CVE-2018-0160 in IOS XE
Summary
by MITRE
A vulnerability in Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper management of memory resources, referred to as a double free. An attacker could exploit this vulnerability by sending crafted SNMP packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. To exploit this vulnerability via SNMP Version 2c or earlier, the attacker must know the SNMP read-only community string for an affected system. To exploit this vulnerability via SNMP Version 3, the attacker must know the user credentials for the affected system. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS XE Software, have been configured to be queried over SNMP, and have Network Address Translation (NAT) enabled. Cisco Bug IDs: CSCve75818.
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Analysis
by VulDB Data Team • 02/06/2021
The vulnerability described in CVE-2018-0160 represents a critical memory management flaw within the Simple Network Management Protocol subsystem of Cisco IOS XE Software, specifically manifesting as a double free condition that can be exploited to induce denial of service attacks. This weakness falls under the Common Weakness Enumeration category CWE-415, which addresses double free vulnerabilities where the same memory block is freed twice, potentially leading to memory corruption and system instability. The vulnerability exists in the SNMP processing logic of affected Cisco devices, creating a scenario where an authenticated remote attacker can manipulate the memory management routines through carefully crafted SNMP packets.
The technical exploitation of this vulnerability requires an attacker to possess valid credentials for the targeted system, with different credential requirements based on SNMP version used. For SNMP Version 2c and earlier versions, attackers must know the SNMP read-only community string, while SNMP Version 3 exploitation requires valid user credentials including username and authentication parameters. The attack vector specifically leverages the interaction between SNMP packet processing and Network Address Translation functionality, making devices with NAT enabled particularly vulnerable. This combination of factors creates a precise exploitation scenario where the double free error occurs during memory deallocation when processing malformed SNMP messages, leading to unpredictable system behavior and eventual device reload.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network availability and reliability. When successfully exploited, the vulnerability forces the affected Cisco device to undergo an automatic reload process, effectively creating a denial of service condition that can persist until manual intervention occurs. Network administrators face significant challenges in mitigating this vulnerability since it requires both authentication credentials and specific configuration conditions to be exploited, making it difficult to detect and prevent through conventional network monitoring. The vulnerability affects a broad range of Cisco devices running vulnerable releases of IOS XE Software, including routers and switches that have been configured for SNMP monitoring and NAT functionality.
Organizations must implement comprehensive mitigation strategies that address both the immediate vulnerability and underlying security posture issues. The primary recommendation involves applying the relevant Cisco security patches and updates that correct the memory management routines within the SNMP subsystem. Additionally, network segmentation and access control measures should be strengthened to limit SNMP access to authorized personnel only, while disabling unnecessary SNMP versions and implementing robust credential management practices. The vulnerability also highlights the importance of network monitoring for unusual reload patterns and SNMP traffic anomalies, as these can serve as early indicators of exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and denial of service through protocol manipulation, emphasizing the need for layered security controls that address both network infrastructure integrity and access control measures.