CVE-2017-2340 in Junos M
Summary
by MITRE
On Juniper Networks Junos OS 15.1 releases from 15.1R3 to 15.1R4, 16.1 prior to 16.1R3, on M/MX platforms where Enhanced Subscriber Management for DHCPv6 subscribers is configured, a vulnerability in processing IPv6 ND packets originating from subscribers and destined to M/MX series routers can result in a PFE (Packet Forwarding Engine) hang or crash.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability described in CVE-2017-2340 represents a critical flaw in Juniper Networks Junos OS affecting specific router platforms including M-series and MX-series devices. This issue manifests when Enhanced Subscriber Management for DHCPv6 subscribers is configured on routers running Junos OS versions 15.1R3 through 15.1R4 and 16.1 prior to 16.1R3. The vulnerability specifically targets the processing of IPv6 Neighbor Discovery (ND) packets that originate from subscribers and are destined for the router infrastructure. From a security perspective, this represents a potential denial of service condition that could severely impact network operations and availability.
The technical implementation of this vulnerability resides within the Packet Forwarding Engine's handling of IPv6 Neighbor Discovery packets. When these packets are processed by the PFE in routers with the specified DHCPv6 subscriber management configuration, the system experiences a hang or crash condition. This flaw operates at the network protocol processing level where IPv6 Neighbor Discovery messages are improperly handled, leading to system instability. The vulnerability is categorized under CWE-121 as a buffer overflow condition that occurs during packet processing, though the specific implementation likely involves improper memory handling or state management within the IPv6 processing modules.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network reliability and availability. When the PFE hangs or crashes, network traffic processing ceases on affected router interfaces, creating routing black holes that can isolate network segments or cause complete service outages. The vulnerability affects routers that are actively managing DHCPv6 subscribers, which typically includes service provider networks where subscriber management is critical for maintaining connectivity. This makes the impact particularly severe in production environments where network stability is paramount. The vulnerability's presence in multiple release versions indicates it was a persistent issue that required multiple patches to address properly.
Organizations affected by this vulnerability should prioritize immediate remediation through official Juniper security patches and updates. The recommended mitigation strategy involves upgrading to Junos OS versions that contain the fix for this specific issue, typically found in releases 15.1R5, 16.1R3, and later versions. Network administrators should also consider implementing monitoring solutions to detect potential exploitation attempts and establish incident response procedures for handling PFE crashes. From an ATT&CK framework perspective, this vulnerability maps to techniques involving denial of service and system compromise through protocol manipulation, potentially enabling adversaries to create persistent network disruptions that could be leveraged for further attacks. The vulnerability's nature as a packet processing flaw makes it particularly attractive to attackers seeking to disrupt network services, as it requires minimal privileges and can cause significant operational impact.