Cisco has re-released a security advisory and updated software to address the NX-OS software malformed IP packet denial of service vulnerability.
Cisco NX-OS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is in the IP stack of the affected software and any feature that uses services offered by the IP stack to parse IP packets. The vulnerability occurs when the affected software attempts to obtain Layer 4 information of a malformed IP packet. An unauthenticated, remote attacker could exploit this vulnerability by sending malformed IP packets through the targeted device. If successful, the attacker could cause the device to stop responding, resulting in a DoS condition.
Cisco has confirmed this vulnerability in a security advisory and software updates are available.
The following versions of Cisco Nexus Series Switches are vulnerable when they are running affected versions of Cisco NX-OS Software. The Vendor Announcements section of this alert contains a link to the advisory.
Cisco Nexus 1000v Series Switches
Cisco Nexus 1010 Series Switches
Cisco Nexus 5000 Series Switches
Cisco Nexus 7000 Series Switches
Cisco VSG for Nexus 1000V Series Switches
A successful exploit could allow an attacker to cause a device to stop responding, potentially preventing authorized users from accessing network resources served by the targeted device.
A successful exploit does not affect all Cisco Nexus products. Affected products are identified in the "Warning Indicators" section of this alert.
This alert contains CVSS scoring supplied by Cisco, the primary vendor of the affected product. 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 targeted device to stop responding, resulting in a DoS condition.
The vulnerability is in the operating system's IP stack and any feature that uses services offered by the IP stack to parse IP packets is affected. The vulnerability occurs when the affected software attempts to obtain Layer 4 information of a malformed IP packet, causing the netstack process to terminate unexpectedly and resulting in a DoS condition.
Only transit traffic may trigger the vulnerability; malformed IP packets destined to the device running the affected software do not trigger this vulnerability. Additionally, the vulnerability can be triggered by UDP or TCP connections.
An unauthenticated, remote attacker could exploit this vulnerability by sending malformed IP packets through the targeted device. When processed, the malformed IP packets could cause the device to stop responding, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
Administrators are advised to monitor critical 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 15, 2012, 11:41 AM: Cisco NX-OS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
The security vulnerability applies to the following combinations of products.
Cisco Virtual Security Gateway for Nexus 1000V Series Switches
4.2(1) VSG1(1), VSG1(2)
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