CVE-2019-3943 in MikroTik
Summary
by MITRE
MikroTik RouterOS versions Stable 6.43.12 and below, Long-term 6.42.12 and below, and Testing 6.44beta75 and below are vulnerable to an authenticated, remote directory traversal via the HTTP or Winbox interfaces. An authenticated, remote attack can use this vulnerability to read and write files outside of the sandbox directory (/rw/disk).
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/28/2023
The vulnerability identified as CVE-2019-3943 affects MikroTik RouterOS firmware versions across multiple release channels including Stable 6.43.12 and below, Long-term 6.42.12 and below, and Testing 6.44beta75 and below. This represents a critical directory traversal flaw that exists within the HTTP and Winbox administrative interfaces of MikroTik network devices. The vulnerability stems from insufficient input validation and improper path handling within the router operating system's file access mechanisms, allowing malicious actors with valid credentials to exploit this weakness remotely. The flaw specifically enables attackers to bypass the sandboxed directory structure that normally confines file operations to the /rw/disk directory, thereby granting unauthorized access to the underlying file system. This vulnerability is particularly concerning because it requires only authentication credentials to exploit, making it accessible to anyone with legitimate administrative access or those who have obtained valid login credentials through social engineering or other means.
The technical implementation of this directory traversal vulnerability involves the manipulation of file path parameters within the HTTP and Winbox protocols used by MikroTik devices for remote administration. When legitimate administrative users interact with the router through these interfaces, the system fails to properly sanitize or validate file path inputs, allowing attackers to append directory traversal sequences such as ../ or ..\ to access files outside the intended sandboxed environment. This flaw maps directly to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability's exploitation allows for both read and write operations beyond the designated file system boundaries, potentially enabling attackers to access sensitive configuration files, system binaries, or even modify critical system components. The impact extends beyond simple file access as it can lead to complete system compromise when combined with other attack vectors or when attackers can escalate privileges through the compromised file system access.
The operational impact of CVE-2019-3943 is severe and multifaceted, as it provides attackers with unauthorized access to critical system resources that could lead to complete network infrastructure compromise. Once exploited, attackers can read sensitive files containing system configurations, user credentials, or other confidential data stored on the router's file system. The write capability enables potential modification of system files, which could result in persistent backdoors, denial of service conditions, or complete system takeover. The vulnerability's presence in multiple firmware versions across different release channels indicates a widespread exposure across MikroTik deployments, affecting organizations that may have deployed these vulnerable versions across their network infrastructure. Network administrators face significant challenges in identifying exposed devices, as the vulnerability allows for remote exploitation without requiring physical access or complex attack chains. This makes the vulnerability particularly attractive to attackers who can leverage it for reconnaissance, lateral movement, or as a foothold for more sophisticated attacks within the network environment. The vulnerability's exploitation aligns with ATT&CK technique T1059.007 for command and control communication, and T1078 for valid accounts, as it requires legitimate administrative credentials to function effectively.
Mitigation strategies for CVE-2019-3943 should prioritize immediate firmware updates to versions that address the directory traversal vulnerability, as provided by MikroTik in their security advisories. Organizations must conduct comprehensive inventory audits to identify all affected MikroTik devices across their network infrastructure, particularly focusing on those with exposed HTTP or Winbox interfaces. Network segmentation and access control measures should be implemented to restrict access to these administrative interfaces, limiting exposure to trusted network segments only. The principle of least privilege should be enforced by ensuring that only authorized personnel have administrative access to these devices, with strong authentication mechanisms including multi-factor authentication where possible. Regular security assessments and vulnerability scanning should be conducted to identify any remaining vulnerable devices or potential misconfigurations that could allow exploitation of this vulnerability. System monitoring should be enhanced to detect unusual file access patterns or attempts to access restricted system directories, as these activities could indicate exploitation attempts. Additionally, organizations should implement network access controls that restrict external access to Winbox and HTTP administrative interfaces, ensuring that these services are only accessible from internal network segments or through secure VPN connections. The vulnerability's classification under CWE-22 and its potential exploitation through ATT&CK techniques emphasizes the importance of comprehensive security controls that address both the immediate technical flaw and broader security posture considerations.