Exploit the possiblities

Apple setVendorIE Heap Overflow / Information Disclosure

Apple setVendorIE Heap Overflow / Information Disclosure
Posted Sep 22, 2017
Authored by Google Security Research, laginimaineb

Heap overflow and information disclosure vulnerabilities exist in Apple's setVendorIE when handling ioctl results.

tags | advisory, overflow, vulnerability, info disclosure
systems | apple
advisories | CVE-2017-7110
MD5 | 3777e2aae23fd65779213ee09ccc433b

Apple setVendorIE Heap Overflow / Information Disclosure

Change Mirror Download
Apple: Heap overflow and information disclosure in "setVendorIE" when handling ioctl results 


Broadcom produces Wi-Fi HardMAC SoCs which are used to handle the PHY and MAC layer processing. These chips are present in both mobile devices and Wi-Fi routers, and are capable of handling many Wi-Fi related events without delegating to the host OS. On iOS, the "AppleBCMWLANBusInterfacePCIe" driver is used in order to handle the PCIe interface and low-level communication protocols with the Wi-Fi SoC (also referred to as "dongle"). Similarly, the "AppleBCMWLANCore" driver handles the high-level protocols and the Wi-Fi configuration.

Along with the regular flow of frames transferred between the host and the dongle, the two communicate with one another via a set of "ioctls" which can be issued to read or write dongle configuration from the host. This information is exchanged using the "Control Completion" ring, rather than the regular "RX" ring.

When handling certain events such as setting up an access-point, the Wi-Fi chip must be configured to broadcast new information elements for the created network. This is achieved by calling the "setVendorIE" function, which supplies the firmware with a new vendor-specified information element.

Before the information element can be added, the driver must first ensure that no previous IE with the same tag and data has already been configured. This is done by querying the Wi-Fi chip for the current list of Vendor IEs. Each IE's tag and contents are compared to the newly provided IE -- if a match is found, the function issues an additional ioctl to the Wi-Fi chip in order to request that the previous IE be deleted.

The list of IEs returned by the Wi-Fi firmware starts with a 32-bit "count" field, indicating the number of IEs in the list. Each IE is a TLV, where the "tag" and the "length" are both 8-bits fields. Here is a snippet of the approximate high-level code for "setVendorIE":

uint64_t setVendorIE(void* this, void* new_ie) {


//Extracting some information about the new IE
uint8_t* new_ie_buffer = *((uint8_t**)new_ie + 3);
uint32_t new_ie_length = *((uint32_t*)new_ie + 4);
uint8_t new_ie_tag = new_ie_buffer[0];

//Reading the Vendor IE list from the firmware - the IOVar is "vndr_ie"
uint8_t* vendor_ie_list = (uint8_t*)IOMalloc(...);
uint64_t res = issueCommand(..., &vendor_ie_list, ...);

//Searching for a matching IE
uint32_t count = *((uint32_t*)vendor_ie_list);
uint8_t* current_ie = vendor_ie_list + sizeof(uint32_t);
if (count >= 1) {
for (uint32_t i=0; i<count; i++, current_ie += 4) {

//Is this a matching IE?
if (current_ie[8] == new_ie_tag &&
new_ie_length != 1 &&
!bcmp(new_ie + 1, current_ie + 10, new_ie_length-1)) {

//Found a match! Ask the firmware to delete the old IE
void* ie_buffer = IOMalloc(new_ie_length + 13);
strlcpy(ie_buffer, "del", 4);
*(uint32_t*)(ie_buffer + 4) = 1;
ovbcopy(current_ie + 4, ie_buffer + 8, current_ie[9] + 6);
issueCommand(...); //Send the deletion request

As can be seen above, "setVendorIE" fails to verify both the "count" field in the returned IE list, and the length of each individual IE. As a result, an attacker controlling the firmware may choose arbitrarily large values for these fields.

For example, an attacker controlling the firmware could return a list containing an IE with the same tag and payload bytes as the IE being set, but with a large length field (larger than the previous IE's length + 13). Doing so will cause the match above to succeed (as it only compares the contents up to the new IE's length), but will then trigger the "obvcopy" using the attacker-controlled IE length (current_ie[9] + 6), thus overflowing the heap-allocated buffer (ie_buffer).

Alternately, an attacker may choose to supply a large "count" field. Doing so will cause the loop above to read data past the end of the buffer containing the ioctl's results. If, at any point, a sequence of bytes matching the new vendor IE is encountered, the matching conditions above will be satisfied. An attacker can use this as an "oracle" to leak information from the host by spraying sequences containing the vendor IE's contents and slowly incrementing the "count" field. When a match occurs, the driver will issue the deletion ioctl to the firmware, allowing the firmware to deduce that a match occurred at the current offset.

This bug is subject to a 90 day disclosure deadline. After 90 days elapse
or a patch has been made broadly available, the bug report will become
visible to the public.

Found by: laginimaineb


RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

Want To Donate?

Bitcoin: 18PFeCVLwpmaBuQqd5xAYZ8bZdvbyEWMmU

File Archive:

February 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Feb 1st
    15 Files
  • 2
    Feb 2nd
    15 Files
  • 3
    Feb 3rd
    15 Files
  • 4
    Feb 4th
    13 Files
  • 5
    Feb 5th
    16 Files
  • 6
    Feb 6th
    15 Files
  • 7
    Feb 7th
    15 Files
  • 8
    Feb 8th
    15 Files
  • 9
    Feb 9th
    18 Files
  • 10
    Feb 10th
    8 Files
  • 11
    Feb 11th
    8 Files
  • 12
    Feb 12th
    17 Files
  • 13
    Feb 13th
    15 Files
  • 14
    Feb 14th
    15 Files
  • 15
    Feb 15th
    17 Files
  • 16
    Feb 16th
    18 Files
  • 17
    Feb 17th
    37 Files
  • 18
    Feb 18th
    0 Files
  • 19
    Feb 19th
    0 Files
  • 20
    Feb 20th
    0 Files
  • 21
    Feb 21st
    0 Files
  • 22
    Feb 22nd
    0 Files
  • 23
    Feb 23rd
    0 Files
  • 24
    Feb 24th
    0 Files
  • 25
    Feb 25th
    0 Files
  • 26
    Feb 26th
    0 Files
  • 27
    Feb 27th
    0 Files
  • 28
    Feb 28th
    0 Files

Top Authors In Last 30 Days

File Tags


packet storm

© 2018 Packet Storm. All rights reserved.

Security Services
Hosting By