CVE-2020-22844 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 SMB requests.
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Analysis
by VulDB Data Team • 03/04/2022
The vulnerability identified as CVE-2020-22844 represents a critical buffer overflow flaw within Mikrotik RouterOS version 6.47 that specifically affects the Server Message Block implementation. This issue resides in the network protocol handling layer of the router operating system, where improperly validated input from SMB requests can lead to memory corruption. The flaw is particularly concerning because it operates without requiring authentication, making it accessible to any remote attacker who can reach the affected device. The vulnerability manifests when the system processes malformed SMB packets that exceed the allocated buffer space, causing the application to overwrite adjacent memory locations and potentially leading to system instability.
From a technical perspective, this buffer overflow occurs within the SMB server component of RouterOS, which handles file sharing and network communication protocols. The flaw is classified under CWE-121 as a stack-based buffer overflow, where the attacker can manipulate the SMB request structure to exceed the predetermined buffer limits. The attack vector involves sending specially crafted SMB packets that trigger the overflow condition, causing the system to crash or become unresponsive. The vulnerability affects the core network services of the router, making it particularly dangerous for network infrastructure devices that rely on SMB functionality for file sharing or administrative access.
The operational impact of CVE-2020-22844 extends beyond simple denial of service, as it can severely disrupt network operations and compromise the availability of critical services. Organizations relying on Mikrotik routers for their network infrastructure face potential downtime when this vulnerability is exploited, especially in environments where SMB services are enabled for file sharing or printer access. The unauthenticated nature of the attack means that adversaries can exploit this vulnerability without requiring valid credentials, making it particularly dangerous for devices exposed to public networks or untrusted environments. Network administrators may experience unexpected router reboots or complete service outages that can affect business continuity and network availability.
Mitigation strategies for CVE-2020-22844 should focus on immediate patching of affected RouterOS versions, with Mikrotik releasing updates that address the buffer overflow condition in their SMB implementation. Organizations should disable SMB services on affected routers when patches are not immediately available, as this eliminates the attack surface for exploitation. Network segmentation and firewall rules can help limit exposure by blocking SMB traffic to affected devices, while monitoring systems should be configured to detect unusual SMB traffic patterns that may indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries leverage protocol flaws to disrupt network services. Additionally, implementing intrusion detection systems that can identify malformed SMB packets and conducting regular vulnerability assessments of network infrastructure will help prevent exploitation of this and similar vulnerabilities in the future.