CVE-2000-0825 in IMail
Summary
by MITRE
Ipswitch Imail 6.0 allows remote attackers to cause a denial of service via a large number of connections in which a long Host: header is sent, which causes a thread to crash.
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Analysis
by VulDB Data Team • 05/11/2019
The vulnerability identified as CVE-2000-0825 affects Ipswitch Imail 6.0, a widely used email server software that was prevalent in enterprise environments during the late 1990s and early 2000s. This particular flaw represents a classic denial of service vulnerability that exploits the server's handling of network connections and header processing. The vulnerability specifically targets the mail server's ability to process incoming connections and parse the Host: header field within HTTP requests, which is a fundamental component of web-based email access protocols. The flaw demonstrates poor input validation and resource management within the email server's thread handling mechanism, creating a scenario where malicious actors can disrupt legitimate service availability.
The technical exploitation of this vulnerability occurs when an attacker sends a large number of concurrent connections to the Imail server while simultaneously including an excessively long Host: header field in each request. This specific implementation flaw causes the server's threading model to fail when processing these malformed requests, leading to thread crashes and subsequent service degradation. The vulnerability operates at the application layer and specifically targets the server's HTTP processing capabilities, which are integral to the web-based administration and access interfaces that Imail provided. The issue stems from insufficient bounds checking on header field lengths, allowing malicious input to overflow buffer structures and trigger thread termination. This type of vulnerability aligns with CWE-122, which describes buffer overflow conditions, and CWE-400, which covers resource exhaustion scenarios. The flaw represents a fundamental weakness in the server's defensive programming practices and demonstrates the importance of proper input sanitization and resource management in network services.
From an operational impact perspective, this vulnerability enables remote attackers to effectively perform denial of service attacks against mail servers running Ipswitch Imail 6.0 without requiring any authentication or privileged access. The attack can be executed from anywhere on the internet, making it particularly dangerous for organizations that expose their email servers to public networks. The service disruption can range from partial degradation to complete unavailability of email services, affecting business communications and potentially causing significant operational downtime. Organizations relying on this email server software would experience immediate and substantial impact on their email infrastructure, potentially affecting thousands of users depending on the size of their organization. The vulnerability also demonstrates how seemingly benign HTTP header processing can become a critical security concern when proper input validation is absent. The attack requires minimal technical expertise to execute and can be automated, making it particularly attractive to attackers seeking to disrupt services. This vulnerability has been categorized under the MITRE ATT&CK framework as a Denial of Service technique, specifically targeting network services and application availability.
The mitigation strategies for CVE-2000-0825 involve multiple layers of defensive measures that address both immediate remediation and long-term security hardening. Organizations should immediately apply the vendor-provided patches or upgrade to newer versions of Ipswitch Imail that address this specific vulnerability. Network-level mitigations include implementing connection rate limiting, firewall rules to restrict access to the affected ports, and intrusion detection systems that can identify and block suspicious connection patterns. The implementation of proper input validation and buffer size limitations on HTTP headers should be enforced at the application level to prevent similar vulnerabilities from occurring in other components. Additionally, system administrators should monitor connection patterns and implement automated alerts for unusual traffic spikes that might indicate exploitation attempts. The vulnerability highlights the importance of regular security assessments and vulnerability management processes, as well as the need for organizations to maintain up-to-date software with proper patch management procedures. Organizations should also consider implementing redundant email services or backup systems to maintain business continuity during potential attack scenarios. The long-term solution involves comprehensive security architecture reviews and the adoption of more robust security frameworks that prevent buffer overflow conditions and resource exhaustion scenarios in network services.