CVE-2017-6641 in Remote Expert Manager
Summary
by MITRE
A vulnerability in the TCP connection handling functionality of Cisco Remote Expert Manager Software 11.0.0 could allow an unauthenticated, remote attacker to disable TCP ports and cause a denial of service (DoS) condition on an affected system. The vulnerability is due to a lack of rate-limiting functionality in the TCP Listen application of the affected software. An attacker could exploit this vulnerability by sending a crafted TCP traffic stream in which specific types of TCP packets are flooded to an affected device, for example a TCP packet stream in which the TCP FIN bit is set in all the TCP packets. A successful exploit could allow the attacker to cause certain TCP listening ports on the affected system to stop accepting incoming connections for a period of time or until the affected device is restarted, resulting in a DoS condition. In addition, system resources, such as CPU and memory, could be exhausted during the attack. Cisco Bug IDs: CSCva29806.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 05/22/2017
The vulnerability described in CVE-2017-6641 represents a critical weakness in Cisco Remote Expert Manager Software version 11.0.0 that exposes systems to remote denial of service attacks through improper TCP connection handling mechanisms. This flaw resides within the TCP Listen application component of the software stack, where the absence of adequate rate-limiting controls creates an exploitable condition that can be leveraged by unauthenticated remote adversaries. The vulnerability specifically targets the software's inability to properly manage incoming TCP traffic patterns, making it susceptible to crafted packet flooding attacks that can overwhelm the system's TCP port handling capabilities.
The technical implementation of this vulnerability stems from insufficient input validation and traffic rate limiting within the TCP connection processing pipeline. Attackers can exploit this weakness by crafting specific TCP packet streams that contain the TCP FIN bit set in every packet, creating a sustained flood of connection termination requests that the system cannot properly handle. This particular packet structure triggers a cascading failure in the TCP listening port management, causing affected ports to cease accepting new incoming connections temporarily or until system restart. The flaw operates at the network protocol level, specifically targeting the TCP state machine implementation and connection handling logic that governs how the system processes incoming connection requests.
From an operational perspective, this vulnerability presents a significant risk to network availability and system stability, as successful exploitation can result in complete service disruption for critical TCP listening applications. The DoS condition can persist for extended periods until manual intervention occurs, potentially requiring system restarts to restore normal operations. Additionally, the attack methodology can lead to resource exhaustion across multiple system components, with CPU utilization and memory consumption reaching critical levels during active exploitation attempts. This resource depletion further compounds the impact by potentially affecting other system functions and creating cascading failures that extend beyond the immediate TCP port disruption.
The vulnerability aligns with CWE-770, which addresses the allocation of resources without proper limits or controls, and represents a classic example of inadequate traffic rate limiting in network applications. From an adversarial perspective, this weakness maps to ATT&CK technique T1499.004, which involves network disruption through resource exhaustion attacks. The attack vector requires only network access to the affected system, making it particularly dangerous as it can be executed from remote locations without requiring authentication credentials. Organizations utilizing Cisco Remote Expert Manager Software 11.0.0 should consider immediate mitigation strategies including network segmentation, firewall rule implementation to restrict TCP traffic, and application-level rate limiting controls to prevent packet flooding attacks. Regular monitoring of system resource utilization and network traffic patterns can help detect potential exploitation attempts before they cause significant service disruption. Cisco has addressed this vulnerability through software updates and patches, emphasizing the importance of maintaining current system versions to protect against known exploits that target protocol implementation weaknesses in network management applications.