Software Engineering Institute

Huawei E303 wireless broadband modems include a web interface for administration and additional services. The web interface allows users to send and receive SMS messages using the connected cellular network.

CWE-352: Cross-Site Request Forgery (CSRF)
The /api/sms/send-sms URL is vulnerable to cross-site request forgery attacks. The vulnerability can be exploited when a user with adjacent network access to the device visits a malicious webpage. The malicious webpage can silently make requests to the device's SMS API (e.g. http://192.168.1.1/api/sms/send-sms) by leveraging the victim's network access to the device.

Benjamin Daniel Mussler reports:

The Web UI communicates with the vulnerable module by sending and receiving XML requests and responses via XmlHttpRequest, which provides protection against similar attacks. However, the vulnerable module can also be accessed and controlled by sending an HTTP-POST request with XML in the request's body. The vulnerable module will process this XML as if it had originated from the Web UI.

[Proof -of-concept HTTP POST request]:
POST /api/sms/send-sms HTTP/1.1
Host: hi.link
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20100101 Firefox/25.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.8,de-de;q=0.5,de;q=0.3
Accept-Encoding: gzip, deflate
Referer: http://hi.link/
Connection: keep-alive
Content-Type: text/plain
Content-Length: 225

<?xml version="1.0"
encoding="UTF-8"?><request><Index>-1</Index><Phones><Phone>4422</Phone></Phones><Sca></Sca><Content>
Sample Text</Content><Length>0</Length><Reserved>1</Reserved><Date>2013-12-03
16:00:00</Date></request>

The following device configuration was reported to be vulnerable. Other versions may be affected:
Software version: 22.157.18.00.858
Hardware version: CH2E303SM
Web UI version: 11.010.06.01.858

A malicious site could send SMS messages on behalf of the device, possibly incurring SMS charges.

Huawei has stated they are currently working on a fix for this issue. In the meantime, CERT/CC is unaware of a practical solution to this problem.