CVE-2000-0907 in EServ
Summary
by MITRE
EServ 2.92 Build 2982 allows remote attackers to cause a denial of service and possibly execute arbitrary commands via long HELO and MAIL FROM commands.
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Analysis
by VulDB Data Team • 05/11/2019
The vulnerability identified as CVE-2000-0907 affects EServ 2.92 Build 2982, a web server and mail server software package that was widely used in the late 1990s and early 2000s. This particular flaw represents a classic buffer overflow condition that occurs within the mail server functionality of the software, specifically when processing incoming SMTP commands. The vulnerability manifests when remote attackers send specially crafted HELO and MAIL FROM commands that exceed the buffer size allocated for processing these parameters. This issue falls under the CWE-121 category of Stack-based Buffer Overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The vulnerability is particularly concerning because it can be exploited without authentication, making it a significant threat to systems running this outdated software version.
The technical exploitation of this vulnerability occurs through the SMTP protocol implementation within EServ, where the software fails to properly validate the length of incoming commands before processing them. When an attacker sends a malformed HELO command containing an excessive number of characters, the server's buffer handling mechanism overflows, potentially causing the application to crash or behave unpredictably. Similarly, the MAIL FROM command vulnerability allows for the same type of buffer overflow attack, though the specific implementation details differ slightly between the two command types. The vulnerability stems from the lack of input validation and proper boundary checking within the mail server component, which is a fundamental security principle that should be implemented in all network services according to industry best practices and security standards.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the buffer overflow can potentially be leveraged to execute arbitrary code on the affected system. When the buffer overflow occurs, it can overwrite critical memory addresses including return addresses and function pointers, which may allow an attacker to redirect program execution flow. This represents a significant escalation from basic denial of service to potential system compromise, as attackers could potentially inject and execute malicious code within the context of the mail server process. The implications are particularly severe given that many systems running EServ were critical infrastructure components that handled sensitive email communications, making them attractive targets for attackers seeking persistent access to network environments.
Mitigation strategies for CVE-2000-0907 should prioritize immediate software updates and patches from the vendor, though given the age of this vulnerability and the software, such patches may no longer be available. Organizations should implement network segmentation and access controls to limit exposure to this vulnerability, particularly by blocking SMTP traffic from untrusted networks and implementing proper firewall rules. The use of intrusion detection systems can help identify exploitation attempts by monitoring for unusual command lengths in SMTP exchanges. Additionally, implementing input validation at network boundaries and deploying application-level firewalls can provide additional layers of protection. According to ATT&CK framework, this vulnerability maps to T1203 - Exploitation for Client Execution and T1499 - Endpoint Denial of Service, highlighting the dual nature of the threat as both a denial of service vector and a potential code execution pathway. Organizations should also consider decommissioning legacy systems running EServ 2.92, as the age of this software combined with known vulnerabilities makes it unsuitable for modern security requirements. The vulnerability demonstrates the critical importance of keeping software updated and maintaining proper security hygiene, as many of the security controls that would have prevented this issue were not in place in the affected systems.