CVE-2014-3814 in ScreenOS
Summary
by MITRE
The Juniper Networks NetScreen Firewall devices with ScreenOS before 6.3r17, when configured to use the internal DNS lookup client, allows remote attackers to cause a denial of service (crash and reboot) via a sequence of malformed packets to the device IP.
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Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2014-3814 affects Juniper Networks NetScreen Firewall devices running ScreenOS versions prior to 6.3r17. This issue specifically manifests when the firewall is configured to utilize its internal DNS lookup client functionality, creating a critical weakness that can be exploited by remote attackers to execute a denial of service attack. The vulnerability represents a significant security concern for organizations relying on these network security devices, as it can lead to complete service disruption and system reboot cycles that compromise network availability and operational continuity.
The technical flaw resides in the improper handling of malformed DNS packets within the internal DNS lookup client implementation of the ScreenOS operating system. When the firewall receives a sequence of specially crafted malformed packets addressed to the device IP, the system fails to properly validate or process these inputs, leading to a system crash and subsequent automatic reboot. This vulnerability is classified under CWE-129, which deals with insufficient validation of inputs that can result in buffer overflows or other memory corruption issues. The flaw demonstrates characteristics of a buffer overflow vulnerability where the device's DNS client module does not adequately sanitize incoming packet data, allowing malicious input to trigger unexpected system behavior.
The operational impact of this vulnerability extends beyond simple service disruption, as it can potentially be exploited to create persistent denial of service conditions that may require manual intervention to restore system functionality. Network administrators face the challenge of maintaining continuous availability while managing the risk of system-wide outages that can occur without warning. The vulnerability affects organizations that depend on NetScreen firewalls for network security, potentially compromising their ability to maintain secure network boundaries and protect against other threats during the periods when the device is offline due to the DoS attack. This type of attack aligns with ATT&CK technique T1499.004, which involves network disruption attacks targeting network infrastructure components.
Mitigation strategies for CVE-2014-3814 should prioritize immediate patching of affected devices to ScreenOS version 6.3r17 or later, which contains the necessary fixes to properly validate DNS packet inputs. Organizations should also implement network segmentation and access controls to limit exposure of affected devices to untrusted networks, while monitoring network traffic for suspicious DNS packet patterns that may indicate exploitation attempts. Additionally, network administrators should consider disabling the internal DNS lookup client functionality if it is not essential for network operations, and implementing intrusion detection systems that can identify and alert on malformed DNS traffic patterns. The vulnerability underscores the importance of maintaining current firmware versions and conducting regular security assessments of network infrastructure components to prevent exploitation of known weaknesses that could compromise network security and availability.