Cisco NX-OS-based devices contain a buffer overflow vulnerability in the Simple Network Management Protocol (SNMP) subsystem. An authenticated, remote attacker who can submit a malicious SNMP query via UDP port 161 could exploit the vulnerability to trigger a buffer overflow condition in the SNMP component of the device. Successful exploitation could allow the attacker to execute arbitrary code with elevated privileges.
SNMP is disabled by default and must be explicitly configured by an administrator. Because SNMP is primarily a UDP-based protocol, no TCP three-way handshake is required to exploit this vulnerability, and the malicious request could contain a spoofed origin. The attacker must know the configured community strings for SNMP version 1 and version 2. Exploitation also requires a valid username and password when a device is configured for SNMP version 3.
Cisco has confirmed the vulnerability in a security advisory and has released updated software.
Indicators of Compromise
Cisco NX-OS devices running an affected release of Cisco NX-OS Software are vulnerable.
Cisco has published a list of affected Cisco NX-OS Software Releases and affected Cisco NX-OS devices in a security advisory. The Vendor Announcements section of this alert contains a link to the advisory.
The vulnerability is due to insufficient validation of user-supplied input processed by the SNMP subsystem implemented in the affected software. The vulnerability can be triggered via SNMP over IPv4 and IPv6.
An authenticated, remote attacker could exploit this vulnerability by submitting a malicious SNMP query via UDP port 161 to the targeted device. If successful, the query could trigger a buffer overflow condition in the SNMP component of the affected device. An attacker could use the buffer overflow condition to execute arbitrary code with elevated privileges.
To exploit this vulnerability, an attacker must be able to authenticate to a targeted device. In addition, SNMP must be enabled and explicitly configured by an administrator. SNMP is disabled by default. These requirements reduce the likelihood of a successful 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.
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.