CVE-2017-6451 in ntp
Summary
by MITRE
The mx4200_send function in the legacy MX4200 refclock in NTP before 4.2.8p10 and 4.3.x before 4.3.94 does not properly handle the return value of the snprintf function, which allows local users to execute arbitrary code via unspecified vectors, which trigger an out-of-bounds memory write.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 11/15/2022
The vulnerability identified as CVE-2017-6451 affects the Network Time Protocol implementation within the legacy MX4200 refclock functionality of NTP versions prior to 4.2.8p10 and 4.3.x versions prior to 4.3.94. This flaw resides in the mx4200_send function which handles communication with MX4200 reference clocks, commonly used in precision time synchronization applications within network infrastructure. The vulnerability represents a critical security weakness that can be exploited by local attackers to achieve arbitrary code execution, making it particularly dangerous in environments where NTP services are running with elevated privileges.
The technical root cause of this vulnerability stems from improper handling of the snprintf function return value within the mx4200_send function. The snprintf function returns the number of characters that would have been written to the buffer if there was sufficient space, rather than just indicating success or failure. When this return value is not properly checked, an attacker can manipulate input data to cause the function to write beyond the allocated buffer boundaries. This leads to an out-of-bounds memory write condition that can be leveraged to overwrite critical memory locations and potentially execute malicious code with the privileges of the NTP process.
This vulnerability operates under the context of local privilege escalation since attackers need to have access to the system to exploit it, but the impact is severe because NTP services typically run with elevated privileges. The out-of-bounds memory write can corrupt program execution flow, leading to arbitrary code execution, denial of service, or information disclosure. The vulnerability is particularly concerning in network infrastructure environments where NTP servers are critical components and where local access might be gained through various attack vectors such as compromised user accounts or misconfigured services.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in C programming environments. The ATT&CK framework categorizes this as a privilege escalation technique through local exploitation, potentially leading to persistent access within the compromised system. The vulnerability demonstrates the critical importance of proper error handling and input validation in security-critical code, particularly in time synchronization services that form the backbone of network operations and security monitoring systems.
The recommended mitigation strategy involves upgrading to NTP versions 4.2.8p10 or later for the 4.2.x series, or 4.3.94 or later for the 4.3.x series, where the snprintf return value handling has been corrected. System administrators should also implement proper access controls to limit local user privileges and consider network segmentation to reduce the attack surface. Additionally, monitoring for unusual NTP behavior and implementing intrusion detection systems can help identify potential exploitation attempts. Organizations should conduct thorough testing of the updated NTP versions in their specific environments to ensure compatibility with existing time synchronization infrastructure while addressing the security vulnerability.