CVE-2015-7705 in ntpd
Summary
by MITRE
The rate limiting feature in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to have unspecified impact via a large number of crafted requests.
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Analysis
by VulDB Data Team • 06/25/2022
The vulnerability identified as CVE-2015-7705 represents a significant security flaw in the Network Time Protocol implementation across multiple versions of the NTP daemon. This issue specifically targets the rate limiting mechanism that was designed to prevent abuse and protect against denial of service attacks. The vulnerability affects NTP versions 4.x prior to 4.2.8p4 and 4.3.x prior to 4.3.77, indicating a widespread impact across multiple release lines of the protocol implementation. The flaw lies in how the system handles excessive requests, creating a potential attack vector that could allow remote adversaries to manipulate the rate limiting functionality to achieve unspecified but potentially severe consequences.
The technical nature of this vulnerability stems from improper handling of crafted requests within the rate limiting subsystem of the NTP daemon. When subjected to a large volume of specially constructed requests, the rate limiting mechanism fails to properly constrain resource consumption or request processing, potentially leading to resource exhaustion or system instability. This type of vulnerability falls under the category of improper resource management as classified by CWE-400, where the system fails to adequately control resource allocation and usage patterns. The flaw essentially allows attackers to bypass intended rate limiting controls through carefully constructed inputs that exploit implementation gaps in the request processing logic.
From an operational perspective, this vulnerability presents a substantial risk to network infrastructure that relies on NTP for time synchronization services. The unspecified impact could manifest in various ways including denial of service conditions that prevent legitimate time synchronization requests from being processed, increased system resource consumption leading to performance degradation, or potential system crashes that would disrupt time services critical for network operations. The remote nature of the attack means that adversaries do not need physical access to the target system and can exploit this vulnerability from anywhere on the network, making it particularly dangerous for publicly accessible NTP servers. This vulnerability directly relates to the ATT&CK technique T1499.004 for Network Denial of Service and could potentially be leveraged as part of broader attack campaigns targeting network infrastructure.
The mitigation strategy for CVE-2015-7705 requires immediate deployment of patched NTP versions, specifically upgrading to 4.2.8p4 or later for the 4.2.x series and 4.3.77 or later for the 4.3.x series. Organizations should also implement additional network-level protections such as rate limiting at the firewall level, monitoring for unusual request patterns, and implementing intrusion detection systems that can identify potential exploitation attempts. Network administrators should conduct thorough vulnerability assessments to identify all NTP servers within their environment and ensure proper patch management procedures are in place. The fix addresses the core issue by properly implementing rate limiting controls and ensuring that crafted requests are handled appropriately without allowing the system to be overwhelmed by excessive processing demands. Additionally, implementing proper logging and monitoring capabilities will help detect and respond to exploitation attempts while maintaining compliance with security standards such as those outlined in NIST SP 800-53 for system security planning and control implementation.