CVE-2007-4646 in Hexamail Server
Summary
by MITRE
Buffer overflow in the pop3 service in Hexamail Server 3.0.0.001 Lite allows remote attackers to cause a denial of service (daemon crash) and probably execute arbitrary code via a long USER command.
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Analysis
by VulDB Data Team • 10/03/2024
The vulnerability identified as CVE-2007-4646 represents a critical buffer overflow flaw within the pop3 service component of Hexamail Server version 3.0.0.001 Lite. This security weakness resides in the handling of USER commands, which are fundamental elements of the post office protocol version 3 communication framework. The flaw manifests when the server processes excessively long USER command inputs without proper input validation or boundary checking mechanisms. The buffer overflow occurs because the application fails to adequately constrain the length of user-supplied data before copying it into fixed-size memory buffers, creating an exploitable condition that can be leveraged by remote attackers to compromise system integrity.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where insufficient input sanitization allows malicious actors to overwrite adjacent memory locations within the pop3 service daemon process. When a remote attacker sends a specially crafted USER command containing an excessive number of characters, the server's memory management fails to properly handle the overflow condition, resulting in unpredictable behavior that can lead to daemon crashes or potentially allow code execution. This flaw operates at the application layer and specifically targets the mail server's authentication mechanism, making it particularly dangerous as it can be exploited without requiring prior authentication credentials.
The operational impact of CVE-2007-4646 extends beyond simple denial of service conditions to potentially enable remote code execution, which represents a severe security compromise. The daemon crash scenario immediately disrupts email services for all users connected to the affected mail server, causing significant business disruption and potential data loss. However, the more concerning aspect of this vulnerability is the potential for arbitrary code execution, which would allow attackers to gain unauthorized control over the mail server system. This could enable attackers to install backdoors, exfiltrate email data, modify server configurations, or use the compromised server as a pivot point for further attacks within the network infrastructure.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation that violates fundamental security principles. The attack vector follows ATT&CK technique T1203, which involves exploiting vulnerabilities in network services to gain system access. Organizations running Hexamail Server 3.0.0.001 Lite are particularly vulnerable as this flaw affects the core mail service functionality and provides multiple attack paths for adversaries. The vulnerability demonstrates poor defensive programming practices and highlights the critical importance of implementing robust input validation and memory management controls in server applications.
Mitigation strategies for CVE-2007-4646 should prioritize immediate patching of the Hexamail Server software to the latest available version that addresses this specific buffer overflow vulnerability. Network administrators should implement strict input validation at the network perimeter using intrusion prevention systems and firewalls to limit the exposure of vulnerable services. Additionally, implementing application-level monitoring and logging can help detect exploitation attempts and provide early warning of potential attacks. Organizations should also consider implementing network segmentation to limit the potential impact if an attacker successfully exploits this vulnerability, ensuring that even if one server is compromised, the attack cannot easily spread to other critical systems within the organization's infrastructure.