上文通过fiddler抓到了点赞的包,并通过对比不同包的差异确定了需要逆向4个关键字段的算法:X-Ladon、X-Gorgon、X-Tyhon、X-Argus; 本文尝试逆向分析这些字段的实现算法!
逆向都是从数据开始的!于是满怀期待把这4个字符串放到android killer(jdax-gui逆向这种上百兆app时,用全局搜索非常耗内存,我16G的内存都不够用),结果无一例外都找不到!这不是应征了中国人的那句古话:此地无银三百两么!既然这些字段直接搜不到,那么就有这么及种可能:
- 字段本身被分成了好些段,比如X-Ladon被分成了X- La don等段,用完整的字符串搜不到;
- 字段本身被加密了,使用的时候才动态解密,导致静态搜索查不到
- dex文件被加密或加壳导致静态搜索查不到
- X-Ladon是在so层生成的,所以java层静态找不到!在kali下用strings命令查找的结果不乐观,如下:啥都没有
换成X-试试:这次找到了一大堆,但是挨个人肉搜查后发现还是没有我们想要的这4个字段,那么只剩一种可能了:这4个字段都被加密了!
关键字段直接找不到,只能“围魏救赵”,从非关键字段入口;GET头有很多字段,GET的url里面不也有很多字段么?其实这些字段都是为了从客户端给服务端传递信息,没有本质区别的!头的字段不好找,就从url下手呗!用url的“/aweme/v1/commit/item/digg/”下手,终于找到了(而且还只有2处,非常利于查找):
smali代码看着不方便,这里继续换成jadx试试。代码如下:很明显用了retrofit框架!
package com.ss.android.ugc.aweme.feed.api;
import androidx.core.util.Pair;
import com.bytedance.covode.number.Covode;
import com.google.b.h.a.q;
import com.meituan.robust.ChangeQuickRedirect;
import com.meituan.robust.PatchProxy;
import com.meituan.robust.PatchProxyResult;
import com.ss.android.b.a;
import com.ss.android.ugc.aweme.feed.model.DeleteItemResp;
import com.ss.android.ugc.aweme.feed.model.DiggItemResponse;
import com.ss.android.ugc.aweme.services.RetrofitService;
import retrofit2.http.GET;
import retrofit2.http.Query;
public final class FeedActionApi {
/* renamed from: a reason: collision with root package name */
public static ChangeQuickRedirect f167036a;
/* renamed from: b reason: collision with root package name */
public static final RetrofitApi f167037b = ((RetrofitApi) RetrofitService.createIRetrofitServicebyMonsterPlugin(false).createNewRetrofit(a.f123092f).create(RetrofitApi.class));
public interface RetrofitApi {
static {
Covode.recordClassIndex(86951);
}
@GET("/aweme/v1/aweme/delete/")
q<DeleteItemResp> deleteItem(@Query("aweme_id") String str);
@GET("/aweme/v1/commit/item/digg/")
q<DiggItemResponse> diggItem(@Query("aweme_id") String str, @Query("type") int i, @Query("channel_id") int i2, @Query("filter_warn") int i3);
@GET("/aweme/v1/commit/item/digg/")
q<DiggItemResponse> diggItem(@Query("aweme_id") String str, @Query("type") int i, @Query("channel_id") int i2, @Query("city") String str2, @Query("activity") int i3);
@GET("/aweme/v1/commit/item/digg/")
q<DiggItemResponse> diggItem(@Query("aweme_id") String str, @Query("origin_aweme_id") String str2, @Query("type") int i, @Query("channel_id") int i2, @Query("city") String str3, @Query("activity") int i3);
}
static {
Covode.recordClassIndex(86950);
}
public static Pair<String, Integer> a(String str, int i, int i2, String str2) throws Exception {
PatchProxyResult proxy = PatchProxy.proxy(new Object[]{str, Integer.valueOf(i), Integer.valueOf(i2), str2}, null, f167036a, true, 244471);
if (proxy.isSupported) {
return (Pair) proxy.result;
}
f167037b.diggItem(str, i, i2, str2, 0).get();
return Pair.create(str, Integer.valueOf(i));
}
}
从这里也看不出个啥!那就用obejction hook试试呗:结果没任何反应,说明根本没调用!
