Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to insufficient validation of TCP connection information when a vulnerable protocol translation configuration in the affected software is in use. An attacker could exploit this vulnerability by trying to connect to the affected protocol translation resource on the affected device. An exploit could allow the attacker to cause a reload of the affected device.
Cisco confirmed the vulnerability in a security advisory and released updated software.
Indicators of Compromise
Cisco devices running an affected version of Cisco IOS Software and have either a vulnerable protocol translation configuration or a Telnet-to-PAD protocol translation ruleset configured are affected.
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 insufficient validation of TCP connection information when the protocol translation feature is used by the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by trying to connect to the affected protocol translation resource on the affected device. Successful exploitation could allow the attacker to cause a reload of the affected device, resulting in a DoS condition.
It is likely that an attacker would need to have access to an internal, private network behind a firewall in order to connect to the affected translation feature on the affected device. 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 may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators may consider changing the default incoming connection port number to be any suitable value other than port 23.
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.