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看雪论坛作者ID：那年没下雪
某软件charles抓包分析发现跟商品相关的请求头里都带了一个anti-token的字段且每次都不一样，那么下面的操作就从分析anti-token开始了。
1.jadx反编译直接搜索
选中跟http相关的类对这个方法进行打印堆栈。
结合堆栈方法调用的情况找到具体anti-token是由拦截器类f.a方法调用的,在http.a.c()方法中生成并且http.p.e()方法中加入请求头。
在http.a.c()方法中有个一个判断条件如果为true则走d.a().e()方法生成anti-token。
如果为false则走j()方法生成anti-token。
hook这个i()方法返回值可知获取商品详情接口返回值为false所以走的是j()方法进行计算anti-token。
SecureNative.deviceInfo3()方法生成,传入的str为pdd生成的固定id 一个字符串。
根据hook_libart 得到info3()方法是在libodd_secure.so中,那么ida打开看看这个so包。
2.这部分我们采用unidbg+jnitrace+frida相结合的方式
unidbg前期准备的代码这里就不发了直接调用这个info3方法。
这里提示调用gad()方法返回一个字符串那么frida hook这个方法拿到这个值 如下图 一个固定的字符串。
16位长度看着像AES的密钥。
继续补环境 这里简单补环境就不发了。
补完简单的环境代码后,再次运行报这个错误 看错误应该是缺少文件 ,那么看看日志需要补那个文件。
继续运行,没有返回值报空指针。execve()函数执行的时候程序exit了这里我们返回对象本身。
execve()函数执行的时候程序exit了。
execve filename=/system/bin/sh, args=[sh, -c, cat /proc/sys/kernel/random/boot_id]
这个函数相当于查看 boot_id这个文件信息。
捋顺下逻辑应该就是先fork进程 然后在子进程中读取这个文件 然后把他写入pip中。
那么自定义syscallhandler后 再次运行成功拿到结果。
全部代码如下：
package pdd;import com.github.unidbg.AndroidEmulator;import com.github.unidbg.Emulator;import com.github.unidbg.Module;import com.github.unidbg.file.FileResult;import com.github.unidbg.file.IOResolver;import com.github.unidbg.file.linux.AndroidFileIO;import com.github.unidbg.linux.android.AndroidARMEmulator;import com.github.unidbg.linux.android.AndroidEmulatorBuilder;import com.github.unidbg.linux.android.AndroidResolver;import com.github.unidbg.linux.android.dvm.*;import com.github.unidbg.linux.file.ByteArrayFileIO;import com.github.unidbg.memory.Memory;import com.github.unidbg.memory.SvcMemory;import com.github.unidbg.spi.SyscallHandler;import com.github.unidbg.unix.UnixSyscallHandler;import java.io.File;import java.nio.charset.StandardCharsets;import java.util.ArrayList;import java.util.List;import java.util.UUID;public class Pddmain extends AbstractJni implements IOResolver<AndroidFileIO> {private AndroidEmulator androidEmulator;private static final String APK_PATH = "/Users/Downloads/com.xunmeng.pinduoduo_6.7.0_60700.apk";private static final String SO_PATH = "/Users/Downloads/com.xunmeng.pinduoduo_6.7.0_60700/lib/armeabi-v7a/libpdd_secure.so";private Module moduleModule;private VM dalvikVM;public static void main(String[] args) {Pddmain main = new Pddmain();main.create();}private void create() {AndroidEmulatorBuilder androidEmulatorBuilder = new AndroidEmulatorBuilder(false) {public AndroidEmulator build() {return new AndroidARMEmulator("com.xunmeng.pinduoduo",rootDir,backendFactories) {protected UnixSyscallHandler<AndroidFileIO> createSyscallHandler(SvcMemory svcMemory) {return new PddArmSysCallHand(svcMemory);}};}};androidEmulator = androidEmulatorBuilder.setProcessName("").build();androidEmulator.getSyscallHandler().addIOResolver(this);Memory androidEmulatorMemory = androidEmulator.getMemory();androidEmulatorMemory.setLibraryResolver(new AndroidResolver(23));dalvikVM = androidEmulator.createDalvikVM(new File(APK_PATH));DalvikModule module = dalvikVM.loadLibrary(new File(SO_PATH), true);moduleModule = module.getModule();dalvikVM.setJni(this);dalvikVM.setVerbose(true);dalvikVM.callJNI_OnLoad(androidEmulator, moduleModule);callInfo3();}public void callStaticVoidMethodV(BaseVM vm, DvmClass dvmClass, String signature, VaList vaList) {if ("com/tencent/mars/xlog/PLog->i(Ljava/lang/String;Ljava/lang/String;)V".equals(signature)) {return;}super.callStaticVoidMethodV(vm, dvmClass, signature, vaList);}private void callInfo3() {List<Object> argList = new ArrayList<>();argList.add(dalvikVM.getJNIEnv());argList.add(0);DvmObject<?