安卓协议逆向 cxdx 分析与实现
VSole2023-03-24 10:16:09
一、Kit
app 版本：5.0.0
设备：K40 刷 piexl 11 rom
抓包工具：Charles
反汇编工具：JEB、JADX、IDA
inject：frida
二、抓包
POST /v1/api/app/login/doLogin HTTP/1.1X-OsVersion: 30User-Agent: Mozilla/5.0 (Linux; Android 11; M2012K11AC Build/RQ3A.211001.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/108.0.5359.128 Mobile Safari/537.36 CSDNApp/5.0.0(Android)wToken/0.0.1X-RandomNum: 54736X-Access-Token: 00871d5df0d4f51efb5883b3b2fd2359platform: androidX-Ca-Signature-Headers: X-Ca-Timestamp,X-Ca-Key,X-Ca-NonceAuthorization:X-OS: Androidc_appVersion: 5.0.0X-App-ID: CSDN-APPX-App-Theme: daycontent-type: application/json; charset=UTF-8X-Ca-Signature: BqhPpXbobBOndykiyCtOVK06GHLkfLbs1y4B3Ek0gnY=X-ConnectionType: WIFIUserToken:X-TimeStamp: 1671939318488Cookie: UserName=;UserToken=X-Ca-Key: 203789067Accept: application/jsonX-Device-ID: aid0f0fef992b53479187546b3c621157f0wToken: e447_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&ff4b_85475962D8E15A4E7AE60ED42FF3568E8EDB86EE620E495591X-DeviceModel: Redmi M2012K11ACversion: 5.0.0X-Ca-Nonce: be0eca5c-e959-4b0f-b4e7-22e00118157eX-Ca-Timestamp: 1671939318489X-Sign: 70B21B02FD0EFD2353F0D7F4F2E7CDB6FC1C3C42Host: passport.csdn.netConnection: Keep-AliveAccept-Encoding: gzipContent-Length: 95{"pwdOrVerifyCode":"123456","loginType":"1","userIdentification":"17750659921","checkAli":true}
意料之中一大堆参数，反复几次总结需分析的参数应该为以下几个：
X-Sign、wToken、X-Ca-Signature、X-Access-Token、X-Ca-Timestamp
三、分析
先搜索 X-Sign，就一处。
跟进得：
public static Map z(String url, Map requestMap) { String str; String a2 = wo3.a(CSDNApp.csdnApp); HashMap hashMap = new HashMap(); hashMap.put("platform", "android"); hashMap.put("version", xn3.u()); hashMap.put("c_appVersion", xn3.u()); if (!TextUtils.isEmpty(it3.g())) { hashMap.put("JWT-TOKEN", it3.g()); no3.a("==JWT-TOKEN==", it3.g()); } hashMap.put("Authorization", StringUtils.isEmpty(it3.g()) ? "" : "Bearer " + it3.g()); hashMap.put("X-Device-ID", a2); hashMap.put("X-OS", "Android"); hashMap.put("X-App-ID", "CSDN-APP"); hashMap.put("X-Access-Token", MD5.md5(a2 + "AndroidCSDN-APPb85fF96d-7Aa4-4Ec1-bf1D-2133c1A45656")); hashMap.put("X-OsVersion", Build.VERSION.SDK_INT + ""); String str2 = Build.BRAND + Operators.SPACE_STR + Build.MODEL; int length = str2.length(); for (int i = 0; i < length; i++) { char charAt = str2.charAt(i); if ((charAt <= 31 && charAt != '\t') || charAt >= 127) { str2.replace(charAt, ' '); } } hashMap.put("X-DeviceModel", str2); hashMap.put("X-ConnectionType", yp3.b(CSDNApp.csdnApp)); hashMap.put("UserToken", StringUtils.isEmpty(it3.q()) ? "" : it3.q()); hashMap.put("X-App-Theme", CSDNApp.isDayMode ? "day" : "night"); int c2 = xn3.c(10000, 99999); String str3 = new Date().getTime() + ""; try { str = mq3.a(a2 + c2 + str3 + zf1.o); } catch (DigestException e2) { e2.printStackTrace(); str = ""; } hashMap.put("X-Sign", str); hashMap.put("X-RandomNum", c2 + ""); hashMap.put("X-TimeStamp", str3); StringBuilder sb = new StringBuilder(); sb.append("UserName="); sb.append(it3.p()); sb.append(";UserToken="); sb.append(StringUtils.isEmpty(it3.q()) ? "" : it3.q()); hashMap.put(IWebview.COOKIE, sb.toString()); if (!StringUtils.isEmpty(url) && requestMap != null && requestMap.containsKey("category")) { hashMap.put("X-PageKey", "blog." + requestMap.get("category")); hashMap.put("X-Path", "app.csdn.net/blog/" + requestMap.get("category")); } if (!StringUtils.isEmpty(url) && url.equals(s22.G0)) { hashMap.put("X-PageKey", vr3.Q6); hashMap.put("X-Path", "app.csdn.net/blog/detail"); if (requestMap != null && requestMap.containsKey("from")) { hashMap.put("X-Referer", "blog." + requestMap.get("from")); } } hashMap.put("User-Agent", CSDNApp.csdnApp.userAgent + " CSDNApp/" + xn3.u() + "(Android)wToken/0.0.1"); try { hashMap.put("wToken", TigerTallyAPI.vmpSign(1, str3.getBytes("UTF-8"))); } catch (UnsupportedEncodingException e3) { e3.printStackTrace(); } return hashMap;}
pretty nice，很多参数都在这里，那就从上往下分析：
hashMap.put("platform", "android"); // 固定值hashMap.put("version", xn3.u()); // 固定值hashMap.put("c_appVersion", xn3.u()); // 固定值hashMap.put("Authorization", StringUtils.isEmpty(it3.g()) ? "" : "Bearer " + it3.g()); // 无用，请求头中为空hashMap.put("X-Device-ID", a2); // a2 在 String a2 = wo3.a(CSDNApp.csdnApp);
hook wo3.a看看：
function main() { Java.perform(function () { var wo3 = Java.use("wo3"); wo3["a"].implementation = function (context) { console.log('a is called' + ', ' + 'context: ' + context); var ret = this.a(context); console.log('a ret value is ' + ret); return ret; }; });}setImmediate(main)
结果：
a is called, context: net.csdn.csdnplus.CSDNApp@dc96acba ret value is aid0f0fef992b53479187546b3c621157f0
多次 hook 该值并没有改变，查看不同数据包的内容也是一样的，但在 Java 层仅分析到 aid 复制点，后面数据同一设备都是一样的，怀疑是消息散列值，有可能是 DeviceID 或者 UUID，有在 Java 层看到，但 hook 不到，往下分析：
hashMap.put("X-OS", "Android"); // 固定值hashMap.put("X-App-ID", "CSDN-APP"); // 固定值hashMap.put("X-Access-Token", MD5.md5(a2 + "AndroidCSDN-APPb85fF96d-7Aa4-4Ec1-bf1D-2133c1A45656")); // a2 就是上面的 X-Device-ID 再进行加盐处理后进行 MD5 加密复现一下：
from hashlib import md5 def encrypt_md5(mes): new_md5 = md5() # 这里必须用encode()函数对字符串进行编码，不然会报 TypeError: Unicode-objects must be encoded before hashing new_md5.update(mes.encode(encoding='utf-8')) # 加密 return new_md5.hexdigest() if __name__ == '__main__': print(encrypt_md5('aid0f0fef992b53479187546b3c621157f0AndroidCSDN-APPb85fF96d-7Aa4-4Ec1-bf1D-2133c1A45656'))
结果 00871d5df0d4f51efb5883b3b2fd2359，校验无误,继续往下：
hashMap.put("X-OsVersion", Build.VERSION.SDK_INT + ""); // sdk 版本吧，可随机的样子hashMap.put("X-DeviceModel", str2); // 通过上面获取来的，分析一下就是手机 + 手机名称hashMap.put("X-ConnectionType", yp3.b(CSDNApp.csdnApp)); // 网络连接类型hashMap.put("UserToken", StringUtils.isEmpty(it3.q()) ? "" : it3.q()); // 抓包为空值，放弃hashMap.put("X-App-Theme", CSDNApp.isDayMode ? "day" : "night"); // 主题模式hashMap.put("X-Sign", str);
str 是上面计算来的，拿来分析下：
int c2 = xn3.c(10000, 99999);String str3 = new Date().getTime() + "";try { str = mq3.a(a2 + c2 + str3 + zf1.o);} catch (DigestException e2) { e2.printStackTrace(); str = "";}hashMap.put("X-Sign", str);
c2：10000 - 99999 之间的随机值；str3：时间戳转字符串；a2：上面分析过为 X-Device-ID 值；zf1.o：跟进查看为定值：public static final String o = "F403F982CA92F73AC142D50FFA69853D";
参数搞定，看 mq3.a 方法：
