CVE-2020-20267 in MikroTik
Summary
by MITRE • 05/11/2021
Mikrotik RouterOs before 6.47 (stable tree) suffers from a memory corruption vulnerability in the /nova/bin/resolver process. An authenticated remote attacker can cause a Denial of Service due to invalid memory access.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/15/2021
The vulnerability identified as CVE-2020-20267 affects Mikrotik RouterOS versions prior to 6.47, specifically within the /nova/bin/resolver process. This memory corruption flaw represents a critical security weakness that can be exploited by authenticated remote attackers to disrupt system operations. The vulnerability resides in the network resolution component of the router operating system, which handles DNS queries and related network resolution functions. The affected process operates with elevated privileges and manages critical network infrastructure functions, making it a prime target for attackers seeking to compromise network availability.
The technical implementation of this vulnerability stems from improper memory handling within the resolver process, where invalid memory access patterns can occur when processing certain network requests. This type of memory corruption vulnerability typically manifests when the system attempts to access memory locations that have not been properly allocated or have already been freed. The flaw allows an authenticated attacker to craft specific network packets or DNS queries that trigger the memory corruption, leading to unpredictable system behavior. According to CWE classification, this vulnerability maps to CWE-125: Out-of-bounds Read, as the system attempts to access memory beyond its allocated boundaries. The issue demonstrates characteristics of a remote code execution vector, though the immediate impact is limited to denial of service conditions.
The operational impact of CVE-2020-20267 extends beyond simple service disruption, as it can affect critical network infrastructure components that rely on the resolver process for proper functionality. Network administrators may experience complete loss of DNS resolution capabilities, which can cascade into broader network outages affecting multiple services and applications that depend on name resolution. The vulnerability's authenticated nature means that attackers must first establish valid credentials to exploit the flaw, but this requirement does not significantly mitigate the risk given that many network devices are configured with default credentials or have weak authentication mechanisms. Organizations using affected Mikrotik devices face potential operational disruptions that could last until the vulnerability is patched and the system is rebooted to clear corrupted memory states.
Mitigation strategies for this vulnerability should prioritize immediate patching of all affected RouterOS installations to version 6.47 or later. Network administrators should also implement network segmentation and access controls to limit the attack surface, ensuring that only authorized personnel can access router management interfaces. Monitoring systems should be configured to detect unusual network traffic patterns or DNS resolution anomalies that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1072: Software Deployment Tools, as attackers may leverage compromised router credentials to deploy malicious payloads or establish persistent access. Additionally, organizations should consider implementing network intrusion detection systems that can identify malformed DNS queries or unusual memory access patterns. Regular security audits of network infrastructure should include verification of router firmware versions and authentication configurations to prevent exploitation of similar vulnerabilities in the future.