Summary

• Certain Cisco Unified IP Conference Station and IP Phone devices contain vulnerabilities which may allow unauthorized users to gain administrative access to vulnerable devices.

  Cisco Unified IP Conference Station Administrative Bypass Vulnerability

  Cisco Unified IP Conference Station 7935 and 7936 devices do not require a password when a URL is accessed directly via the administrator HTTP interface. There is a workaround for this vulnerability.

  Cisco Unified IP Phone Default Account and Privilege Escalation Vulnerabilities

  Cisco Unified IP Phone 7906G, 7911G, 7941G, 7961G, 7970G and 7971G devices contain a hard coded default user account with a default password which is remotely accessible via a Secure Shell (SSH) server enabled on the phone. This default user account may be leveraged to gain administrative access to a vulnerable phone via a privilege escalation vulnerability. The default user account may also execute commands causing a phone to become unstable and result in a denial of service. The default user account can not be disabled, removed or have its password changed. There are mitigations available for these vulnerabilities.

  Cisco has made free software available to address these issues for affected customers.

  This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070221-phone.

Affected Products

• This section provides details on affected products.

  

  Vulnerable Products

  This section provides details on vulnerable products.

  Cisco Unified IP Conference Station

  Model	Affected Firmware Version
  7935	3.2(15) and earlier
  7936	3.3(12) and earlier

  Cisco Unified IP Phone

  Model	Firmware Version
  7906G	8.0(4)SR1 and earlier
  7911G	8.0(4)SR1 and earlier
  7941G	8.0(4)SR1 and earlier
  7961G	8.0(4)SR1 and earlier
  7970G	8.0(4)SR1 and earlier
  7971G	8.0(4)SR1 and earlier

  The version of firmware running on an IP phone can be determined via the Settings menu on a phone.

  In most deployments, Cisco Unified CallManager (CUCM) can also be used to accurately determine the version of firmware that is supposed to be running on an IP phone. While CUCM maintains a record of the firmware it last deployed to an IP phone, it is possible for a user to change the firmware version on an IP phone.

  Products Confirmed Not Vulnerable

  Cisco Unified IP Phone 7902G, 7905, 7905G, 7910, 7912, 7912G, 7920, 7921G, 7940, 7960 and 7985 devices are not vulnerable to the default account and privilege escalation vulnerability.

  No other Cisco products are known to be vulnerable.

Details

• Cisco Unified IP Conference Station 7935 and 7936 devices provide integrated speaker phone services for a networked environment. 7935/7936 devices can be managed via an administrative HTTP interface and/or a with Cisco Unified CallManager (CUCM) system. The administrative HTTP interface is protected by a user configurable password. If a user knows the direct path to a management URL, it may be possible to access the administrative HTTP interface without being prompted for authentication. The vulnerability occurs because vulnerable IP Conference Station devices incorrectly maintain the state of administrator login sessions. If an administrator logs into a vulnerable device via the HTTP interface, the administrator's credentials will be cached even after the administrator logs out of the device. This leaves a window of opportunity for an unauthorized user to gain complete administrative access to a vulnerable device. If an administrator never accesses a potentially vulnerable device via the HTTP interface, the device is not vulnerable to the authentication bypass attack. It is possible to reset to an IP Conference Station to a non-vulnerable state by power-cycling the device or performing a reboot operation (not a reload operation) via the CUCM system which manages the device. This defect is documented in Cisco Bug ID CSCsg26788 ( registered customers only) .

  Cisco Unified IP Phone Default Account and Privilege Escalation Vulnerabilities

  Cisco Unified IP Phone 7906G, 7911G, 7941G, 7961G, 7970G and 7971G devices provide integrated phone service for a networked environment. These IP phones devices contain a hard coded default user account with a default password that is used for debugging purposes and is embedded into the phone's firmware. This default user account cannot be disabled, removed or have its password changed. Due to an implementation error, it possible to use the hard coded default user account to remotely access the Command Line Interface (CLI) of a vulnerable IP phone via a phone's SSH server. The SSH server is only supposed to authenticate user accounts which have been created by an administrator. The SSH server may not be disabled. The firmware update including the solution for this vulnerability prohibits the default user account from accessing a phone via the SSH server, but the default user account may still access the phone via the console serial port. This defect is documented in Cisco Bug ID CSCsg34758 ( registered customers only) .