public static String a(String decrypt) throws DigestException { try { MessageDigest messageDigest = MessageDigest.getInstance("SHA-1"); messageDigest.update(decrypt.getBytes()); byte[] digest = messageDigest.digest(); StringBuffer stringBuffer = new StringBuffer(); for (byte b : digest) { String hexString = Integer.toHexString(b & 255); if (hexString.length() < 2) { stringBuffer.append(0); } stringBuffer.append(hexString); } return stringBuffer.toString().toUpperCase(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); throw new DigestException("签名错误！"); }}
SHA1算法，先 hook 再还原：
function main() { Java.perform(function () { var mq3 = Java.use("mq3"); mq3["a"].implementation = function (decrypt) { console.log('a is called' + ', ' + 'decrypt: ' + decrypt); var ret = this.a(decrypt); console.log('a ret value is ' + ret); return ret; }; });}setImmediate(main)// frida -FU -l CSDN/csdn.js
结果：
a is called, decrypt:aid0f0fef992b53479187546b3c621157f0709751671957807054F403F982CA92F73AC142D50FFA69853Da ret value is E11539C9183644EEB69C7FEBAC1D58A2D874895C
还原：
import hashlib # 使用sha1加密算法，返回str加密后的字符串def sha1_secret_str(s: str): sha = hashlib.sha1(s.encode('utf-8')) encrypts = sha.hexdigest() return encrypts.upper() if __name__ == '__main__': # 待加密的字符串 s = 'aid0f0fef992b53479187546b3c621157f0709751671957807054F403F982CA92F73AC142D50FFA69853D' res = sha1_secret_str(s) print(res)
结果：E11539C9183644EEB69C7FEBAC1D58A2D874895C 校验无误，继续往下分析：
hashMap.put("X-RandomNum", c2 + ""); // 10000 - 99999 之间的随机值；hashMap.put("X-TimeStamp", str3); // str3：时间戳转字符串；hashMap.put(IWebview.COOKIE, sb.toString()); // 看抓包结果应该是 Cookie 值，对照结果 UserName=;UserToken= 啥操作没做，应该是要登录后才有值也是固定值hashMap.put("User-Agent", CSDNApp.csdnApp.userAgent + " CSDNApp/" + xn3.u() + "(Android)wToken/0.0.1");
对照其抓包内容：CSDNApp.csdnApp.userAgent 获取设备 header，xn3.u() 获取 app 版本号。
// Mozilla/5.0 (Linux; Android 11; M2012K11AC Build/RQ3A.211001.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/108.0.5359.128 Mobile Safari/537.36 CSDNApp/5.0.0(Android)wToken/0.0.1hashMap.put("wToken", TigerTallyAPI.vmpSign(1, str3.getBytes("UTF-8")));
看到 wToken 就有点不好的预感，应该是阿里安全的，前段时间很火的某box就是用的这个，跟进看看，最终定位到：
private static native String _genericNt3(int i, byte[] bArr);
so 层了，放着先看看别的参数吧，这块代码，能解决的参数都解决了，但 X-Ca-Signature 没在这出现，jadx 再搜跟到以下代码：
private static Map<String, String> c(StringBuilder strBuilder, Map<String, String> headerParams) { if (ft3.b() != 1) { headerParams.put("X-Ca-Stage", ft3.b() == 2 ? "TEST" : "PRE"); } try { Mac mac = Mac.getInstance("HmacSHA256"); byte[] bytes = y12.c.getBytes("UTF-8"); mac.init(new SecretKeySpec(bytes, 0, bytes.length, "HmacSHA256")); String str = new String(Base64.encodeBase64(mac.doFinal(strBuilder.toString().getBytes("UTF-8")))); headerParams.put("X-Ca-Signature", str); no3.a("==HmacSHA256==", str); } catch (UnsupportedEncodingException e2) { e2.printStackTrace(); } catch (InvalidKeyException e3) { e3.printStackTrace(); } catch (NoSuchAlgorithmException e4) { e4.printStackTrace(); } return headerParams;}
不难看出该值是通过 HmacSHA256 加密后再进行 Base64 编码后得到的结果，其 key 值为：
