what you don't know can hurt you

Apple WLC_E_COUNTRY_CODE_CHANGED Information Leak

Apple WLC_E_COUNTRY_CODE_CHANGED Information Leak
Posted Sep 22, 2017
Authored by Google Security Research, laginimaineb

Apple products suffers from an information leak when handling WLC_E_COUNTRY_CODE_CHANGED event packets.

tags | advisory
systems | apple
advisories | CVE-2017-7116
MD5 | 18dfa8691803d310aeb0e9d26cfe8d89

Apple WLC_E_COUNTRY_CODE_CHANGED Information Leak

Change Mirror Download
Apple: Information Leak when handling WLC_E_COUNTRY_CODE_CHANGED event packets 

CVE-2017-7116


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.

When the dongle wishes to notify the host OS of an event, it does so by encoding a special "packet" and transmitting it to the host. These packets have an ether type of 0x886C, and do not contain actual packet data, but rather encapsulate information about events which must be handled by the driver.

One of the supported event packets is the WLC_E_COUNTRY_CODE_CHANGED message, which notifies that host that the country code has been modified. On iOS, these events are handled by the "handleCountryCodeChangedEvent" function in the "AppleBCMWLANCore" driver. Each packet of this type starts with the common event message header (which is 48 bytes long), followed by the 3-character country code, delimited by a NUL.

Here is a snippet of "handleCountryCodeChangedEvent"'s high-level logic:

int64_t handleCountryCodeChangedEvent(void* this, uint8_t* event_packet) {

char* country_code = (char*)this + 3244;
char* alt_country_code = (char*)this + 3248;
strncpy(country_code, event_packet + 48, 3);
country_code[3] = '\0';

if ( strncmp(country_code, "XZ", strlen("XZ")) &&
strncmp(alt_country_code, country_code 4)) {

strncpy(alt_country_code, country_code, 3);
alt_country_code[3] = '\0';
updateChannelSpecsAsync(this);

}
...
}

int64_t updateChannelSpecsAsync(void* this)
{
char request_buffer[0x1C2];
bzero(request_buffer, 0x1C2);
char* country_code = (char*)this + 3244;
strlcpy(request_buffer, country_code, 4);
return issueCommand(..., request_buffer, ...); //Getting the "chanspecs" IO-Var
...
}

As can be seen above, the function fails to verify that the length of the event message is sufficiently long (that is, larger than just the message header itself). As a result, an attacker controlling the dongle can send a WLC_E_COUNTRY_CODE_CHANGED event packet with no body payload. Doing so will cause the 3 bytes of the country code to be copied OOB (from event_packet + 48). As long as these bytes are not "XZ" or the previously stored country code ("alt_country_code"), "updateChannelSpecsAsync" will be called, causing the OOB data to be sent back to the dongle in the WLC_GET_VAR ioctl - thus leaking the bytes back to the dongle.

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

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

File Archive:

May 2019

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    May 1st
    16 Files
  • 2
    May 2nd
    8 Files
  • 3
    May 3rd
    8 Files
  • 4
    May 4th
    2 Files
  • 5
    May 5th
    1 Files
  • 6
    May 6th
    15 Files
  • 7
    May 7th
    22 Files
  • 8
    May 8th
    16 Files
  • 9
    May 9th
    17 Files
  • 10
    May 10th
    16 Files
  • 11
    May 11th
    3 Files
  • 12
    May 12th
    4 Files
  • 13
    May 13th
    25 Files
  • 14
    May 14th
    24 Files
  • 15
    May 15th
    78 Files
  • 16
    May 16th
    16 Files
  • 17
    May 17th
    12 Files
  • 18
    May 18th
    2 Files
  • 19
    May 19th
    1 Files
  • 20
    May 20th
    2 Files
  • 21
    May 21st
    0 Files
  • 22
    May 22nd
    0 Files
  • 23
    May 23rd
    0 Files
  • 24
    May 24th
    0 Files
  • 25
    May 25th
    0 Files
  • 26
    May 26th
    0 Files
  • 27
    May 27th
    0 Files
  • 28
    May 28th
    0 Files
  • 29
    May 29th
    0 Files
  • 30
    May 30th
    0 Files
  • 31
    May 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2019 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close