截至目前,静态分析能用的手段都用了,由于java层混淆地厉害,不太好分析这些类、方法和变量的功能;lib下面的so文件有113个,我也没时间精力挨个拖到IDA去分析,只剩一条路了:内存搜索和dump!
先用objection,查找某个字段,有结果:
用frida查看:意外发现了另一个关键的字符串;
在这个内存地址下断点,一旦有代码读写这个内存地址立即断下来,用来定位关键的代码;andrdoi端该怎么操作了?先试试GameGardiance!尝试后发现这里只能查找字符串地址,然后根据maps映射查看,发现这些地址都是通过malloc函数在栈上分配的,根本不再代码段(这又是一句正确的废话),无法定位到具体的so!
X-Ladon也是:都是通过malloc在栈上分配的地址,无法定位到so文件!
换成最熟悉的CE:X-Ladon关键字段存放的位置很多,但是值得关注的不超过5个,如下:
本以为胜利就在眼前,想直接通过“find out what access this address”定位到关键代码,结果直接报错!what the fxxk.............
刚开始不知道为啥,后来查了很多资料,发现是hw手机即使root后,默认也没开启硬件断点,所以用gdb调试也没法下硬件断点:
先根据ce的地址找X-Ladon字段,结果在这个字段的附近居然同时出现了其他3个字段,真是得来全不费功夫啊)!
耐心点:每个字段都下个读写断点:
有可能是这些通过malloc分配的地址只用1次(尝试过用pixel,毕竟是Google的亲儿子,root后默认是开启了硬件断点的。用CE的“find out what access this address”还是没断下来;不管我更换多少视频、点赞等操作,通过CE查看内存数据一直都没变,说明这块内存只被用了一次就没再用了; 后续从sub_6221c函数分析得知: 这3个字段每次生成前都用malloc分配内存,所以这些内存只用一次,用内存断点的方式自然是找不到读写的代码),用完就回收,所以导致断不下来!这种方式每次用的时候都要申请内存,效率较低,但也更加安全,可以有效防止内存断点的追踪!还有一种可能:这些加密字段是针对当时发送的数据做加密的,因为每次发送的数据包不同,所以每个数据包加密的密文只用1次,所以用这种方式是无效的!好吧,思路到这里又断了!
换个思路:从/proc/pid/maps这里看到,这些地址内存都是通过libc的malloc函数分配的内存,要是在这里下断点,然后在栈上回溯,是不是就能追踪到调用者了?
frida有个trace的功能(ida也有,但是调试时经常弹窗爆各种异常,需要手动选择和点击,trace的效率台低,已经放弃),首次运行命令后会生成一个js脚本,然后自己在js脚本添加需要打印的信息,我改后的js脚本如下:
{
/**
* Called synchronously when about to call malloc.
*
* @this {object} - Object allowing you to store state for use in onLeave.
* @param {function} log - Call this function with a string to be presented to the user.
* @param {array} args - Function arguments represented as an array of NativePointer objects.
* For example use args[0].readUtf8String() if the first argument is a pointer to a C string encoded as UTF-8.
* It is also possible to modify arguments by assigning a NativePointer object to an element of this array.
* @param {object} state - Object allowing you to keep state across function calls.
* Only one JavaScript function will execute at a time, so do not worry about race-conditions.
* However, do not use this to store function arguments across onEnter/onLeave, but instead
* use "this" which is an object for keeping state local to an invocation.
*/
onEnter(log, args, state) {
log('malloc()');
log('RegisterNatives called from:\n' +Thread.backtrace(this.context, Backtracer.ACCURATE).map(DebugSymbol.fromAddress).join('\n') + '\n');
},
/**
* Called synchronously when about to return from malloc.
*
* See onEnter for details.
*
* @this {object} - Object allowing you to access state stored in onEnter.
* @param {function} log - Call this function with a string to be presented to the user.