public static final String c = "0u94vkvsewic9kkgsp1r3nuq3ir0lv3n";hook 看看要加密 strBuilder 有啥：function main() { Java.perform(function () { var r12 = Java.use("r12"); r12["c"].implementation = function (strBuilder, headerParams) { console.log('strBuilder: ' + strBuilder); var ret = this.c(strBuilder, headerParams); var keyset = ret.keySet(); var result = ""; var it = keyset.iterator(); while (it.hasNext()) { var keystr = it.next().toString(); var valuestr = ret.get(keystr).toString(); console.log(keystr) console.log(valuestr) result += valuestr; } return ret; }; });}setImmediate(main)// frida -FU -l CSDN/csdn.js
结果：
strBuilder:POSTapplication/jsonapplication/json; charset=UTF-8X-Ca-Key:203789067X-Ca-Nonce:3339aae3-e295-410c-8345-52c9ebc56b5aX-Ca-Timestamp:1671963564343/v1/api/app/login/doLogin
其中 X-Ca-Key 是个定值：
headerParams.put("X-Ca-Key", y12.b);public static final String b = "203789067";X-Ca-Nonce 为 UUID 值：headerParams.put("X-Ca-Nonce", UUID.randomUUID().toString());X-Ca-Timestamp 为时间戳。
python还原算法，与抓包结果一致：
from hashlib import sha256import hmac, base64 def get_sign(data, key): key = key.encode('utf-8') message = data.encode('utf-8') sign = base64.b64encode(hmac.new(key, message, digestmod=sha256).digest()).decode() print(sign) return signif __name__ == '__main__': # 待加密的字符串 s = "POST" + "" + \ "application/json" + "" + \ "" + \ "application/json; charset=UTF-8" + "" + \ "" + \ "X-Ca-Key:203789067" + "" + \ "X-Ca-Nonce:3339aae3-e295-410c-8345-52c9ebc56b5a" + "" + \ "X-Ca-Timestamp:1671963564343" + "" + \ "/v1/api/app/login/doLogin" k = '0u94vkvsewic9kkgsp1r3nuq3ir0lv3n' res = get_sign(s, k) print(res)
抓包结果：QJYeguZxkE+ZojwTP0rIJ+IzjaSHI82uR2y0xOIG35U=
到这几乎参数都解决了，剩个 so 层的 wtoken，在 Java 层能够定位到：com/aliyun/TigerTally/TigerTallyAPI，其中，要找的就是 libtiger_tally.so 了：
static { System.loadLibrary("tiger_tally");}
换思路做吧，不想折腾，想了想我直接 rpc 调用不就好了。
四、rpc 远程调用
frida rpc 脚本：
var response = null;Java.enumerateClassLoaders({ onMatch: function (loader) { try { if (loader.findClass("com.aliyun.TigerTally.TigerTallyAPI")) { Java.classFactory.loader = loader; response = Java.use("com.aliyun.TigerTally.TigerTallyAPI") } else { } } catch (error) { } }, onComplete: function () { }}); function stringToByte (str) { var ch, st, re = []; for (var i = 0; i < str.length; i++ ) { ch = str.charCodeAt(i); st = []; do { st.push( ch & 0xFF ); ch = ch >> 8; } while ( ch ); re = re.concat(st.reverse()); } return re;} function getwwoken(data){ var result = response._genericNt3(1, stringToByte(data)); return result;} rpc.exports = { getwtoken:getwwoken}
补环境：
import timeimport hmacimport uuidimport randomimport base64from hashlib import sha256, md5, sha1 def get_x_osversion(): return "30" def get_x_os(): return "android" def get_x_appid(): return "CSDN_APP" def get_x_app_theme(): return "day" def get_x_connection_type(): return "WIFI" def get_x_timestramp(): return str(int(time.time() * 1000)) def get_x_device_model(): return "Redmi M2012K11AC" def get_x_ca_Signature_Headers(): return "X-Ca-Timestamp,X-Ca-Key,X-Ca-Nonce" def get_User_Agent(): return "Mozilla/5.0 (Linux; Android 11; M2012K11AC Build/RQ3A.211001.