CVE-2020-20248 in MikroTik
Summary
by MITRE • 07/20/2021
Mikrotik RouterOs before stable 6.47 suffers from an uncontrolled resource consumption in the memtest process. An authenticated remote attacker can cause a Denial of Service due to overloading the systems CPU.
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Analysis
by VulDB Data Team • 07/22/2021
The vulnerability identified as CVE-2020-20248 affects MikroTik RouterOS versions prior to stable release 6.47, presenting a critical uncontrolled resource consumption flaw within the memtest process. This vulnerability specifically targets the system's memory testing functionality, which is designed to verify hardware memory integrity during system operations. The flaw allows an authenticated remote attacker to exploit the memtest process in a manner that can lead to excessive cpu utilization and ultimately system denial of service. The vulnerability resides in the improper handling of resource allocation during memory testing operations, creating a condition where malicious input can cause the system to consume resources at an unbounded rate.
The technical implementation of this vulnerability stems from inadequate resource management within the memtest component of RouterOS. When the memtest process is invoked, either through legitimate system operations or through crafted malicious input, the process fails to properly enforce resource limits or validate input parameters. This allows an authenticated attacker who can access the router's management interface to trigger memory testing sequences that consume excessive cpu cycles without proper bounds checking or resource exhaustion prevention mechanisms. The vulnerability operates at the system level where the memtest process is designed to perform memory diagnostics, but the implementation lacks proper resource consumption controls that would normally prevent such excessive utilization. This represents a classic case of insufficient resource management and can be categorized under CWE-770, which addresses allocation of resources without proper limits.
The operational impact of CVE-2020-20248 extends beyond simple service disruption to potentially compromise the availability of critical network infrastructure. When exploited, the vulnerability can cause sustained high cpu utilization that renders the router unresponsive to legitimate management requests and network traffic processing. Network administrators may find their routers becoming unmanageable, with the system eventually becoming so overloaded that it cannot process basic routing functions or maintain network connectivity for connected devices. The vulnerability is particularly concerning in enterprise and service provider environments where router availability is critical for maintaining network operations. Attackers can maintain the denial of service condition for extended periods, potentially causing cascading failures throughout network infrastructure that relies on the affected router for connectivity.
Mitigation strategies for this vulnerability require immediate implementation of the official MikroTik firmware update to version 6.47 or later, which contains the necessary patches to address the resource consumption flaw. Network administrators should also implement additional monitoring and alerting mechanisms to detect unusual cpu utilization patterns that may indicate exploitation attempts. Access controls should be strengthened to limit authentication to only authorized personnel, as the vulnerability requires authentication to exploit. Network segmentation and firewall rules can help limit the attack surface by restricting access to router management interfaces from untrusted networks. The vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a form of resource exhaustion attack that can be classified under the broader category of availability attacks in cybersecurity frameworks. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security updates and maintain visibility into router configurations and operational status.