CVE-2015-5146 in ntpd
Summary
by MITRE
ntpd in ntp before 4.2.8p3 with remote configuration enabled allows remote authenticated users with knowledge of the configuration password and access to a computer entrusted to perform remote configuration to cause a denial of service (service crash) via a NULL byte in a crafted configuration directive packet.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 06/28/2022
The vulnerability identified as CVE-2015-5146 affects the Network Time Protocol daemon (ntpd) in versions prior to 4.2.8p3, specifically when remote configuration functionality is enabled. This issue represents a critical security flaw that enables remote authenticated attackers to induce a denial of service condition through a carefully crafted configuration directive packet containing a NULL byte. The vulnerability exists within the ntpd implementation that handles remote configuration commands, creating a potential attack vector for disrupting time synchronization services across networked systems. The flaw is particularly concerning because it requires only knowledge of the configuration password and access to a computer that has been entrusted with performing remote configuration operations, making it exploitable in environments where proper access controls may be insufficient.
The technical root cause of this vulnerability stems from inadequate input validation within the ntpd remote configuration handler. When a crafted configuration directive packet containing a NULL byte is processed, the system fails to properly sanitize or reject the malformed input, leading to a buffer overflow condition or memory corruption that ultimately results in the service crashing. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers stack-based buffer overflow issues. The vulnerability manifests as a service crash rather than a more sophisticated exploit, but the impact is significant as it can be leveraged to disrupt time synchronization across critical network infrastructure components that depend on accurate timekeeping for security operations, logging, and authentication mechanisms.
The operational impact of CVE-2015-5146 extends beyond simple service disruption, as time synchronization is fundamental to many security protocols and network operations. When ntpd crashes due to this vulnerability, it can cause cascading failures throughout networked systems that rely on consistent timekeeping for proper operation. This includes authentication systems that depend on time-based tokens, logging systems that require synchronized timestamps, and network security devices that perform time-sensitive operations. The vulnerability can be exploited as part of a broader attack strategy to disable critical network services, potentially providing attackers with additional opportunities to establish persistence or conduct further reconnaissance activities. According to ATT&CK framework, this vulnerability could be categorized under T1499.004 for network denial of service and T1566.001 for spearphishing with social engineering, as it represents a method of service disruption that can be leveraged in various attack scenarios.
Mitigation strategies for CVE-2015-5146 should focus on immediate patching of affected ntpd installations to version 4.2.8p3 or later, which includes proper input validation for configuration directive packets. Organizations should also implement network segmentation to limit access to systems running ntpd with remote configuration enabled, ensuring that only authorized personnel can access these functions. Additional protective measures include implementing strict access controls for configuration passwords, monitoring network traffic for suspicious configuration directive packets, and maintaining comprehensive logging of configuration changes to detect potential exploitation attempts. Security teams should also consider disabling remote configuration features entirely when not required, as this eliminates the attack surface associated with this vulnerability. Regular vulnerability assessments and security audits should be conducted to identify systems running outdated ntp versions and ensure proper security configurations are maintained throughout the network infrastructure.