CVE-2019-12567 in Open TFTP Server MT
Summary
by MITRE
Stack-based overflow vulnerability in the logMess function in Open TFTP Server MT 1.65 and earlier allows remote attackers to perform a denial of service or execute arbitrary code via a long TFTP error packet, a different vulnerability than CVE-2018-10387 and CVE-2019-12568.
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Analysis
by VulDB Data Team • 03/16/2024
The vulnerability identified as CVE-2019-12567 represents a critical stack-based buffer overflow within the logMess function of Open TFTP Server MT version 1.65 and earlier. This flaw exists in the handling of TFTP error packets, specifically when processing malformed or excessively long error messages. The vulnerability demonstrates characteristics consistent with CWE-121 Stack-based Buffer Overflow, where insufficient bounds checking allows an attacker to overwrite adjacent stack memory locations. The affected software operates as a TFTP (Trivial File Transfer Protocol) server implementation, making it susceptible to exploitation through network-based attacks targeting the TFTP protocol's error handling mechanisms.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a malicious TFTP error packet containing an abnormally long error message string. When the logMess function processes this malformed packet, it fails to validate the length of the incoming error message before copying it into a fixed-size stack buffer. This oversight creates a condition where the buffer overflow can occur, potentially leading to arbitrary code execution or denial of service. The vulnerability is particularly concerning because it operates at the protocol level, allowing attackers to exploit the server without requiring authentication or prior access to the system. The error packet handling mechanism becomes a vector for memory corruption, where the overflow can overwrite return addresses, function pointers, or other critical stack data structures.
Operationally, this vulnerability presents significant risks to systems running vulnerable versions of Open TFTP Server MT. The potential for remote code execution means that attackers could gain complete control over affected systems, potentially leading to data breaches, system compromise, or further lateral movement within network environments. The denial of service aspect also creates substantial operational impact, as attackers could disrupt legitimate TFTP services and prevent authorized users from transferring files. Organizations relying on TFTP servers for network booting, firmware updates, or other critical operations would face service interruptions and security risks. The vulnerability affects systems where TFTP servers are exposed to untrusted networks, making it particularly dangerous in enterprise environments or public-facing services.
Mitigation strategies for CVE-2019-12567 should prioritize immediate patching of affected systems to the latest available versions of Open TFTP Server MT. Organizations should implement network segmentation to limit exposure of TFTP servers to trusted networks only, reducing the attack surface for remote exploitation attempts. Network monitoring and intrusion detection systems should be configured to detect anomalous TFTP error packet patterns that might indicate exploitation attempts. The implementation of firewall rules to restrict TFTP traffic to necessary network segments can help minimize risk exposure. Additionally, system administrators should consider disabling TFTP services if they are not essential for operations, as this eliminates the attack vector entirely. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of the vulnerable software and ensure proper remediation has been completed across all affected systems.