CVE-2018-0170 in IOS XE
Summary
by MITRE
A vulnerability in the Cisco Umbrella Integration feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition, related to the OpenDNS software. The vulnerability is due to a logic error that exists when handling a malformed incoming packet, leading to access to an internal data structure after it has been freed. An attacker could exploit this vulnerability by sending crafted, malformed IP packets to an affected device. A successful exploit could allow the attacker to cause an affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvb86327.
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Analysis
by VulDB Data Team • 02/06/2021
The vulnerability identified as CVE-2018-0170 resides within Cisco IOS XE Software's Cisco Umbrella Integration feature, specifically affecting devices that utilize OpenDNS software components. This security flaw represents a critical denial of service vulnerability that can be exploited remotely without authentication, posing significant operational risks to network infrastructure. The vulnerability stems from improper memory management practices within the packet processing logic, creating a scenario where an attacker can manipulate device behavior through carefully crafted network traffic.
The technical root cause of this vulnerability involves a logic error in how the software handles malformed incoming IP packets, specifically related to memory allocation and deallocation processes. When an affected device receives malformed packets, the system attempts to access memory locations that have already been freed, creating a condition known as use-after-free vulnerability. This memory management error falls under the CWE-416 category of "Use After Free" vulnerabilities, where software continues to reference memory after it has been released back to the system. The improper handling of these packets leads to unpredictable behavior and system instability.
The operational impact of this vulnerability extends beyond simple service disruption, as successful exploitation can result in complete device reloads and extended network downtime. Attackers can trigger this condition by sending specifically crafted malformed IP packets to targeted devices, requiring minimal technical expertise to execute. The DoS condition affects the availability of critical network services, potentially disrupting business operations and requiring manual intervention for device recovery. This vulnerability particularly impacts organizations relying on Cisco Umbrella Integration for security policy enforcement and DNS filtering services.
Mitigation strategies for CVE-2018-0170 should prioritize immediate software updates from Cisco, specifically addressing the identified CSCvb86327 bug. Organizations should implement network segmentation to limit exposure, deploy intrusion prevention systems that can detect and block malformed packet patterns, and establish monitoring protocols to identify potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1498, which covers "Network Denial of Service" attacks, and represents a common vector for disrupting network availability. Security teams should also consider implementing rate limiting on incoming packets and establishing automated alerting mechanisms to detect unusual traffic patterns that might indicate exploitation attempts.