CVE-2017-17901 in P-660HW
Summary
by MITRE
ZyXEL P-660HW v3 devices allow remote attackers to cause a denial of service (CPU consumption) via a flood of IP packets with a TTL of 1.
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Analysis
by VulDB Data Team • 01/19/2023
The vulnerability identified as CVE-2017-17901 affects ZyXEL P-660HW v3 broadband routers, representing a significant denial of service weakness that can be exploited remotely by malicious actors. This issue manifests through a specific packet flooding attack pattern where attackers send a high volume of IP packets with a time-to-live value set to 1, causing the device's central processing unit to consume excessive resources. The flaw demonstrates a critical design oversight in the router's packet processing mechanisms, where the device fails to properly handle or rate-limit incoming packets with this specific TTL value, leading to complete service disruption for legitimate users.
The technical root cause of this vulnerability stems from insufficient input validation and packet filtering capabilities within the router's network stack implementation. When the device receives IP packets with TTL=1, the processing logic does not adequately distinguish between legitimate network traffic and malicious flood attempts. This weakness creates a resource exhaustion scenario where the CPU continuously processes these packets without proper rate limiting or traffic shaping mechanisms, ultimately consuming all available processing power and rendering the device incapable of forwarding legitimate network traffic. The vulnerability aligns with CWE-400, which classifies improper resource management issues in network devices, and specifically relates to the lack of proper packet filtering and rate limiting controls.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render the entire network infrastructure unusable for extended periods. Network administrators face the challenge of maintaining service availability when attackers can easily exploit this weakness using readily available tools to generate packet floods. The remote nature of the attack means that adversaries do not require physical access or network credentials to execute the denial of service attack, making it particularly dangerous for enterprise and residential networks. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the T1498 category, which covers network denial of service attacks, and can be classified as a resource exhaustion attack pattern.
Mitigation strategies for CVE-2017-17901 should focus on both immediate protective measures and long-term architectural improvements. Network administrators should implement ingress filtering and rate limiting mechanisms at the network perimeter to prevent packets with TTL=1 from reaching the vulnerable router. The device firmware should be updated to the latest available version from ZyXEL, as the company has released patches addressing this specific vulnerability. Additional protective measures include implementing network access control lists to block suspicious traffic patterns, deploying intrusion detection systems that can identify and alert on packet flooding attempts, and establishing monitoring protocols to detect unusual CPU utilization patterns that may indicate exploitation attempts. Organizations should also consider network segmentation to isolate critical infrastructure from potentially compromised devices and maintain detailed network traffic logs to aid in forensic analysis and incident response activities.