* @param {NativePointer} retval - Return value represented as a NativePointer object.
* @param {object} state - Object allowing you to keep state across function calls.
*/
onLeave(log, retval, state) {
}
}
这里打印调用堆栈;由于被调用很多次,我就不把所有的日子都贴出来了,这里选几个比较关键的:
/* TID 0x30d7 (想不到x音也用sqlite)*/
9939 ms RegisterNatives called from:
0xf6f9347d libsqlite.so!0x1e47d
0xf6f8761d libsqlite.so!0x1261d
0xf6f835a5 libsqlite.so!0xe5a5
0xf6f8c939 libsqlite.so!0x17939
0xf6fa2e7d libsqlite.so!0x2de7d
0xf6faf1c1 libsqlite.so!0x3a1c1
0xf6fb24ef libsqlite.so!sqlite3_step+0x19e
0xf757d289 libandroid_runtime.so!0x6b289
0x7343c281 system@framework@boot.oat!oatexec+0x9e5281
10513 ms malloc()
/* TID 0x3c57 */
10490 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7649a45 libutils.so!_ZN7android10VectorImpl5_growEjj+0x78
0xf7649b41 libutils.so!_ZN7android10VectorImpl8insertAtEPKvjj+0x18
0xf735d803 libui.so!_ZN7android6RegionC2Ev+0x2a
0xf733af79 libgui.so!_ZN7android7Surface11queueBufferEP19ANativeWindowBufferi+0x174
0xf63af4f5 libstagefright.so!_ZN7android6ACodec9BaseState21onOutputBufferDrainedERKNS_2spINS_8AMessageEEE+0x1fc
0xf63ae091 libstagefright.so!_ZN7android6ACodec9BaseState17onMessageReceivedERKNS_2spINS_8AMessageEEE+0x27c
0xf63b166b libstagefright.so!_ZN7android6ACodec14ExecutingState17onMessageReceivedERKNS_2spINS_8AMessageEEE+0x1ea
0xf632a503 libstagefright_foundation.so!_ZN7android25AHierarchicalStateMachine13handleMessageERKNS_2spINS_8AMessageEEE+0x42
0xf632a367 libstagefright_foundation.so!_ZN7android8AHandler14deliverMessageERKNS_2spINS_8AMessageEEE+0x12
0xf632c43b libstagefright_foundation.so!_ZN7android8AMessage7deliverEv+0x3a
0xf632ad8d libstagefright_foundation.so!_ZN7android7ALooper4loopEv+0xe4
0xf7648b67 libutils.so!_ZN7android6Thread11_threadLoopEPv+0x72
0xf742c7bd libc.so!_ZL15__pthread_startPv+0x20
0xf74042d7 libc.so!__start_thread+0x8
/* TID 0x2eba */
10206 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7649c45 libutils.so!_ZN7android10VectorImpl7_shrinkEjj+0x58
0xf7649ce5 libutils.so!_ZN7android10VectorImpl13removeItemsAtEjj+0x10
0xf72ee91f libinput.so!_ZN7android13InputConsumer7consumeEPNS_26InputEventFactoryInterfaceEbxPjPPNS_10InputEventE+0x156
0xf75801e1 libandroid_runtime.so!_ZN7android24NativeInputEventReceiver13consumeEventsEP7_JNIEnvbxPb+0x64
0xf75803dd libandroid_runtime.so!_ZN7android24NativeInputEventReceiver11handleEventEiiPv+0x34
0xf764b9d1 libutils.so!_ZN7android6Looper9pollInnerEi+0x214
0xf764baa3 libutils.so!_ZN7android6Looper8pollOnceEiPiS1_PPv+0x86
0xf7589e0d libandroid_runtime.so!_ZN7android18NativeMessageQueue8pollOnceEP7_JNIEnvP8_jobjecti+0x1a
0x72a5755f system@framework@boot.oat!oatexec+0x55f
10583 ms malloc()
/* TID 0x3c56 */
10510 ms RegisterNatives called from:
0xf749c5ad libc++.so!_Znwj+0x14
0xb9647870
/* TID 0x2eba */
10583 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7649c45 libutils.so!_ZN7android10VectorImpl7_shrinkEjj+0x58
0xf72e8fc5 libinput.so!_ZN7android11MotionEvent10initializeEiiiiiiiiffffxxjPKNS_17PointerPropertiesEPKNS_13PointerCoordsE+0x8a
0xf72ee573 libinput.so!_ZN7android13InputConsumer21initializeMotionEventEPNS_11MotionEventEPKNS_12InputMessageE+0xa0
0xf72ee927 libinput.so!_ZN7android13InputConsumer7consumeEPNS_26InputEventFactoryInterfaceEbxPjPPNS_10InputEventE+0x15e
0xf75801e1 libandroid_runtime.so!_ZN7android24NativeInputEventReceiver13consumeEventsEP7_JNIEnvbxPb+0x64
0xf75803dd libandroid_runtime.so!_ZN7android24NativeInputEventReceiver11handleEventEiiPv+0x34
0xf764b9d1 libutils.so!_ZN7android6Looper9pollInnerEi+0x214
0xf764baa3 libutils.so!_ZN7android6Looper8pollOnceEiPiS1_PPv+0x86
0xf7589e0d libandroid_runtime.so!_ZN7android18NativeMessageQueue8pollOnceEP7_JNIEnvP8_jobjecti+0x1a
0x72a5755f system@framework@boot.oat!oatexec+0x55f
/* TID 0x3c57 */
10539 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7649a45 libutils.so!_ZN7android10VectorImpl5_growEjj+0x78
0xf7649b41 libutils.so!_ZN7android10VectorImpl8insertAtEPKvjj+0x18
0xf735d803 libui.so!_ZN7android6RegionC2Ev+0x2a
0xf7324275 libgui.so!_ZN7android10BufferItemC1Ev+0x40
0xf7329adb libgui.so!_ZN7android19BufferQueueProducer11queueBufferEiRKNS_22IGraphicBufferProducer16QueueBufferInputEPNS1_17QueueBufferOutputE+0x172
0xf733aff3 libgui.so!_ZN7android7Surface11queueBufferEP19ANativeWindowBufferi+0x1ee
0xf63af4f5 libstagefright.so!_ZN7android6ACodec9BaseState21onOutputBufferDrainedERKNS_2spINS_8AMessageEEE+0x1fc
0xf63ae091 libstagefright.so!_ZN7android6ACodec9BaseState17onMessageReceivedERKNS_2spINS_8AMessageEEE+0x27c
0xf63b166b libstagefright.so!_ZN7android6ACodec14ExecutingState17onMessageReceivedERKNS_2spINS_8AMessageEEE+0x1ea
0xf632a503 libstagefright_foundation.so!_ZN7android25AHierarchicalStateMachine13handleMessageERKNS_2spINS_8AMessageEEE+0x42
0xf632a367 libstagefright_foundation.so!_ZN7android8AHandler14deliverMessageERKNS_2spINS_8AMessageEEE+0x12
0xf632c43b libstagefright_foundation.so!_ZN7android8AMessage7deliverEv+0x3a
0xf632ad8d libstagefright_foundation.so!_ZN7android7ALooper4loopEv+0xe4
0xf7648b67 libutils.so!_ZN7android6Thread11_threadLoopEPv+0x72
0xf742c7bd libc.so!_ZL15__pthread_startPv+0x20
10722 ms malloc()
/* TID 0x2eba */
10598 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf764749b libutils.so!_ZNK7android12SharedBuffer10editResizeEj+0x2e
0xf7649c33 libutils.so!_ZN7android10VectorImpl7_shrinkEjj+0x46
0xf72e8fd7 libinput.so!_ZN7android11MotionEvent10initializeEiiiiiiiiffffxxjPKNS_17PointerPropertiesEPKNS_13PointerCoordsE+0x9c