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/108.0.5359.128 Mobile Safari/537.36 CSDNApp/5.0.0(Android)wToken/0.0.1" def get_x_ca_nonce(): return str(uuid.uuid4()) def get_x_device_id(): return "aid0f0fef992b53479187546b3c621157f0" def get_access_token(): X_Access_Token = "aid0f0fef992b53479187546b3c621157f0AndroidCSDN-APPb85fF96d-7Aa4-4Ec1-bf1D-2133c1A45656" md5_mes = md5(X_Access_Token.encode()) return md5_mes.hexdigest() x_timestramp = get_x_timestramp()x_ca_nonce = get_x_ca_nonce()def get_x_randomnum(): return str(random.randint(10000, 99999)) def get_x_ca_signature(): data = "POST" + "" + \ "application/json" + "" + \ "" + \ "application/json; charset=UTF-8" + "" + \ "" + \ "X-Ca-Key:203789067" + "" + \ "X-Ca-Nonce:3339aae3-e295-410c-8345-52c9ebc56b5a" + "" + \ "X-Ca-Timestamp:1671963564343" + "" + \ "/v1/api/app/login/doLogin" key = "0u94vkvsewic9kkgsp1r3nuq3ir0lv3n".encode("utf-8") message = data.encode("utf-8") sign = base64.b64encode(hmac.new(key, message, digestmod=sha256).digest()) return str(sign, 'utf-8'), x_timestramp, x_ca_nonce def get_xsign(): xsign_mes = get_x_device_id() + get_x_randomnum() + x_timestramp + "F403F982CA92F73AC142D50FFA69853D" return sha1(xsign_mes.encode("utf-8")).hexdigest().upper()
远程调用：
import fridafrom login_env import *import requests def on_message(message, data): print("[%s] => %s" % (message, data)) def inject_hook(): session = frida.get_usb_device().attach('net.csdn.csdnplus') with open('CSDN/rpc.js', 'r') as f: js_code = f.read() script = session.create_script(js_code) script.on('message', on_message) script.load() return script def message(message, data): if message["type"] == 'send': print("[*] {0}".format(message['payload'])) else: print(message) def req(): url = "https://passport.csdn.net/v1/api/app/login/doLogin" headers = { "X-OsVersion": "30", "User-Agent": "Mozilla/5.0 (Linux; Android 11; M2012K11AC Build/RQ3A.211001.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/108.0.5359.128 Mobile Safari/537.36 CSDNApp/5.0.0(Android)wToken/0.0.1", "X-RandomNum": get_x_randomnum(), "X-Access-Token": get_access_token(), "platform": "android", "X-Ca-Signature-Headers": "X-Ca-Timestamp,X-Ca-Key,X-Ca-Nonce", "Authorization": "", "X-OS": "Android", "c_appVersion": "5.0.0", "X-App-ID": "CSDN-APP", "X-App-Theme": "day", "content-type": "application/json; charset=UTF-8", "X-Ca-Signature": get_x_ca_signature()[0], "X-ConnectionType": "WIFI", "UserToken": "", "X-TimeStamp": get_x_ca_signature()[1], "X-Ca-Key": "203789067", "Accept": "application/json", "X-Device-ID": get_x_device_id(), "wToken": res, "X-DeviceModel": "Redmi M2012K11AC", "version": "5.0.0", "X-Ca-Nonce": get_x_ca_signature()[2], "X-Ca-Timestamp": get_x_ca_signature()[1], "X-Sign": get_xsign(), "Host": "passport.csdn.net", "Connection": "Keep-Alive", "Accept-Encoding": "gzip", } data = {"pwdOrVerifyCode":"123456","loginType":"1","userIdentification":"17750659921","checkAli":"true"} response = requests.post(url, headers=headers,json=data) print(response.text) if __name__ == '__main__': rpc_script = inject_hook() res = rpc_script.exports.getwtoken(get_x_ca_signature()[1]) req()'''
结果，校验一致：
{"message":"用户名或密码错误","status":false,"code":"1039"}！
VSole
网络安全专家