CVE-2016-1276 in Junos
Summary
by MITRE
Juniper Junos OS before 12.1X46-D50, 12.1X47 before 12.1X47-D23, 12.3X48 before 12.3X48-D25, and 15.1X49 before 15.1X49-D40 on a High-End SRX-Series chassis system with one or more Application Layer Gateways (ALGs) enabled allow remote attackers to cause a denial of service (CPU consumption, fab link failure, or flip-flop failovers) via vectors related to in-transit traffic matching ALG rules.
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Analysis
by VulDB Data Team • 09/02/2022
The vulnerability identified as CVE-2016-1276 affects Juniper Junos OS versions prior to specific patch releases on High-End SRX-Series chassis systems that have Application Layer Gateways (ALGs) enabled. This issue represents a significant security weakness that can be exploited remotely to cause system-wide denial of service conditions. The vulnerability specifically targets the handling of in-transit traffic that matches ALG rules, which are designed to inspect and modify application-layer traffic for features like NAT traversal and protocol translation.
The technical flaw manifests when ALG modules process incoming network traffic that matches their rule sets, causing excessive CPU utilization that can lead to system instability. This occurs because the ALG implementations fail to properly handle certain traffic patterns, resulting in infinite loops or excessive resource consumption during packet processing. The vulnerability is particularly dangerous because it can trigger multiple forms of system degradation including CPU exhaustion, fabric link failures, and flip-flop failovers that disrupt normal network operations. These conditions can persist until manual intervention occurs or the system reaches a complete failure state.
The operational impact of this vulnerability is severe for organizations relying on SRX-Series firewalls with ALG functionality enabled. Network availability is compromised as legitimate traffic processing becomes impossible due to the excessive CPU load generated by the malicious traffic patterns. Fabric link failures can cause complete network segmentation, while flip-flop failovers result in unnecessary service interruptions and potential data loss during failover transitions. The remote exploitation capability means that attackers can trigger these conditions without requiring physical access or local network presence, making the vulnerability particularly dangerous for perimeter security devices.
Organizations should immediately implement mitigations including applying the relevant Juniper security patches that address the ALG processing flaws in the affected Junos OS versions. The vulnerability maps to CWE-775, which describes the improper handling of file operations without proper resource management, and aligns with ATT&CK technique T1499.002 for network denial of service attacks. Network administrators should also consider disabling ALG functionality if it is not required for business operations, as this provides an immediate workaround to prevent exploitation. Additionally, implementing traffic monitoring and anomaly detection systems can help identify the characteristic patterns associated with this vulnerability before complete system failure occurs.