CVE-2001-0776 in Mailserver
Summary
by MITRE
Buffer overflow in DynFX MailServer version 2.10 allows remote attackers to conduct a denial of service via a long username to the POP3 service.
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Analysis
by VulDB Data Team • 05/31/2019
The vulnerability identified as CVE-2001-0776 represents a critical buffer overflow flaw within DynFX MailServer version 2.10 that specifically affects the POP3 service implementation. This security weakness arises from insufficient input validation mechanisms within the mail server's authentication process, where the system fails to properly sanitize user-provided credentials before processing them. The flaw manifests when an attacker submits an excessively long username string to the POP3 service, causing the application to overwrite adjacent memory regions beyond the allocated buffer boundaries. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, which is particularly dangerous as it can lead to arbitrary code execution or system instability. The POP3 protocol implementation in DynFX MailServer version 2.10 does not enforce proper bounds checking on username inputs, creating a pathway for malicious actors to exploit the memory corruption vulnerability.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the buffer overflow can potentially allow remote attackers to execute arbitrary code on the affected system. When a maliciously crafted username exceeds the buffer size limits, the overflow can overwrite critical program execution data including return addresses and function pointers, which may enable an attacker to redirect program flow or inject malicious instructions. This vulnerability specifically targets the POP3 service which is commonly used for email retrieval and authentication, making it a prime target for attackers seeking to compromise email infrastructure. The remote nature of the attack means that exploitation can occur without requiring physical access to the system, and the vulnerability affects all versions of DynFX MailServer up to and including version 2.10, indicating a widespread exposure across affected deployments.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly under the initial access and execution phases where attackers leverage service vulnerabilities to gain system control. The attack vector specifically corresponds to ATT&CK technique T1190 which involves exploiting vulnerabilities in remote services, and the subsequent execution phase may involve T1059 for command and control operations. Organizations running DynFX MailServer version 2.10 face significant risk as this vulnerability can be exploited by automated scanning tools to identify vulnerable systems across the internet. The lack of input validation and proper error handling in the POP3 service creates a persistent threat that can be leveraged for both disruptive denial of service attacks and more sophisticated compromise attempts.
Mitigation strategies for CVE-2001-0776 should focus on immediate patch deployment from the vendor, which would address the buffer overflow through proper input validation and memory boundary checks. System administrators should implement network segmentation to limit access to POP3 services, particularly restricting access to trusted IP ranges and implementing firewall rules that monitor for unusually long username submissions. Additionally, deploying intrusion detection systems that can identify suspicious authentication patterns and implementing logging controls that capture anomalous username lengths can provide early warning of exploitation attempts. Organizations should also consider implementing multi-factor authentication mechanisms and regular security assessments to identify similar vulnerabilities in other mail server implementations. The vulnerability underscores the importance of proper software security practices including input validation, bounds checking, and regular security updates as recommended by industry standards such as those outlined in the OWASP Top Ten and NIST cybersecurity guidelines.