CVE-2014-0021 in Chrony
Summary
by MITRE
Chrony before 1.29.1 has traffic amplification in cmdmon protocol
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Analysis
by VulDB Data Team • 12/22/2024
The vulnerability identified as CVE-2014-0021 affects the chrony time synchronization daemon version 1.29.1 and earlier, presenting a significant traffic amplification issue within the cmdmon protocol. This flaw enables attackers to exploit the command monitoring interface to generate disproportionately large responses relative to the initial request size, creating a potential vector for distributed denial-of-service attacks. The cmdmon protocol serves as a command interface for remote management of chrony servers, allowing administrators to query system status, modify configurations, and monitor time synchronization metrics. However, the implementation contains a critical design flaw that permits malicious actors to craft specific requests that trigger massive response payloads from the target system.
The technical implementation of this vulnerability stems from insufficient input validation and response size management within the cmdmon protocol handler. When a client sends a command request to a chrony server with specific parameters, the server processes the request and generates a response containing detailed system information, configuration data, and potentially sensitive metrics. The flaw occurs because the response generation logic does not properly limit the size of returned data based on the input request, allowing an attacker to request information that results in responses many times larger than the original query. This amplification factor can reach several hundred times the original packet size, making it particularly dangerous for network infrastructure with limited bandwidth capacity. The vulnerability specifically impacts the command monitoring interface that is typically accessible over network ports, enabling remote exploitation without requiring authentication for the amplification attack itself.
The operational impact of CVE-2014-0021 extends beyond simple bandwidth consumption, as it creates a scalable vector for network-level attacks that can overwhelm target systems and their network connections. Attackers can leverage this vulnerability to amplify their network traffic by hundreds of times, making it possible to generate massive amounts of network traffic from relatively small attack packets. This characteristic aligns with common traffic amplification attack patterns that are frequently categorized under the MITRE ATT&CK framework within the T1498 category for Network Denial of Service. The vulnerability affects systems that expose chrony's cmdmon interface to untrusted networks or the internet, particularly those running older versions of chrony where the fix was not yet implemented. Organizations using chrony for time synchronization in environments where network security is not properly segmented may find their systems vulnerable to this type of attack, potentially leading to service disruption, bandwidth exhaustion, and cascading failures in network infrastructure.
The recommended mitigation strategies for CVE-2014-0021 involve immediate deployment of chrony version 1.29.1 or later, which includes patches addressing the traffic amplification issue. Network administrators should also implement proper firewall rules to restrict access to the cmdmon protocol interface, limiting it to trusted management networks only. The fix typically involves implementing response size limits and input validation checks within the cmdmon protocol handler to prevent the generation of oversized responses. Additionally, organizations should consider disabling the cmdmon protocol entirely if it is not required for operational purposes, as this removes the attack surface entirely. The vulnerability demonstrates the importance of proper input validation and output size management in network services, principles that align with CWE-129 and CWE-131 categories related to buffer overflow and integer overflow conditions. Network security monitoring should also be enhanced to detect unusual traffic patterns that may indicate exploitation attempts, as the amplification effect can be used to mask the true source of attacks while generating massive network load.