CVE-2017-7285 in MikroTik
Summary
by MITRE
A vulnerability in the network stack of MikroTik Version 6.38.5 released 2017-03-09 could allow an unauthenticated remote attacker to exhaust all available CPU via a flood of TCP RST packets, preventing the affected router from accepting new TCP connections.
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Analysis
by VulDB Data Team • 07/16/2024
The vulnerability identified as CVE-2017-7285 represents a critical denial of service weakness within MikroTik routers running firmware version 6.38.5 and earlier. This flaw exists within the network stack implementation of the router operating system, specifically affecting how the device processes incoming TCP RST packets. The vulnerability was disclosed in March 2017 and affects a significant number of MikroTik devices that were widely deployed in enterprise and residential networking environments. The flaw stems from inadequate input validation and resource management within the TCP connection handling mechanism, creating a scenario where malicious actors can exploit the system's response to malformed or excessive TCP reset signals.
The technical nature of this vulnerability can be categorized under CWE-400, which deals with unspecified resource management errors, and more specifically aligns with CWE-122, indicating improper restriction of operations within a recognized security boundary. The flaw operates through a simple yet effective mechanism where an attacker sends a flood of TCP RST packets to the target MikroTik router. Each packet triggers a processing routine within the router's kernel that consumes CPU cycles without proper rate limiting or resource exhaustion protection. The vulnerability is particularly dangerous because it requires no authentication credentials to exploit, making it accessible to any remote attacker with network connectivity to the affected device. The router's TCP stack fails to properly handle the volume of reset packets, leading to a gradual depletion of available CPU resources until the system becomes unresponsive.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire network infrastructures. When successfully exploited, the attack causes the router to become unresponsive to legitimate network traffic, effectively creating a network outage for all connected devices. The affected router cannot accept new TCP connections, which means that services relying on TCP communication such as web browsing, email, file transfers, and remote management access become unavailable. This disruption can cascade through network environments, particularly in scenarios where the MikroTik device serves as a gateway or firewall for multiple network segments. The attack is particularly insidious because it can be executed from anywhere on the internet, and the volume of traffic required to cause the denial of service is relatively low compared to other DoS attacks. Network administrators may experience difficulty in detecting the attack initially since it appears as normal network traffic, but the system gradually becomes unresponsive over time.
Mitigation strategies for CVE-2017-7285 primarily involve applying the official firmware updates released by MikroTik to address the vulnerability. The vendor issued patches that implement proper rate limiting and resource management for TCP RST packet processing, preventing the CPU exhaustion that enabled the attack. Network administrators should also consider implementing network-level protections such as firewall rules that limit the rate of incoming TCP RST packets from external sources, though this approach may inadvertently block legitimate traffic. Additionally, organizations should implement monitoring solutions that can detect unusual CPU utilization patterns or sudden increases in TCP RST packet processing that might indicate an active attack. The vulnerability demonstrates the importance of maintaining up-to-date firmware and implementing network segmentation to limit the potential impact of such attacks. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1499.004 for network denial of service and T1071.004 for application layer protocol usage, highlighting the need for robust network infrastructure security measures and continuous vulnerability assessment procedures.