CVE-2018-10070 in MikroTik
Summary
by MITRE
A vulnerability in MikroTik Version 6.41.4 could allow an unauthenticated remote attacker to exhaust all available CPU and all available RAM by sending a crafted FTP request on port 21 that begins with many '\0' characters, preventing the affected router from accepting new FTP connections. The router will reboot after 10 minutes, logging a "router was rebooted without proper shutdown" message.
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Analysis
by VulDB Data Team • 11/28/2024
This vulnerability exists within MikroTik routers running firmware version 6.41.4 and represents a significant denial of service weakness that can be exploited remotely without authentication. The flaw specifically affects the FTP service implementation on port 21, where an attacker can craft malicious requests containing numerous null characters at the beginning of the connection sequence. The vulnerability stems from inadequate input validation and resource handling within the FTP server component, which fails to properly process or reject malformed requests containing excessive null byte sequences. This design flaw allows the attacker to consume all available system resources through a single malicious connection attempt, effectively rendering the router inoperable.
The technical exploitation mechanism involves sending a specially crafted FTP request that begins with many null characters, which causes the router's FTP daemon to enter an infinite loop or consume excessive memory resources during processing. The vulnerability demonstrates characteristics consistent with a resource exhaustion attack pattern, where the attacker leverages the router's lack of proper input sanitization to trigger a condition where available CPU cycles and RAM are consumed entirely. The system's response to this attack is predictable and automated, with the router eventually rebooting after exactly 10 minutes of resource exhaustion, logging a specific message indicating an improper shutdown event. This behavior indicates that the router's operating system has built-in protective mechanisms that eventually force a reboot when system resources reach critical levels.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by attackers to perform persistent denial of service attacks against MikroTik routers in network environments. Network administrators may experience complete loss of FTP service availability, which could affect legitimate users attempting to access router management interfaces or file transfer services. The automatic reboot mechanism, while providing eventual recovery, creates a window of service unavailability that can be exploited for extended periods, potentially disrupting network operations and causing inconvenience to users. The vulnerability affects routers that have FTP service enabled, which is a common configuration in many network environments where file transfer capabilities are required for firmware updates or configuration management.
Security professionals should recognize this vulnerability as a variant of resource exhaustion attacks that align with common attack patterns documented in the attack tactics and techniques framework, particularly those related to service disruption and system availability compromise. The flaw also corresponds to specific weakness categories within the CWE database, specifically relating to improper input validation and resource management issues. Organizations should implement immediate mitigations including disabling unnecessary FTP services, applying firmware updates that address the vulnerability, and implementing network segmentation to limit exposure. Network monitoring should be enhanced to detect unusual patterns of connection attempts that may indicate exploitation attempts, and access controls should be enforced to restrict FTP service access to authorized users only. The vulnerability highlights the importance of proper input validation and resource management in embedded systems, particularly those handling network protocols where malformed requests can lead to system instability and denial of service conditions.