CVE-2017-6458 in ntp
Summary
by MITRE
Multiple buffer overflows in the ctl_put* functions in NTP before 4.2.8p10 and 4.3.x before 4.3.94 allow remote authenticated users to have unspecified impact via a long variable.
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Analysis
by VulDB Data Team • 09/14/2020
The vulnerability identified as CVE-2017-6458 represents a critical buffer overflow flaw affecting the Network Time Protocol implementation in versions prior to 4.2.8p10 and 4.3.x before 4.3.94. This issue resides within the ctl_put* functions which handle control message processing in the NTP daemon. The vulnerability specifically manifests when the NTP service receives a malformed control message containing an excessively long variable that exceeds the allocated buffer space, creating potential for arbitrary code execution or service disruption. The flaw affects systems that utilize NTP for time synchronization, making it particularly dangerous in enterprise environments where time coordination is critical for security operations and network services.
The technical implementation of this vulnerability stems from inadequate input validation within the control message handling routines of the NTP daemon. When the ctl_put* functions process incoming control messages, they fail to properly bounds-check the length of variable-length data fields, allowing attackers to craft malicious packets that exceed predetermined buffer limits. This buffer overflow condition can be exploited by authenticated remote attackers who have access to the NTP control interface, typically through legitimate NTP client connections or network monitoring tools. The vulnerability is classified as a classic stack-based buffer overflow according to CWE-121, with potential for privilege escalation and system compromise when successful exploitation occurs.
The operational impact of CVE-2017-6458 extends beyond simple denial of service scenarios, as demonstrated by the unspecified nature of the potential consequences. Attackers could leverage this vulnerability to execute arbitrary code on affected systems, potentially gaining root privileges or disrupting critical time synchronization services that underpin numerous security protocols including kerberos authentication, certificate validation, and network logging systems. The vulnerability affects NTP implementations across multiple platforms and architectures, with particular concern for systems where NTP servers are exposed to untrusted networks or where control access is not properly restricted. Given that many enterprise networks rely on accurate timekeeping for security event correlation and compliance requirements, the compromise of NTP services can have cascading effects on overall network security posture.
Mitigation strategies for this vulnerability include immediate patching of affected NTP implementations to versions 4.2.8p10 or 4.3.94 and later, which contain proper input validation and buffer size checking mechanisms. Network administrators should also implement strict access controls to NTP control interfaces, limiting access to trusted management systems and implementing network segmentation to prevent unauthorized access. The vulnerability aligns with ATT&CK technique T1071.004 for application layer protocol usage and T1068 for exploit for privilege escalation. Additional defensive measures include monitoring for unusual NTP control message patterns, implementing intrusion detection systems to detect malformed control packets, and conducting regular vulnerability assessments of time synchronization services. Organizations should also consider implementing time synchronization redundancy and monitoring to detect potential compromise of time services that could indicate exploitation attempts.