CVE-2018-0683 in Denbun
Summary
by MITRE
Buffer overflow in Denbun by NEOJAPAN Inc. (Denbun POP version V3.3P R4.0 and earlier, Denbun IMAP version V3.3I R4.0 and earlier) allows remote attackers to execute arbitrary code or cause a denial-of-service (DoS) condition via Cookie data.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 04/13/2020
The vulnerability identified as CVE-2018-0683 represents a critical buffer overflow flaw affecting Denbun by NEOJAPAN Inc. This security weakness manifests in both Denbun POP and Denbun IMAP versions up to V3.3P R4.0 and V3.3I R4.0 respectively, creating a significant attack surface for malicious actors. The vulnerability specifically targets the handling of Cookie data within these email client applications, which are widely used for accessing email services through POP and IMAP protocols. The buffer overflow occurs when the application fails to properly validate or limit the size of incoming cookie data, allowing attackers to exceed allocated memory boundaries and potentially execute arbitrary code or trigger denial-of-service conditions. This flaw directly corresponds to CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack vector is particularly concerning as it enables remote code execution, making it a high-severity threat that can be exploited without requiring local access or authentication.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the cookie processing subsystem of the Denbun applications. When the software receives cookie data from email servers, it does not properly enforce size limitations or perform adequate bounds checking before copying data into fixed-size buffers. This creates an exploitable condition where an attacker can craft malicious cookie data that exceeds the allocated buffer space, causing memory corruption that can be leveraged for code execution. The flaw operates under the principle of stack-based or heap-based buffer overflow depending on implementation details, but the core issue remains the same - insufficient boundary checking allows memory overwrite conditions. From an operational perspective, this vulnerability affects email clients that rely on these specific versions of Denbun software, potentially compromising thousands of systems that use these applications for email access. The impact extends beyond simple code execution to include complete system compromise when combined with other exploitation techniques, making it a prime target for advanced persistent threat actors.
The operational implications of CVE-2018-0683 are severe and multifaceted, affecting both enterprise and individual users who depend on these email applications. Attackers can exploit this vulnerability to gain unauthorized access to systems, execute malicious code, and potentially establish persistent backdoors within network environments. The denial-of-service component of this vulnerability can also be leveraged to disrupt email services, causing significant operational downtime for organizations. From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059 which covers command and scripting interpreter usage, and T1203 which describes legitimate credentials used for lateral movement. The vulnerability's remote exploitability means that attackers can target systems from outside the network perimeter, making it particularly dangerous in environments where email clients are used to access corporate email systems. Organizations using affected versions of Denbun software face potential data breaches, system compromise, and service disruption that can have cascading effects throughout their IT infrastructure.
Mitigation strategies for CVE-2018-0683 should prioritize immediate software updates from NEOJAPAN Inc. to address the buffer overflow condition in affected versions of Denbun POP and IMAP applications. System administrators should implement network segmentation to limit exposure of vulnerable systems and deploy intrusion detection systems to monitor for suspicious cookie data patterns. Additional protective measures include implementing web application firewalls that can filter malicious cookie content, disabling unnecessary email protocols when possible, and conducting regular vulnerability assessments to identify other potential buffer overflow conditions within the email infrastructure. Organizations should also establish incident response procedures specifically addressing remote code execution vulnerabilities and ensure that all email clients are regularly updated with the latest security patches. The remediation process must include thorough testing of updated software versions to ensure that the vulnerability is fully addressed without introducing new compatibility issues. Furthermore, security monitoring should be enhanced to detect potential exploitation attempts through analysis of cookie data patterns that might indicate attempted buffer overflow attacks, providing early warning capabilities for organizations that cannot immediately patch their systems.