Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability is due to the improper processing of crafted IP packets by the affected software when it is configured with the zone-based firewall feature. An unauthenticated, remote attacker could exploit this vulnerability by sending specially crafted IP packets to a vulnerable device. If successful, the attacker could cause the device to reload, resulting in a DoS condition.
Cisco has confirmed the vulnerability in a security advisory and released updated software.
Indicators of Compromise
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.
The vulnerability is due to the improper processing of crafted IP packets by the affected software when it is configured with the zone-based firewall feature. The vulnerability can be triggered only by traffic destined to an IP address configured on the device; traffic in transit through the vulnerable device is not an exploit vector.
An unauthenticated, remote attacker could exploit this vulnerability by sending specially crafted IP packets to a vulnerable device. If successful, the attacker could cause the device to reload or trigger memory leaks that may result in system instabilities, resulting in a DoS condition. Repeated attacks could result in a sustained DoS condition on the affected device.
A successful exploit could allow an attacker to cause the vulnerable device to reload or stop responding, potentially preventing authorized users from accessing network resources served by the targeted device.
It is likely that the vulnerable device is behind a firewall that is between a public and private network. As a result, an attacker would need to have access to an internal network to send crafted IP packets to a vulnerable device. This requirement could limit the possibility for an attack.
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.
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 may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
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.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.