CVE-2020-22845 in MikroTik
Summary
by MITRE • 02/28/2022
A buffer overflow in Mikrotik RouterOS 6.47 allows unauthenticated attackers to cause a denial of service (DOS) via crafted FTP requests.
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Analysis
by VulDB Data Team • 03/04/2022
The vulnerability identified as CVE-2020-22845 represents a critical buffer overflow flaw within Mikrotik RouterOS version 6.47 that exposes networks to unauthenticated denial of service attacks. This issue specifically manifests when the router processes crafted FTP requests, allowing remote attackers to exploit the vulnerability without requiring any authentication credentials. The buffer overflow occurs within the FTP service implementation, where insufficient input validation permits maliciously constructed data packets to exceed the allocated buffer space, potentially leading to application crashes or system instability. Such vulnerabilities are particularly dangerous in network infrastructure devices as they can disrupt critical communications and services for extended periods.
The technical nature of this flaw aligns with CWE-121, which categorizes buffer overflow conditions where insufficient boundary checking allows data to overwrite adjacent memory locations. The vulnerability exploits the lack of proper input sanitization within the FTP protocol handler, specifically in how the router processes command arguments and response data. When an attacker sends malformed FTP requests containing oversized or specially crafted data sequences, the system fails to properly validate the input length before copying it into fixed-size buffers. This condition creates a predictable memory corruption scenario that can be reliably exploited to trigger system crashes, forcing the router to restart or become unresponsive. The attack vector is particularly concerning as it requires no authentication, making it accessible to any network entity capable of reaching the router's FTP service.
The operational impact of CVE-2020-22845 extends beyond simple service disruption to potentially compromise entire network infrastructures that rely on Mikrotik routers for critical connectivity. Organizations using affected RouterOS versions face significant risk of extended downtime, especially in environments where routers serve as primary network gateways or provide essential services like internet access, firewall protection, or network segmentation. The vulnerability can be exploited through various attack scenarios including automated scanning tools that systematically probe network devices for vulnerable services. Network administrators may experience cascading failures if multiple routers in the same network segment are affected, leading to widespread service outages. The attack can be executed from any location with network access to the vulnerable router, making it particularly difficult to defend against and trace.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates to versions that address the buffer overflow condition, as provided by Mikrotik through their official security advisories. Network administrators should disable unnecessary FTP services on affected routers until patches are applied, implementing firewall rules to block FTP traffic from untrusted networks. The implementation of intrusion detection systems can help identify exploitation attempts by monitoring for suspicious FTP request patterns that match known attack signatures. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all instances of affected RouterOS versions within their network infrastructure. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service, emphasizing the need for layered defensive measures including network segmentation, access control restrictions, and continuous monitoring of network traffic for anomalous patterns. Regular security audits and patch management procedures should be strengthened to prevent similar vulnerabilities from remaining unaddressed in the future.