Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
Description
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is in the affected device when it handles crafted H.323 packets. An unauthenticated, remote attacker could exploit this vulnerability by sending crafted H.323 packets to the affected system. When the device tries to process these packets, an unspecified error could occur that could cause the device to reload, resulting in a DoS condition.
Cisco has confirmed this vulnerability and released updated software.
Warning Indicators
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.
IntelliShield Analysis
Only devices that are configured to process H.323 messages are vulnerable. H.323 message processing is disabled by default. Details on how to determine if this feature has been enabled are in the vendor advisory.
Exploitation requires the attacker to complete a three-way TCP handshake. For this reason the attacker will not be able to spoof the source address of the malicious H.323 packets.
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 cause a DoS condition on the affected device. Repeated attacks could result in a persistent DoS condition.
Technical Information
The vulnerability is in the H.323 processing component of the affected systems when it handles crafted H.323 packets. An unauthenticated, remote attacker could exploit this vulnerability by sending a series of crafted H.323 packets to the affected system on TCP port 1720. When the system tries to process these packets, it may reload, resulting in a DoS condition.
Safeguards
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 on TCP port 1720.
The Cisco Applied Intelligence team has created the following companion document to guide administrators in identifying and mitigating attempts to exploit this vulnerability prior to applying updated software: cisco-amb-20090923-voice
Patches/Software
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 tac@cisco.com.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
The security vulnerability applies to the following combinations of products.
Primary Products:
Cisco
IOS
12.2B Base | 12.2BX Base | 12.2CZ Base | 12.2MC Base | 12.2T Base | 12.2XNB Base | 12.2XNC Base | 12.2YH Base | 12.2YJ Base | 12.2YL Base | 12.2YM Base | 12.2YN Base | 12.2YT Base | 12.2YU Base | 12.2YV Base | 12.2ZC Base | 12.2ZD Base | 12.2ZE Base | 12.2ZF Base | 12.2ZH Base | 12.2ZJ Base | 12.2ZL Base | 12.2ZP Base | 12.3 Base, T | 12.3B Base | 12.3JK Base | 12.3T Base | 12.3TPC Base | 12.3VA Base | 12.3XA Base | 12.3XB Base | 12.3XC Base | 12.3XD Base | 12.3XE Base | 12.3XF Base | 12.3XG Base | 12.3XI Base | 12.3XJ Base | 12.3XK Base | 12.3XL Base | 12.3XQ Base | 12.3XR Base | 12.3XU Base | 12.3XW Base | 12.3XX Base | 12.3XY Base | 12.3XZ Base | 12.3YF Base | 12.3YG Base | 12.3YK Base | 12.3YM Base | 12.3YQ Base | 12.3YS Base | 12.3YT Base | 12.3YU Base | 12.3YX Base | 12.3YZ Base | 12.3ZA Base | 12.4 Base | 12.4MR Base | 12.4T Base | 12.4XA Base | 12.4XB Base | 12.4XC Base | 12.4XD Base | 12.4XE Base | 12.4XJ Base | 12.4XL Base | 12.4XM Base | 12.4XP Base | 12.4XT Base | 12.4XV Base | 12.4XW Base | 12.4XY Base | 12.4XZ Base | 12.4YA Base | 12.4YB Base
Associated Products:
N/A
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