CVE-2018-0055 in Junos
Summary
by MITRE
Receipt of a specially crafted DHCPv6 message destined to a Junos OS device configured as a DHCP server in a Broadband Edge (BBE) environment may result in a jdhcpd daemon crash. The daemon automatically restarts without intervention, but a continuous receipt of crafted DHCPv6 packets could leaded to an extended denial of service condition. This issue only affects Junos OS 15.1 and later. Earlier releases are unaffected by this issue. Devices are only vulnerable to the specially crafted DHCPv6 message if DHCP services are configured. Devices not configured to act as a DHCP server are not vulnerable to this issue. Affected releases are Juniper Networks Junos OS: 15.1 versions prior to 15.1R7-S2; 15.1X49 versions prior to 15.1X49-D160; 15.1X53 versions prior to 15.1X53-D235, 15.1X53-D495; 16.1 versions prior to 16.1R4-S11, 16.1R6-S6, 16.1R7-S2; 16.2 versions prior to 16.2R2-S7; 17.1 versions prior to 17.1R2-S9; 17.2 versions prior to 17.2R2-S6; 17.3 versions prior to 17.3R3-S1; 17.4 versions prior to 17.4R1-S5; 18.1 versions prior to 18.1R2-S3; 18.2 versions prior to 18.2R1-S2; 18.2X75 versions prior to 18.2X75-D20.
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Analysis
by VulDB Data Team • 05/25/2023
The vulnerability described in CVE-2018-0055 represents a critical denial of service weakness within Junos OS devices operating as DHCPv6 servers in Broadband Edge environments. This flaw specifically targets the jdhcpd daemon responsible for handling DHCPv6 protocol operations, creating a scenario where maliciously crafted DHCPv6 packets can trigger daemon crashes. The issue manifests when the daemon receives specially constructed packets that exploit memory handling or parsing mechanisms within the DHCPv6 implementation. The vulnerability demonstrates characteristics consistent with CWE-121, heap-based buffer overflow, where improper input validation leads to memory corruption that causes process termination. The attack vector is particularly concerning as it requires no authentication and can be executed remotely, making it accessible to any attacker with network access to the affected device.
The operational impact of this vulnerability extends beyond simple daemon restarts, creating potential for sustained disruption in network services. While the jdhcpd daemon automatically restarts following a crash, the continuous receipt of crafted packets can maintain the denial of service condition indefinitely. This behavior aligns with ATT&CK technique T1499.004, which covers network disruption through resource exhaustion or process termination. The vulnerability affects a broad range of Junos OS versions including 15.1 through 18.2 releases, with specific patch levels identified for each version family. Network administrators must understand that this vulnerability operates at the protocol level, exploiting fundamental parsing and memory management functions within the DHCPv6 server implementation rather than application-level flaws. The automatic restart mechanism provides some resilience but does not eliminate the service disruption impact.
Devices remain vulnerable only when explicitly configured to function as DHCP servers, making proper network segmentation and access control critical defensive measures. This configuration dependency aligns with the principle of least privilege, where unnecessary services should be disabled to reduce attack surface. The vulnerability's impact is particularly severe in Broadband Edge environments where DHCPv6 services are commonly deployed to manage network access for residential and business customers. Organizations should consider implementing network monitoring to detect unusual DHCPv6 traffic patterns that might indicate exploitation attempts. The affected releases demonstrate that this issue has persisted across multiple Junos OS version branches, suggesting a fundamental flaw in the DHCPv6 implementation that required multiple patch cycles to address. Network operators should prioritize patching based on their specific deployment scenarios, focusing on devices that actually serve DHCPv6 traffic rather than those in passive monitoring roles.
Mitigation strategies should include immediate deployment of vendor patches for affected Junos OS versions, as well as network-level controls to filter suspicious DHCPv6 traffic. The automatic restart behavior provides some protection against sustained attacks but does not prevent the initial disruption. Network administrators should implement monitoring solutions to detect repeated daemon crashes and correlate these events with network traffic patterns. Configuration reviews should ensure that DHCPv6 services are only enabled where absolutely necessary, following the principle that any network service not required for operations should be disabled. The vulnerability's characteristics suggest that implementing rate limiting or packet filtering for DHCPv6 traffic could provide additional protection, particularly in environments where the attack surface is difficult to control. Organizations should also consider implementing intrusion detection systems capable of identifying the specific packet patterns associated with this vulnerability to enable proactive threat hunting activities.