Software Engineering Institute

To exploit this vulnerability, the IOS HTTP interface must be enabled and the attacker must transmit a request for "http://router-ip/anytext?/". Upon sending the request, the attacker will be asked for the device's "enable" password. If the password prompt is successfully answered, the software becomes trapped in a loop until a two-minute watchdog timer expires, causing the device to restart.

An attacker can force affected products to reboot, resulting in a denial-of-service while the device is restarting. In some situations, the device may not restart properly without manual intervention such as a power cycle.

Apply a patch from Cisco

Cisco has provided patches for affected versions of the IOS software. For further details, please consult the vendor section of this document.

Choose appropriate passwords

To exploit this vulnerability, an attacker must know the enable password for the affected router or switch. Therefore, devices with either an easily guessable password or no password at all are particularly vulnerable. For further information on choosing appropriate passwords, please consult the CERT Security Practice, "Configure computers for user authentication."

Disable the HTTP management interface

If it is not possible or practical to immediately patch an affected device, disable its HTTP management interface to prevent exploitation of this vulnerability.

Restrict access to the HTTP management interface

If it is not possible to disable the HTTP management interface, users should restrict outside networks from accessing it. For information on how to implement these restrictions, please consult the Cisco advisory at

http://www.cisco.com/warp/public/707/ioshttpserverquery-pub.shtml