CVE-2016-1268 in ScreenOS
Summary
by MITRE
The administrative web services interface in Juniper ScreenOS before 6.3.0r21 allows remote attackers to cause a denial of service (reboot) via a crafted SSL packet.
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Analysis
by VulDB Data Team • 07/25/2022
The vulnerability identified as CVE-2016-1268 represents a critical denial of service flaw within Juniper ScreenOS operating systems prior to version 6.3.0r21. This issue specifically targets the administrative web services interface, which serves as a primary management endpoint for network security devices. The vulnerability manifests through a crafted SSL packet that, when processed by the affected system, triggers an unintended reboot of the device. This flaw significantly impacts network availability and operational continuity, as administrators lose access to their security infrastructure during the reboot process. The attack vector is particularly concerning because it requires no authentication, making it accessible to any remote attacker who can establish SSL connections to the device's management interface.
The technical root cause of this vulnerability lies in inadequate input validation within the SSL packet processing mechanism of the administrative web services component. When the system receives a specially crafted SSL packet, the parsing logic fails to properly handle malformed or unexpected data structures, leading to memory corruption or stack overflow conditions. This results in the operating system kernel crashing and subsequently triggering an automatic reboot of the device. The vulnerability demonstrates poor error handling practices and insufficient bounds checking in the SSL implementation, which are fundamental security principles that should prevent such conditions from occurring. According to CWE classification, this vulnerability maps to CWE-129, which describes improper validation of array indices, and CWE-248, which covers exposure of an exception error to an attacker.
The operational impact of CVE-2016-1268 extends beyond simple service disruption, as it can be leveraged to create persistent availability issues within network security infrastructures. Organizations relying on Juniper firewalls for network protection face significant risks when this vulnerability remains unpatched, as attackers can repeatedly exploit it to maintain persistent denial of service conditions. The vulnerability affects both IPv4 and IPv6 management interfaces, making it particularly dangerous for modern network environments where multiple protocols are supported. Network administrators may experience complete loss of management access during reboot cycles, potentially leaving critical security policies unenforceable. This type of vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a classic example of how improper input validation can lead to system compromise.
Mitigation strategies for CVE-2016-1268 primarily focus on immediate patch deployment to upgrade affected ScreenOS versions to 6.3.0r21 or later. Organizations should also implement network segmentation to limit access to management interfaces, utilize firewall rules to restrict SSL traffic to trusted sources, and establish monitoring systems to detect unusual reboot patterns. Additional defensive measures include disabling unnecessary management services, implementing multi-factor authentication for administrative access, and maintaining detailed audit logs of management interface activity. Network administrators should also consider implementing intrusion detection systems that can identify and alert on suspicious SSL packet patterns that may indicate exploitation attempts. The vulnerability highlights the importance of regular security updates and comprehensive vulnerability management programs, as it demonstrates how seemingly minor input validation flaws can result in significant operational impacts. Organizations should also review their incident response procedures to ensure rapid detection and recovery from such denial of service events.