CVE-2001-0414 in ntpd
Summary
by MITRE
Buffer overflow in ntpd ntp daemon 4.0.99k and earlier (aka xntpd and xntp3) allows remote attackers to cause a denial of service and possibly execute arbitrary commands via a long readvar argument.
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability identified as CVE-2001-0414 represents a critical buffer overflow flaw within the Network Time Protocol daemon version 4.0.99k and earlier releases, commonly known as ntpd or xntpd. This daemon serves as the core time synchronization service in Unix-like operating systems and is responsible for maintaining accurate system time across networked environments. The affected versions of the daemon implement a command processing mechanism that fails to properly validate input length when handling readvar arguments, creating a exploitable condition that can be leveraged by remote attackers to compromise system integrity.
The technical implementation of this vulnerability stems from insufficient bounds checking within the ntpd daemon's argument parsing routine. When processing a maliciously crafted readvar command with an excessively long argument string, the daemon's internal buffer allocation mechanism fails to accommodate the oversized input, leading to memory corruption. This buffer overflow condition occurs in the context of network protocol handling where the daemon processes time synchronization commands from remote clients. The flaw specifically manifests when the ntpd daemon receives a readvar request containing more data than the allocated buffer space, causing adjacent memory regions to be overwritten and potentially corrupting critical program execution structures.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution, making it particularly dangerous for systems that rely on ntpd for time synchronization. Attackers can exploit this condition to cause the daemon to crash, resulting in time synchronization failures that can affect system logging, authentication mechanisms, and network services that depend on accurate timestamps. In more severe scenarios, the buffer overflow can be manipulated to inject and execute arbitrary code within the context of the ntpd process, potentially providing attackers with elevated privileges and persistent access to the compromised system. The vulnerability affects systems where ntpd is running with sufficient privileges to execute commands, creating a pathway for attackers to escalate their access and compromise the broader network infrastructure.
Mitigation strategies for this vulnerability require immediate patching of affected ntpd installations to version 4.1.0 or later, which contains the necessary buffer overflow protections and input validation mechanisms. System administrators should also implement network-level restrictions to limit access to ntpd services, particularly disabling unnecessary network interfaces and restricting readvar command usage. The implementation of proper input validation and bounds checking mechanisms aligns with common weakness enumeration standard CWE-121, which addresses buffer overflow conditions in heap and stack memory allocations. Additionally, this vulnerability relates to attack technique T1105 in the ATT&CK framework, which describes the use of remote access tools and exploitation of service vulnerabilities for persistent system compromise. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected ntpd versions and implement network segmentation to reduce the attack surface while maintaining proper time synchronization across their infrastructure.