  Using the default user account to access the CLI of a vulnerable IP phone device (via SSH or the console serial port), an attacker can execute a number of commands which may result in the escalation of privileges leading to complete compromise of an affected IP phone or cause an IP phone to become unstable and crash. These defects are documented in Cisco Bug IDs CSCsg34789 ( registered customers only) and CSCsg42627 ( registered customers only) .

  Vulnerability Scoring Details

  Cisco is providing scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS).

  Cisco will provide a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

  Cisco PSIRT will set the bias in all cases to normal. Customers are encouraged to apply the bias parameter when determining the environmental impact of a particular vulnerability.

  CVSS is a standards based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

  Cisco has provided an FAQ to answer additional questions regarding CVSS at http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html.

  Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at https://sec.cloudapps.cisco.com/security/center/cvssCalculator.x.

  CSCsg26788 - IP Conference Station HTTP Interface Administrator Bypass ( registered customers only )Calculate the environmental score of CSCsg26788
  CVSS Base Score - 10
  Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
  Remote	Low	Not Required	Complete	Complete	Complete	Normal
  CVSS Temporal Score - 8.3
  Exploitability		Remediation Level		Report Confidence
  Functional		Official Fix		Confirmed

  CSCsg34758 - IP Phone SSH Vulnerability ( registered customers only ) Calculate the environmental score of CSCsg34758
  CVSS Base Score - 10
  Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
  Remote	Low	Not Required	Complete	Complete	Complete	Normal
  CVSS Temporal Score - 8.3
  Exploitability		Remediation Level		Report Confidence
  Functional		Official Fix		Confirmed

  CSCsg34789 - Filesystem Privilege Escalation ( registered customers only ) Calculate the environmental score of CSCsg34789
  CVSS Base Score - 6
  Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
  Remote	Low	Required	Complete	Complete	Complete	Normal
  CVSS Temporal Score - 5
  Exploitability		Remediation Level		Report Confidence
  Functional		Official Fix		Confirmed

  CSCsg42627 - Filesystem Denial of Service ( registered customers only ) Calculate the environmental score of CSCsg42627
  CVSS Base Score - 2
  Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
  Remote	Low	Required	None	None	Complete	Normal
  CVSS Temporal Score - 1.7
  Exploitability		Remediation Level		Report Confidence
  Functional		Official Fix		Confirmed

Workarounds

• For Cisco Unified Conference Station and IP Phone devices, the following mitigations have been provided.

  The effectiveness of any mitigation or fix is dependent on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied mitigation or fix is the most appropriate for use in the intended network before it is deployed.

  Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20070221-phone

  Apply access control lists (ACLs) on routers, switches and firewalls that filter traffic to vulnerable Conference Station and IP Phone devices so that traffic is only allowed from stations that need to remotely administer the devices.

  It is possible to workaround the Cisco Unified IP Conference Station Administrative Bypass vulnerability by ensuring that the administrative HTTP interface is not used to manage any vulnerable devices. If the HTTP interface must be used, vulnerable devices should be power cycled or rebooted via a CUCM system after system changes are made.

Fixed Software

• When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

  In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center ("TAC") or your contracted maintenance provider for assistance.

  Cisco Unified IP Conference Station

  Model	Fixed Firmware Version
  7935	3.2(16)
  7936	3.3(13)

  Cisco Unified IP Phone

  Model	Fixed Firmware Version
  7906G	8.0(4)SR2, 8.2(1)
  7911G	8.0(4)SR2, 8.2(1)
  7941G	8.0(4)SR2, 8.2(1)
  7961G	8.0(4)SR2, 8.2(1)
  7970G	8.0(4)SR2, 8.2(1)
  7971G	8.0(4)SR2, 8.2(1)

  Fixed software can be obtained here:

  http://www.cisco.com/pcgi-bin/tablebuild.pl/ip-7900ser

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

  The Conference Station administrative bypass vulnerability was reported to Cisco by Christian Reichert, Christian Blum and Jens Link of Intact Integrated Services.

  The IP Phone default account and privilege escalation vulnerabilities were discovered internally by Cisco.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070221-phone

Revision History

• Revision 1.0

  2007-February-21

  Initial public release

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