CVE-2020-20247 in MikroTik
Summary
by MITRE • 05/04/2021
Mikrotik RouterOs before 6.46.5 (stable tree) suffers from a memory corruption vulnerability in the /nova/bin/traceroute process. An authenticated remote attacker can cause a Denial of Service due via the loop counter variable.
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Analysis
by VulDB Data Team • 05/07/2021
The vulnerability identified as CVE-2020-20247 affects MikroTik RouterOS versions prior to 6.46.5, specifically within the /nova/bin/traceroute process. This memory corruption flaw represents a significant security concern for network infrastructure devices that rely on MikroTik routers for their operations. The issue manifests when an authenticated remote attacker exploits a loop counter variable within the traceroute functionality, leading to system instability and potential service disruption. The vulnerability resides in the stable tree version of RouterOS, indicating it affects widely deployed production systems that have not yet received the necessary security patches.
The technical implementation of this vulnerability stems from improper handling of loop counter variables within the traceroute binary process. When an attacker sends specially crafted network traffic or executes specific commands through the authenticated interface, the loop counter variable becomes corrupted or overflows, causing memory allocation issues that ultimately result in system crashes or complete denial of service. This type of memory corruption vulnerability falls under the CWE-121 category of stack-based buffer overflow, though the specific manifestation in this case involves loop counter manipulation rather than traditional buffer overflow conditions. The flaw demonstrates how seemingly benign network diagnostic tools can become attack vectors when proper input validation and boundary checking mechanisms are absent.
The operational impact of CVE-2020-20247 extends beyond simple service disruption to potentially compromise entire network infrastructures that depend on affected MikroTik devices. Organizations utilizing vulnerable RouterOS versions face the risk of unauthorized attackers causing deliberate denial of service attacks that could disrupt critical network services, affect business continuity, and potentially create opportunities for further exploitation. The authenticated nature of the attack means that adversaries must first gain access credentials, but this does not significantly reduce the threat level since network administrators often maintain relatively open access for operational purposes. The vulnerability affects the fundamental network diagnostic capabilities of these devices, making it particularly dangerous in environments where network monitoring and troubleshooting are critical for maintaining service availability.
Mitigation strategies for this vulnerability center around immediate deployment of MikroTik RouterOS version 6.46.5 or later, which contains the necessary patches to address the memory corruption issue in the traceroute process. Network administrators should also implement additional monitoring and access controls to limit the potential impact of authenticated attacks, including restricting administrative access to trusted personnel and implementing multi-factor authentication mechanisms. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service, highlighting the importance of maintaining up-to-date firmware and implementing proper network segmentation to limit the scope of potential attacks. Organizations should also conduct comprehensive vulnerability assessments to identify all instances of affected RouterOS versions within their network infrastructure and establish regular patch management procedures to prevent similar issues from arising in the future.