Android wpa_supplicant WLAN Direct remote buffer overflow

1. Advisory Information

Advisory URL:
http://security.alibaba.com/blog/blog.htm?spm=0.0.0.0.p1ECc3&id=19

Date published: 2015-04-23

Date of last update: 2015-04-23

2. Vulnerability Information

Class: heap overflow

Impact: memory information leak and remote code execution

Remote Exploitable: Yes

Local Exploitable: No

CVE Name: CVE-2015-1863

Vulnerability Information and Patch: http://w1.fi/security/2015-1/

3. Vulnerability Description

In Android, wpa_supplicant is designed to be a "daemon" program that runs in
the background and acts as the backend component controlling the wireless
connection.. When WLAN Direct function of wpa_supplicant is enabled, a
malformed p2p invitation type packet with long ssid can trigger a heap
overflow vulnerability. An attacker could launch a remote attack in the
wireless device signal coverage, access to the victim's android device and
execute native code with the corresponding user privileges (in the android
is wifi user). The user has permission to read the saved WIFI password,
change network configuration, hijacking all Wi-Fi traffic. When combined
with a local privilege escalation vulnerability that allows an attacker to
remotely control a host of victims, implant Trojans and other underlying
implant systems.

4. Vulnerable Packages

         Android 4/Android 5

    wpa_supplicant 2.x

5. Credits

Smart hardware research group of Alibaba security team for discovering the
vulnerability.

6. Technical Description

         wpa_supplicant malloc a p2p_device structure, the oper_ssid field
size of which is 0x20 bytes. In the p2p invitation packet the size of ssid
field is described with an octet, the max of which is 0xff. When copy to
oper_ssid field, the length is not checked. When the size of ssid exceeds
0x20 bytes, it can overflow other fields of the p2p_device structure and
overflow heap structure when exceeds 0x40 bytes.

 

    In the android version 5.1, the source is:

============ p2p_device structure（ wpa_supplicant/p2p/p2p_i.h)============

struct p2p_device {

    [……….]

    int oper_freq;

    u8 oper_ssid[32];  <----- fixed 0x20 bytes 

    size_t oper_ssid_len;

[……….]

    /**

    * go_neg_conf - GO Negotiation Confirmation frame

    */

    struct wpabuf *go_neg_conf;

    int sd_pending_bcast_queries;

};

=========（wpa_supplicant/p2p/p2p.c p2p_add_device ==============

int p2p_add_device(struct p2p_data *p2p, const u8 *addr, int freq,

          struct os_reltime *rx_time, int level, const u8 *ies,

          size_t ies_len, int scan_res)

{

    [……….]

    if (os_memcmp(addr, p2p_dev_addr, ETH_ALEN) != 0)

       os_memcpy(dev->interface_addr, addr, ETH_ALEN);

    if (msg.ssid &&

        (msg.ssid[1] != P2P_WILDCARD_SSID_LEN ||

         os_memcmp(msg.ssid + 2, P2P_WILDCARD_SSID, P2P_WILDCARD_SSID_LEN)

         != 0)) {

        os_memcpy(dev->oper_ssid, msg.ssid + 2, msg.ssid[1]);

//the dest buf is 0x20, but the size is controlled by user input, trigger
buffer overflow 

       dev->oper_ssid_len = msg.ssid[1];

    }

[……….]

7. Vulnerability Impact Assessment：

    1）Affected product：Affect all devices of android version below 5.1 

    2）Default configuration exploitable analysis：Although much of android
devices enable WLAN direct when user enters WLAN Direct UI, but: 

    We found some models of well-known mobile phone manufacturers (such as
Xiaomi, Huawei), default to open the WLAN Direct. Even if the user never
entered the WLAN Direct UI, the attacker can initiate a WLAN direct
connection and trigger this vulnerability without user interaction. However,
an attacker needs to know WLAN Direct MAC address, the address is the MAC
address of user equipment with first byte OR 2, MAC address of the user
equipment can acquire easily by WIFI packet sniffer, so you can calculate
WLAN Direct MAC address, for example the user device MAC address 14: 12: 34:
56: 78: 90, then WLAN Direct MAC address is 16:12 : 34: 56: 78: 90, which
means that some models of mobile phone, simply open the WIFI service, can
suffer from the vulnerability attack.

For other models without WLAN Direct default enabled need to pay attention,
because a lot of file transfer software use WLAN Direct feature and will
enable it. And this feature once enabled, even if the user exits the WLAN
Direct UI, the feature is enabled until the device reboot or WIFI restart.
During this time the device is affected and can be attack remotely.

    3）Impact

    This vulnerability can leak information, use leaked information with ROP
to bypass ASLR and DEP. Exploit this vulnerability successfully, attackers
can execute native code with wifi user permission. Then with wifi user
permission can change wifi configuration and hijack network traffic. 

    And this vulnerability can be exploited remotely, if composite a local
privilege escalation vulnerability, attackers can implant trojan without
physically touch victim devices. 

  So this vulnerability is high risk, especially for wlan direct enabled
default devices. 

8. Poc and Coredump 

    See Advisory URL: http://security.alibaba.com/blog/blog.htm?spm=0.0.0.0.
p1ECc3&id=19

9. Report Timeline

l  2015-4-3：send vulnerability report to android security team

l  2015-4-8：android security team acknowledges the vulnerability and
forward it to wpa_supplicant maintainer

l   2015-4-8：wpa_supplicant maintainer acknowledges

l  2015-4-13：wpa_supplicant maintainer acknowledges timeline for release a
fix

l  2015-4-22：wpa_supplicant maintainer publish the fix and security
advisory

l  2015-4-23：The advisory is published

 


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