Some vulnerabilities have been reported in Cisco Unified IP Phone models, which can be exploited by malicious users to compromise a vulnerable device or by malicious people to cause a DoS (Denial of Service) and compromise a vulnerable device.

1) A boundary error within the internal SSH server can be exploited to cause a buffer overflow via a specially crafted packet sent to default port 22/TCP.

2) A boundary error in the parsing of DNS responses can be exploited to cause a buffer overflow.

3) A boundary error in the handling of MIME encoded data can be exploited to cause a buffer overflow via a specially crafted SIP message.

Successful exploitation of the vulnerabilities may allow execution of arbitrary code.

4) A boundary error within the internal telnet server can be exploited to cause a buffer overflow via a specially crafted command.

Successful exploitation may allow execution of arbitrary code but requires that the telnet server is enabled (not enabled by default).

5) A boundary error in the handling of challenge/response messages from an SIP proxy can be exploited to cause a heap-based buffer overflow.

Successful exploitation may allow execution of arbitrary code but requires e.g. control of a SIP proxy.

6) An error in the handling of ICMP echo request packets can be exploited to cause a device to reboot via an overly large ICMP echo request packet.

7) An error within the internal HTTP server when handling HTTP requests can be exploited to cause the device to reboot via a specially crafted HTTP request.

The vulnerabilities affect one or more of the following devices running SCCP and SIP firmwares (please see the vendor's advisory for more information):

Cisco Unified IP Phone devices running SCCP firmware:
* 7906G
* 7911G
* 7935
* 7936
* 7940
* 7940G
* 7941G
* 7960
* 7960G
* 7961G
* 7970G
* 7971G

Cisco Unified IP Phone devices running SIP firmware:
* 7940
* 7940G
* 7960
* 7960G

Solution
Update to the latest firmware versions (see vendor's advisory for details).

Provided and/or discovered by
1) Reported by the vendor
2-5) Jon Griffin and Mustaque Ahamad, School of Computer Science, Georgia Institute of Technology
6) Reported by a Cisco customer
7) Sven Weizenegger, T-Systems

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://www.cisco.com/warp/public/707/cisco-sa-20080213-phone.shtml

Deep Links
Links available to Secunia VIM customers