CVE-2020-20264 in MikroTik
Summary
by MITRE • 05/19/2021
Mikrotik RouterOs before 6.47 (stable tree) in the /ram/pckg/advanced-tools/nova/bin/netwatch process. An authenticated remote attacker can cause a Denial of Service due to a divide by zero error.
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Analysis
by VulDB Data Team • 05/22/2021
The vulnerability identified as CVE-2020-20264 affects MikroTik RouterOS versions prior to 6.47 within the advanced-tools package, specifically in the netwatch binary process located at /ram/pckg/advanced-tools/nova/bin/netwatch. This issue represents a critical security flaw that allows authenticated remote attackers to execute a denial of service attack against affected systems. The vulnerability manifests through a divide by zero error condition that occurs during the processing of network monitoring operations within the router's advanced tools framework.
The technical implementation of this vulnerability resides in the netwatch utility which is part of MikroTik's advanced networking tools suite designed for network monitoring and diagnostics. When an authenticated attacker sends specifically crafted network monitoring requests to the affected router, the netwatch process encounters a mathematical division operation where the divisor becomes zero, causing the process to crash and resulting in a complete denial of service condition. This divide by zero error represents a classic software bug pattern that violates fundamental programming principles and can be classified under CWE-369 as "Divide by Zero" within the Common Weakness Enumeration framework.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the core network monitoring capabilities of MikroTik routers. Network administrators who rely on the advanced-tools package for network diagnostics, monitoring, and troubleshooting will experience complete service unavailability when the netwatch process crashes, potentially leading to extended network downtime and loss of critical monitoring data. The vulnerability is particularly concerning because it requires only authentication credentials to exploit, meaning that any attacker with valid user access can trigger the denial of service condition. This aligns with ATT&CK technique T1499.004 which covers "Network Denial of Service" and demonstrates how authenticated access can be leveraged to compromise system availability.
The affected environment specifically targets MikroTik routers running RouterOS versions before 6.47 in the stable tree, making this vulnerability particularly widespread across various network infrastructure deployments. Organizations utilizing MikroTik devices for critical network operations face significant risk as this vulnerability can be exploited by both malicious insiders and external attackers who have obtained valid authentication credentials. The fact that the vulnerability exists in a process located in the RAM-based package directory indicates that it affects runtime operations rather than configuration files, making it more difficult to mitigate through simple configuration changes. Security professionals should consider this vulnerability as part of broader network resilience planning, as it demonstrates how seemingly benign monitoring tools can become attack vectors when proper input validation and error handling mechanisms are absent. The vulnerability's impact on network availability makes it a critical concern for organizations that depend on continuous network monitoring and diagnostics capabilities provided by the affected software components.