> context = dalvikVM.resolveClass("android/content/Context").newObject(null);argList.add(dalvikVM.addLocalObject(context));argList.add(dalvikVM.addLocalObject(new StringObject(dalvikVM, "api/oak/integration/render")));argList.add(dalvikVM.addLocalObject(new StringObject(dalvikVM, "dIrjGpkC")));Number number = moduleModule.callFunction(androidEmulator, 0xb6f9, argList.toArray())[0];String toString = dalvikVM.getObject(number.intValue()).getValue().toString();System.out.println(toString);}public DvmObject<?> callStaticObjectMethodV(BaseVM vm, DvmClass dvmClass, String signature, VaList vaList) {if ("com/xunmeng/pinduoduo/secure/EU->gad()Ljava/lang/String;".equals(signature)) {return new StringObject(vm, "cb14a9e76b72a627");} else if ("java/util/UUID->randomUUID()Ljava/util/UUID;".equals(signature)) {UUID uuid = UUID.randomUUID();DvmObject<?> dvmObject = vm.resolveClass("java/util/UUID").newObject(uuid);return dvmObject;}return super.callStaticObjectMethodV(vm, dvmClass, signature, vaList);}public DvmObject<?> callObjectMethodV(BaseVM vm, DvmObject<?> dvmObject, String signature, VaList vaList) {if ("java/util/UUID->toString()Ljava/lang/String;".equals(signature)) {UUID uuid = (UUID) dvmObject.getValue();return new StringObject(vm, uuid.toString());} else if ("java/lang/String->replaceAll(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;".equals(signature)) {String obj = dvmObject.getValue().toString();String arg0 = vaList.getObjectArg(0).toString();String arg1 = vaList.getObjectArg(1).toString();String replaceAll = obj.replaceAll(arg0, arg1);return new StringObject(vm, replaceAll);}return super.callObjectMethodV(vm, dvmObject, signature, vaList);}public int callIntMethodV(BaseVM vm, DvmObject<?> dvmObject, String signature, VaList vaList) {if ("java/lang/String->hashCode()I".equals(signature)) {return dvmObject.getValue().toString().hashCode();}return super.callIntMethodV(vm, dvmObject, signature, vaList);}public FileResult<AndroidFileIO> resolve(Emulator<AndroidFileIO> emulator, String pathname, int oflags) {if ("/proc/stat".equals(pathname)) {String info = "cpu 15884810 499865 12934024 24971554 59427 3231204 945931 0 0 0n" +"cpu0 6702550 170428 5497985 19277857 45380 1821584 529454 0 0 0n" +"cpu1 4438333 121907 3285784 1799772 3702 504395 255852 0 0 0n" +"cpu2 2735453 133666 2450712 1812564 4626 538114 93763 0 0 0n" +"cpu3 2008473 73862 1699542 2081360 5716 367109 66860 0 0 0n" +"intr 1022419954 0 0 0 159719900 0 16265892 4846825 5 5 5 6 0 0 497 24817167 17 176595 1352 0 28375276 0 0 0 0 5239 698 0 0 0 0 0 0 3212852 0 12195284 0 0 0 0 0 43 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12513 2743129 375 12477726 0 0 0 0 37 1351794 0 36 8 0 0 0 0 0 0 5846 0 0 0 0 0 0 0 0 0 141 32 0 55 0 0 0 0 0 0 0 0 18 0 18 0 0 0 0 0 0 66 0 0 0 0 0 0 0 77 0 166 0 0 0 0 0 394 0 0 0 0 0 1339137 0 0 0 0 0 0 313 0 0 0 55759 7 7 7 0 0 0 0 0 0 0 0 3066136 0 47 0 0 0 2 2 0 0 0 6 8 0 0 0 2 0 462 2952327 35420 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 495589 0 0 0 0 3 27 0 0 0 0 0 0 0 0 0 0 0 0 0 0 37662 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4760 0 0 97 0 0 0 0 0 0 0 0 0 243 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4649 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22355451 0 0 0 14 0 24449357 96 49415 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 17067 780222 3211 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 649346 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0n" +"ctxt 1572087931n" +"btime 1649910663n" +"processes 230673n" +"procs_running 6n" +"procs_blocked 0n" +"softirq 374327567 12481657 139161248 204829 7276312 2275183 26796 12851725 80988196 1422751 117638870";return FileResult.success(new ByteArrayFileIO(oflags, pathname, info.getBytes(StandardCharsets.UTF_8)));}return null;}}
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原文始发于微信公众号（看雪学苑）：Anti-token保护分析心得
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