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 improper boundary checking and translation of Session Initiation Protocol (SIP) packets by the affected software when it is configured to use network address translation (NAT). An unauthenticated, remote attacker could exploit this vulnerability by sending crafted SIP packets to the affected system. If successful, the attacker could cause the vulnerable device to become unresponsive or could cause it to reload, resulting in a DoS condition.
Cisco has confirmed this 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 improper boundary checking and translation of SIP packets by the affected software when it is configured to use NAT. The processing of transit SIP packets via UDP port 5060 could cause a memory resource exhaustion condition that can lead to a DoS condition.
An unauthenticated, remote attacker could exploit this vulnerability by sending crafted SIP packets to the affected system. If successful, the attacker could cause the vulnerable device to become unresponsive or could cause it to reload, resulting in a DoS condition.
It is likely that an attacker would need to have access to an internal, private network to send crafted SIP requests. This requirement may limit the possibility of a potential attack.
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 allow only privileged users to access administration or management systems.
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 disable the NAT translation of SIP packets feature if this option is not needed with the following command: no ip nat service udp port 5060.
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 email@example.com.
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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.