XSS Attack using SMS to Optus/Huawei E960 HSDPA Router

Synopsis
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Huawei E960 HSDPA Router (firmware version 246.11.04.11.110sp04) is vulnerable to XSS attack using SMS. One of the feature of this router is the ability to send and receive SMS through its web interface. The SMS text is presented unescaped/unfiltered on the inbox view, and an attacker can craft malicious short messages to gain control over victims router.

Details
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The first 32 characters of every incoming SMS is presented in unescaped form in the inbox view. The 32 characters limit can be overcome by using several messages, and inserting javascript comment to merge the current message with the next one. 

Example:

First message ends with /* which will comment the all the HTML code up to the second message

<script>alert('hello '/*

and the second message will start with */ that will close the comment and continue the script:

*/+'world');</script>

Note that newest message is presented first, so the order of the SMS sending must be reversed.

Impact
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An attacker can 
- get victim's PPP password by accessing /js/connection.js
- disconnect victim's internet connection
- send SMS with victim's router
- gain access to victim's WIFI password

Recovery
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After an attack is performed, the inbox page can not be used to delete the received messages (because the delete button doesn't work anymore). To remove offending messages from the inbox, telnet to the router with username 'admin' and password 'admin'. Huawei E960 uses busybox shell, so standard rm command can be used to remove the messages (it is located at /tmp/sms/inbox_sms). After removing the message content, the deleted messages will still be in the inbox index, but it can now be removed from the inbox page.


Credits
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Rizki Wicaksono (www.ilmuhacking.com) found this vulnerability. The Indonesian article at http://www.ilmuhacking.com/web-security/xss-attack-using-sms-huawei-e960-hsdpa-router/ gives more detail about this vulnerability. This English translation/summary was done by Yohanes Nugroho.