# COMPASS SECURITY ADVISORY
# Product: Snom VoIP/SIP Phones (Snom300, Snom320, Snom360,
# Snom370, Snom820)
# Vendor: snom technology AG
# CVD ID: CVE-2009-1048
# Subject: Authentication Bypass of Snom Phone Web Interface
# Risk: High
# Effect: Remote
# Author: Walter Sprenger
# Date: August 13, 2009
The VoIP phones of snom technology AG can be configured, monitored
or controlled with a browser connecting to the built in web interface.
It is strongly recommended to enable authentication on the web
interface and to set a strong password.
By constructing a specially crafted HTTP request the authentication
of the web interface can be completely bypassed.
Access to the web interface without authentication enables a
malicious user to :
- call expensive numbers
- listen to the phone conversation by capturing the network traffic
- read SIP username and password
- read and modify all configuration parameters of the phone
- redirect phone calls to another VoIP server
- activate the microphone and listen to the conversation in the room
- The tests have been conducted on a Snom360, Firmware versions:
- snom360 linux 3.25/snom360-SIP 6.5.17
- snom360 linux 3.25/snom360-SIP 6.5.18
- snom360-SIP 7.1.30
- snom360-SIP 7.1.35 14552
- All Snom300, Snom320, Snom360, Snom370 and Snom820 with firmware versions
below 6.5.20, 7.1.39 and 7.3.14 are vulnerable according to snom technology AG
- Not vulnerable:
- Firmware version 6.5.20 and higher
- Firmware version 7.1.39 and higher
- Firmware version 7.3.14 and higher
The web interface of the Snom VoIP/SIP phones is protected by Basic Authentication
or Digest Authentication.
The authentication can be completely bypassed by modifying the HTTP request.
A normal browser sets the request header "Host:" to the IP address or the host name
that is entered in the URL field of the browser. If the request header is modified
to contain the value "Host: 127.0.0.1", all pages and functions of the web interface
can be reached without prompting the user to authenticate.
How to test:
curl -H "Host: 127.0.0.1" http://<IP address of phone>/
curl -k -H "Host: 127.0.0.1" https://<IP address of phone>/
-> if the phone is vulnerable, the index page of the web interface is returned
-> if the phone is not vulnerable, an "HTTP/1.1 401 Unauthorized" response is returned
Workaround / Fix:
- Upgrade to firmware version 6.5.20, 7.1.39, 7.3.14 or above
- Disable the web interface until a firmware upgrade is installed
Vendor Notified: March 19, 2009
Vendor Status: Replied on March 19 and March 30, vulnerability confirmed
Vendor Response: Problem fixed in firmware version 7.1.39/7.3.14.
Problem will be fixed in version 6.
Patch available: Firmware upgrade to versions 6.5.20, 7.1.39, 7.3.14 and above