensitive plaintext to logcat.
- **Code (path:line):** `jar_content/main/com/ndakey/sdk/core/NdaKeyClient.kt:71`
```kotlin
Log.d("dataDecrypt", dataDecrypt)
```
- **Exploit evidence:** runtime demo + `adb logcat -d | grep dataDecrypt`.

![app06](https://hackmd.io/_uploads/rJGmmEc3We.png)


### NDA-API-007 — Passkey begin endpoints without auth
- **Overview:** Begin endpoints can be called without Authorization/API key.
- **Code (path:line):** `jar_content/main/com/ndakey/sdk/core/network/APIs.kt:56,66`
```kotlin
@POST("api/v1/passkey/registration-begin")
@POST("api/v1/passkey/login-begin")
```
- **Exploit evidence:** unauthenticated curl/python probing returned `HTTP 200`.

![api07](https://hackmd.io/_uploads/rksXQVqhZl.png)


### NDA-API-008 — Over-permissive CORS on passkey begin
- **Overview:** CORS policy reflects origin and allows wildcard methods/headers.
- **Code (path:line):** `jar_content/main/com/ndakey/sdk/core/network/APIs.kt:56,66` (affected endpoints)
```kotlin
@POST("api/v1/passkey/registration-begin")
@POST("api/v1/passkey/login-begin")
```
- **Exploit evidence:** OPTIONS preflight showed reflected `access-control-allow-origin`, wildcard allow-headers/methods.


![api08](https://hackmd.io/_uploads/B18Hm492Wl.png)