CVE-2015-7854 in ntpd
Summary
by MITRE
Buffer overflow in the password management functionality in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote authenticated users to cause a denial of service (daemon crash) or possibly execute arbitrary code via a crafted key file.
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Analysis
by VulDB Data Team • 06/24/2022
The vulnerability identified as CVE-2015-7854 represents a critical buffer overflow flaw within the Network Time Protocol implementation that affects versions 4.2.x prior to 4.2.8p4 and 4.3.x prior to 4.3.77. This issue resides in the password management functionality of the ntpd daemon, which is responsible for maintaining accurate time synchronization across networked systems. The vulnerability specifically manifests when processing crafted key files that contain maliciously constructed data, creating a condition where the daemon fails to properly validate input lengths before copying data into fixed-size buffers.
The technical exploitation of this vulnerability occurs through the manipulation of key files used by the NTP daemon for authentication purposes. When an authenticated remote attacker supplies a specially crafted key file containing oversized data sequences, the buffer overflow condition is triggered during the parsing process. This flaw falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The vulnerability's impact is significant as it can be leveraged to either crash the ntpd daemon, resulting in denial of service for time synchronization services, or potentially execute arbitrary code with the privileges of the ntpd process.
From an operational perspective, this vulnerability poses a substantial risk to network infrastructure relying on NTP services, as it can be exploited by authenticated attackers who have access to the system. The attack vector requires only authentication to the NTP service, which may be accessible through various means including compromised accounts or legitimate administrative access. The potential for remote code execution makes this particularly dangerous in environments where NTP daemons run with elevated privileges. According to ATT&CK framework categorization, this vulnerability maps to T1059.007 for command and scripting interpreter and T1499.004 for network denial of service, as it enables both service disruption and code execution capabilities.
The mitigation strategy for CVE-2015-7854 involves immediate deployment of patched versions of the NTP daemon, specifically upgrading to version 4.2.8p4 or 4.3.77 respectively. System administrators should also implement network segmentation to limit access to NTP services, restrict authentication mechanisms to only trusted entities, and monitor for unusual key file modifications. Additional protective measures include implementing intrusion detection systems to monitor for anomalous NTP traffic patterns and conducting regular security audits of time synchronization infrastructure. Organizations should also consider disabling unnecessary NTP key file processing capabilities and ensuring that only authorized personnel have access to modify NTP configuration files. The vulnerability demonstrates the importance of input validation in network services and highlights the critical nature of maintaining up-to-date security patches in time-critical infrastructure components.