CVE-2020-3235 in Management Pack for GoldenGate
Summary
by MITRE
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS Software and Cisco IOS XE Software on Catalyst 4500 Series Switches could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to insufficient input validation when the software processes specific SNMP object identifiers. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Note: To exploit this vulnerability by using SNMPv2c or earlier, the attacker must know the SNMP read-only community string for an affected system. To exploit this vulnerability by using SNMPv3, the attacker must know the user credentials for the affected system.
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Analysis
by VulDB Data Team • 11/24/2020
The vulnerability identified as CVE-2020-3235 represents a critical denial of service weakness within the Simple Network Management Protocol subsystem of Cisco IOS and IOS XE software running on Catalyst 4500 series switches. This flaw specifically manifests in the insufficient validation of input parameters when processing certain SNMP object identifiers, creating a pathway for authenticated remote attackers to disrupt network operations. The vulnerability affects devices that utilize SNMP versions 2c and earlier, as well as SNMPv3, making it particularly concerning given the widespread deployment of these protocols in enterprise network management environments. The attack vector requires an authenticated session, meaning that adversaries must first obtain valid credentials or community strings to exploit the weakness, though this authentication requirement does not mitigate the potential impact of successful exploitation.
The technical exploitation of CVE-2020-3235 occurs when a crafted SNMP packet containing malformed object identifiers is transmitted to an affected switch. This malformed input triggers a processing error within the SNMP subsystem that ultimately leads to a system reload or reboot. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize or verify the structure of SNMP object identifiers before processing them within the switch's operational environment. This type of input validation flaw aligns with CWE-20, which describes "Improper Input Validation" as a fundamental weakness in software design that allows malformed data to cause unexpected behavior. The impact of such a vulnerability extends beyond simple service disruption, as network switches serve as critical infrastructure components that, when rendered unavailable, can cascade into broader network outages and service interruptions.
From an operational perspective, the exploitation of CVE-2020-3235 creates a significant risk for network administrators and security operations teams responsible for maintaining availability of core network infrastructure. The DoS condition resulting from device reloads can disrupt network services for extended periods while system recovery occurs, potentially affecting business operations and requiring immediate incident response actions. The vulnerability's requirement for authentication means that it is less likely to be exploited by casual attackers, but it remains a serious concern for threat actors who have already gained access to network management credentials. This characteristic places the vulnerability in the ATT&CK framework under the T1078 technique category, which involves valid accounts and legitimate credentials, making it particularly dangerous in environments where credential security is not adequately maintained. The impact on network availability and the potential for cascading failures within larger network infrastructures makes this vulnerability particularly attractive to attackers seeking to cause maximum disruption.
Mitigation strategies for CVE-2020-3235 should focus on both immediate remediation and long-term security hardening measures. Cisco has released software updates and patches that address the input validation flaw in the SNMP subsystem, and network administrators should prioritize applying these updates to affected devices. Additionally, implementing network segmentation and access controls can limit the attack surface by restricting access to SNMP management interfaces to authorized personnel only. The principle of least privilege should be enforced by ensuring that SNMP community strings and user credentials have minimal necessary permissions and are regularly rotated. Network monitoring solutions should be configured to detect unusual SNMP traffic patterns that might indicate exploitation attempts, and security teams should implement proper credential management practices to prevent unauthorized access. Organizations should also consider disabling SNMPv1 and SNMPv2c if SNMPv3 is available and properly configured, as these older versions lack the security features of SNMPv3 and are more susceptible to various attacks including this particular vulnerability. The implementation of these defensive measures aligns with cybersecurity frameworks such as NIST SP 800-53 and ISO 27001, which emphasize the importance of input validation and access control in maintaining system integrity and availability.