CVE-2014-3309 in IOS
Summary
by MITRE
The NTP implementation in Cisco IOS and IOS XE does not properly support use of the access-group command for a "deny all" configuration, which allows remote attackers to bypass intended restrictions on time synchronization via a standard query, aka Bug ID CSCuj66318.
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Analysis
by VulDB Data Team • 12/17/2024
The vulnerability identified as CVE-2014-3309 represents a critical access control flaw within Cisco IOS and IOS XE network operating systems that affects the Network Time Protocol implementation. This issue specifically manifests when administrators attempt to configure strict access controls using the access-group command to restrict NTP traffic, creating a scenario where the security policy fails to properly enforce the intended "deny all" restrictions. The flaw allows unauthorized remote attackers to circumvent these security measures and establish time synchronization connections despite explicit configuration directives designed to prevent such access.
The technical root cause of this vulnerability lies in the improper handling of NTP access control lists within the Cisco IOS and IOS XE software implementations. When administrators configure access-group commands to deny all NTP traffic and subsequently attempt to allow specific sources, the system fails to properly validate and enforce these restrictions during standard NTP query operations. This creates a bypass mechanism where legitimate NTP queries from unauthorized sources can succeed despite the configured access restrictions, effectively undermining the network's time synchronization security posture. The vulnerability specifically affects the NTP implementation's handling of access-group directives, where the system does not properly differentiate between authorized and unauthorized NTP query sources during the standard query processing phase.
The operational impact of this vulnerability extends beyond simple network access control violations, as it can enable attackers to manipulate network time synchronization services and potentially compromise the integrity of time-sensitive network operations. Attackers can leverage this flaw to perform time-based attacks, including man-in-the-middle scenarios where they can synchronize their systems with the affected network devices while maintaining unauthorized access to the NTP service. This vulnerability can also facilitate broader network reconnaissance efforts, as attackers can use the NTP service to gather information about network topology and device configurations while remaining undetected by standard access control mechanisms. The implications are particularly severe in environments where precise time synchronization is critical for security operations, such as those utilizing time-stamped logging, certificate validation, or network-based intrusion detection systems that rely on synchronized time sources.
Organizations affected by CVE-2014-3309 should implement immediate mitigations including applying the relevant Cisco security patches and updates, reviewing existing NTP access control configurations to ensure proper implementation of access lists, and implementing additional network segmentation measures to limit exposure. The vulnerability aligns with CWE-284, which describes improper access control issues in software implementations, and can be categorized under ATT&CK technique T1071.004 for application layer protocol usage. Network administrators should also consider implementing additional monitoring and logging of NTP traffic to detect anomalous access patterns and ensure that access control policies are properly enforced across all network devices. The security community has classified this as a medium to high severity vulnerability due to its potential for enabling unauthorized access to network time synchronization services and its ability to bypass standard network security controls.