0xf72ee573 libinput.so!_ZN7android13InputConsumer21initializeMotionEventEPNS_11MotionEventEPKNS_12InputMessageE+0xa0
0xf72ee927 libinput.so!_ZN7android13InputConsumer7consumeEPNS_26InputEventFactoryInterfaceEbxPjPPNS_10InputEventE+0x15e
0xf75801e1 libandroid_runtime.so!_ZN7android24NativeInputEventReceiver13consumeEventsEP7_JNIEnvbxPb+0x64
0xf75803dd libandroid_runtime.so!_ZN7android24NativeInputEventReceiver11handleEventEiiPv+0x34
0xf764b9d1 libutils.so!_ZN7android6Looper9pollInnerEi+0x214
0xf764baa3 libutils.so!_ZN7android6Looper8pollOnceEiPiS1_PPv+0x86
0xf7589e0d libandroid_runtime.so!_ZN7android18NativeMessageQueue8pollOnceEP7_JNIEnvP8_jobjecti+0x1a
0x72a5755f system@framework@boot.oat!oatexec+0x55f
10748 ms malloc()
10748 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7649c45 libutils.so!_ZN7android10VectorImpl7_shrinkEjj+0x58
0xf72e8fdf libinput.so!_ZN7android11MotionEvent10initializeEiiiiiiiiffffxxjPKNS_17PointerPropertiesEPKNS_13PointerCoordsE+0xa4
0xf72ee573 libinput.so!_ZN7android13InputConsumer21initializeMotionEventEPNS_11MotionEventEPKNS_12InputMessageE+0xa0
0xf72ee927 libinput.so!_ZN7android13InputConsumer7consumeEPNS_26InputEventFactoryInterfaceEbxPjPPNS_10InputEventE+0x15e
0xf75801e1 libandroid_runtime.so!_ZN7android24NativeInputEventReceiver13consumeEventsEP7_JNIEnvbxPb+0x64
0xf75803dd libandroid_runtime.so!_ZN7android24NativeInputEventReceiver11handleEventEiiPv+0x34
0xf764b9d1 libutils.so!_ZN7android6Looper9pollInnerEi+0x214
0xf764baa3 libutils.so!_ZN7android6Looper8pollOnceEiPiS1_PPv+0x86
0xf7589e0d libandroid_runtime.so!_ZN7android18NativeMessageQueue8pollOnceEP7_JNIEnvP8_jobjecti+0x1a
0x72a5755f system@framework@boot.oat!oatexec+0x55f
10852 ms malloc()
/* TID 0x2f52 */
10513 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7648017 libutils.so!_ZN7android8String16C1EPKDsj+0x10
0xf761e20d libbinder.so!_ZNK7android6Parcel12readString16Ev+0x18
0xf761e269 libbinder.so!_ZNK7android6Parcel16enforceInterfaceERKNS_8String16EPNS_14IPCThreadStateE+0x38
0xf6acb9f9 libmedia.so!_ZN7android13BnOMXObserver10onTransactEjRKNS_6ParcelEPS1_j+0x20
0xf76148f3 libbinder.so!_ZN7android7BBinder8transactEjRKNS_6ParcelEPS1_j+0x3e
0xf7619c8d libbinder.so!_ZN7android14IPCThreadState14executeCommandEi+0x228
0xf7619df9 libbinder.so!_ZN7android14IPCThreadState20getAndExecuteCommandEv+0x44
0xf7619e5d libbinder.so!_ZN7android14IPCThreadState14joinThreadPoolEb+0x34
0xf761e8c1 libbinder.so!0x1f8c1
0xf7648b67 libutils.so!_ZN7android6Thread11_threadLoopEPv+0x72
0xf7566525 libandroid_runtime.so!_ZN7android14AndroidRuntime15javaThreadShellEPv+0x48
0xf742c7bd libc.so!_ZL15__pthread_startPv+0x20
0xf74042d7 libc.so!__start_thread+0x8
11018 ms malloc()
11018 ms RegisterNatives called from:
0xf749c5ad libc++.so!_Znwj+0x14
0xa895f290
/* TID 0x2eba */
10951 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf7649c45 libutils.so!_ZN7android10VectorImpl7_shrinkEjj+0x58
0xf72e8fc5 libinput.so!_ZN7android11MotionEvent10initializeEiiiiiiiiffffxxjPKNS_17PointerPropertiesEPKNS_13PointerCoordsE+0x8a
0xf72ee573 libinput.so!_ZN7android13InputConsumer21initializeMotionEventEPNS_11MotionEventEPKNS_12InputMessageE+0xa0
0xf72ee927 libinput.so!_ZN7android13InputConsumer7consumeEPNS_26InputEventFactoryInterfaceEbxPjPPNS_10InputEventE+0x15e
0xf75801e1 libandroid_runtime.so!_ZN7android24NativeInputEventReceiver13consumeEventsEP7_JNIEnvbxPb+0x64
0xf75803dd libandroid_runtime.so!_ZN7android24NativeInputEventReceiver11handleEventEiiPv+0x34
0xf764b9d1 libutils.so!_ZN7android6Looper9pollInnerEi+0x214
0xf764baa3 libutils.so!_ZN7android6Looper8pollOnceEiPiS1_PPv+0x86
0xf7589e0d libandroid_runtime.so!_ZN7android18NativeMessageQueue8pollOnceEP7_JNIEnvP8_jobjecti+0x1a
0x72a5755f system@framework@boot.oat!oatexec+0x55f
11020 ms malloc()
11020 ms RegisterNatives called from:
0xf76473c1 libutils.so!_ZN7android12SharedBuffer5allocEj+0x20
0xf764749b libutils.so!_ZNK7android12SharedBuffer10editResizeEj+0x2e
0xf7649c33 libutils.so!_ZN7android10VectorImpl7_shrinkEjj+0x46
0xf72e8fd7 libinput.so!_ZN7android11MotionEvent10initializeEiiiiiiiiffffxxjPKNS_17PointerPropertiesEPKNS_13PointerCoordsE+0x9c
0xf72ee573 libinput.so!_ZN7android13InputConsumer21initializeMotionEventEPNS_11MotionEventEPKNS_12InputMessageE+0xa0
0xf72ee927 libinput.so!_ZN7android13InputConsumer7consumeEPNS_26InputEventFactoryInterfaceEbxPjPPNS_10InputEventE+0x15e
0xf75801e1 libandroid_runtime.so!_ZN7android24NativeInputEventReceiver13consumeEventsEP7_JNIEnvbxPb+0x64
0xf75803dd libandroid_runtime.so!_ZN7android24NativeInputEventReceiver11handleEventEiiPv+0x34
0xf764b9d1 libutils.so!_ZN7android6Looper9pollInnerEi+0x214
0xf764baa3 libutils.so!_ZN7android6Looper8pollOnceEiPiS1_PPv+0x86
0xf7589e0d libandroid_runtime.so!_ZN7android18NativeMessageQueue8pollOnceEP7_JNIEnvP8_jobjecti+0x1a
0x72a5755f system@framework@boot.oat!oatexec+0x55f
从日志来看,调用libc.so文件中malloc函数的so文件不多,有libutils.so、libinput.so、libc++.so、libbinder.so、libstagefright.so、libui.so、libgui.so、libsqlite.so,这些so的数量和原始110多个so比,范围已经小了很多;并且也能定位到so的哪一行代码层层调用了malloc函数,后续先从内存dump这些so,从这里开始继续分析!
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个人猜测是给公司内部所有产品使用的通用代码);这些基础框架代码包含了retrofit代码,通过http、network等关键自研,hook了 “com.bytedance.frameworks.baselib.network.http.util.UrlUtils.encode” 这个函数;又根据调用栈找到了com.ss.android.ugc.aweme.bp.d$3$1.run,这个是栈底的函数了,说明就是从这里开始运行的;并且从命名看,这明显是x音的函数,所以需要重点跟踪!从java层的源码看,这个是Thread线程,当试图搜索这个函数的start方法时,但是根本找不到(如下):猜测start方法可能被加壳隐藏了,后续还要好好找找在哪藏着的!