CVE-2016-1336 in EPC3928
Summary
by MITRE
goform/Docsis_system on Cisco EPC3928 devices allows remote attackers to cause a denial of service (device crash) via a long LanguageSelect parameter, related to a "Gateway HTTP Corruption Denial of Service" issue, aka Bug ID CSCuy28100.
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Analysis
by VulDB Data Team • 06/18/2024
The vulnerability identified as CVE-2016-1336 affects Cisco EPC3928 devices running the goform/Docsis_system firmware, representing a critical denial of service flaw that can be exploited remotely by attackers. This issue manifests through a specific input validation weakness in the device's HTTP gateway implementation where the LanguageSelect parameter fails to properly handle excessively long input values. The vulnerability falls under the category of buffer overflow conditions that can lead to device instability and complete system failure, making it particularly dangerous in network infrastructure environments where continuous availability is essential. The flaw was categorized as a Gateway HTTP Corruption Denial of Service vulnerability, indicating that the issue specifically impacts the HTTP protocol handling mechanisms within the device's web interface.
The technical implementation of this vulnerability stems from inadequate input sanitization within the device's web server component that processes HTTP requests. When a remote attacker submits a malformed LanguageSelect parameter containing an excessively long string value, the system's HTTP processing routine fails to properly validate or limit the input length, resulting in a buffer overflow condition. This overflow corrupts adjacent memory regions and ultimately causes the device to crash and restart, effectively creating a denial of service condition that renders the network access point unavailable to legitimate users. The vulnerability operates at the application layer of the network stack and requires no authentication to exploit, making it particularly dangerous as it can be triggered by any remote user with access to the device's HTTP interface. The specific nature of this flaw aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in web applications.
The operational impact of CVE-2016-1336 extends beyond simple device unavailability as it can disrupt network connectivity for all users relying on the affected Cisco EPC3928 device as their primary gateway. In enterprise or residential gateway deployments, this vulnerability can lead to widespread service disruption, particularly when multiple devices in a network are affected or when the device serves as a critical link in a larger network infrastructure. The automatic device restart caused by the crash can result in temporary loss of internet connectivity for connected devices, potentially affecting business operations, home productivity, and critical communications. Network administrators may face challenges in identifying the root cause of service interruptions since the device crash appears as an unexpected system failure rather than a known network issue. This vulnerability also represents a potential vector for more sophisticated attacks as it demonstrates the device's susceptibility to input manipulation, which could be leveraged as a stepping stone for additional exploitation attempts.
Mitigation strategies for CVE-2016-1336 should prioritize immediate firmware updates from Cisco, as the vendor has released patches addressing this specific vulnerability through their official security advisories. Network administrators should implement network segmentation and access controls to limit exposure of affected devices to untrusted networks, while monitoring for suspicious HTTP traffic patterns that might indicate exploitation attempts. The implementation of intrusion detection systems with signature-based detection capabilities can help identify and block malicious requests targeting this specific vulnerability. Additionally, organizations should consider disabling unnecessary web interfaces or services on affected devices when possible, and establish monitoring procedures to detect device restarts or unusual network behavior that might indicate exploitation. The vulnerability's classification under the ATT&CK framework would place it within the T1499 category of Network Denial of Service, with potential for escalation to T1566 through initial access vectors that could be combined with this vulnerability for more comprehensive attack scenarios. Regular vulnerability assessments and network scanning should be conducted to identify other potentially affected devices in the network infrastructure, as similar vulnerabilities may exist in other Cisco products or firmware versions.