Additional technical information is available to describe the Cisco IOS Software Smart Install denial of service vulnerability.
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on vulnerable installations of Cisco IOS.
Cisco devices that have Smart Install client feature enabled in their IOS Software are vulnerable. An unauthenticated, remote attacker could exploit this vulnerability by sending malicious packets to the SMI IBC server. If successful, the attacker could download and replace the configuration and boot-up file of the IOS, create an account with highest user privileges and take complete control of the switch.
Cisco has confirmed this vulnerability and has released updated software.
Cisco has published a list of affected Cisco IOS Software releases in the security advisory. The Vendor Announcements section of this alert contains a link to the advisory.
To exploit this vulnerability, the attacker would need the ability to submit Smart Install packets to the targeted system. To achieve this objective, the attacker may need access to trusted, internal network resources. This access requirement reduces the exposure of this vulnerability.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
An unauthenticated, remote attacker could exploit this vulnerability to completely take over a switch and launch further attacks.
The vulnerability exists in the Smart Install Client as it fails to perform sufficient validation of user-supplied packets.
An unauthenticated, remote attacker could exploit the vulnerability by transmitting a crafted packet to the SMI IBC server to instruct it to download a crafted IOS config file and IOS image file via TCP session to port 4786.
Successful exploitation could allow the attacker to grant access to a user account with elevated privileges as specified in the config file. The attacker could use this access to cause a complete compromise of the affected device.
Administrators are advised to apply the appropriate updates.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Apply hardware rate limiter features to limit packets requiring processing by the device's CPU to mitigate DoS attacks.
Administrators may consider disabling the Smart Install feature.
Administrators are advised to monitor affected systems.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at firstname.lastname@example.org.
Version 1, March 27, 2013, 4:25 PM: Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
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