CVE-2018-7185 in Fujitsu M10-1
Summary
by MITRE
The protocol engine in ntp 4.2.6 before 4.2.8p11 allows a remote attackers to cause a denial of service (disruption) by continually sending a packet with a zero-origin timestamp and source IP address of the "other side" of an interleaved association causing the victim ntpd to reset its association.
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Analysis
by VulDB Data Team • 01/15/2025
The vulnerability described in CVE-2018-7185 affects the Network Time Protocol implementation in ntp versions prior to 4.2.8p11, specifically targeting the protocol engine's handling of timestamp validation. This issue represents a classic denial of service vulnerability that exploits a flaw in how the ntpd daemon processes incoming packets, particularly those with malformed timestamp values. The vulnerability manifests when an attacker sends a specially crafted packet containing a zero-origin timestamp while maintaining the source IP address of the legitimate peer in an interleaved association. This particular attack vector demonstrates a fundamental weakness in the NTP protocol's state management and packet validation mechanisms, where the system fails to properly validate timestamp consistency and association integrity.
The technical flaw stems from the protocol engine's inadequate validation of timestamp values during association processing, specifically when dealing with interleaved associations where multiple peers communicate with the same ntpd instance. When a packet arrives with a zero-origin timestamp and the source IP address matching the "other side" of an existing association, the ntpd daemon incorrectly interprets this as a valid retransmission or legitimate update request. This misinterpretation triggers an association reset mechanism within the daemon, causing it to abandon the existing association and potentially disrupt time synchronization for the affected system. The vulnerability operates at the protocol level, bypassing traditional network security controls and exploiting the inherent assumptions made by the NTP implementation regarding packet legitimacy and timestamp consistency.
From an operational perspective, this vulnerability can cause significant disruption to network time synchronization services, particularly in environments where precise timekeeping is critical for security operations, logging, and distributed system coordination. The denial of service impact extends beyond simple service interruption, as it can lead to cascading failures in systems that depend on synchronized time for authentication, audit trails, and cryptographic operations. Organizations using ntp versions prior to 4.2.8p11 may experience intermittent time synchronization failures, increased network traffic due to repeated association resets, and potential service degradation across their infrastructure. The attack requires minimal resources from the attacker, making it particularly dangerous as it can be exploited by automated tools to systematically disrupt time synchronization services across multiple systems.
The vulnerability aligns with CWE-248, which addresses the exposure of an uninitialized variable or improper state handling in protocol implementations, and demonstrates characteristics consistent with ATT&CK technique T1499.001, which involves network denial of service attacks targeting protocol implementations. Organizations should immediately upgrade to ntp version 4.2.8p11 or later to address this vulnerability, as the fix implements proper timestamp validation and association state management. Additional mitigations include implementing network-level filtering to block malformed NTP packets, deploying intrusion detection systems to monitor for suspicious NTP traffic patterns, and configuring ntpd with appropriate security settings to limit association resets. The incident highlights the importance of robust protocol validation and state management in network services, particularly those critical for infrastructure security and operational continuity.