CVE-1999-1015 in AppleShare IP Mail Server
Summary
by MITRE
Buffer overflow in Apple AppleShare Mail Server 5.0.3 on MacOS 8.1 and earlier allows a remote attacker to cause a denial of service (crash) via a long HELO command.
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Analysis
by VulDB Data Team • 06/05/2024
The vulnerability identified as CVE-1999-1015 represents a critical buffer overflow flaw within Apple AppleShare Mail Server version 5.0.3 that operates on MacOS 8.1 and earlier operating systems. This issue stems from inadequate input validation mechanisms within the mail server's implementation of the Simple Mail Transfer Protocol (SMTP) service, specifically during the handling of the HELO command which is fundamental to email server communication. The flaw manifests when a remote attacker crafts a maliciously long HELO command that exceeds the allocated buffer space, causing the server process to crash and resulting in a denial of service condition that disrupts legitimate email services.
The technical implementation of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The AppleShare Mail Server fails to properly validate the length of incoming HELO command parameters, allowing an attacker to inject data that exceeds the predetermined buffer size allocated for command processing. This particular implementation flaw demonstrates poor defensive programming practices and lacks proper input sanitization mechanisms that would normally prevent such memory corruption scenarios. The vulnerability operates at the application layer of the OSI model and specifically targets the SMTP protocol implementation within the AppleShare server software.
From an operational impact perspective, this vulnerability creates a significant risk for organizations relying on AppleShare Mail Server for their email infrastructure, as it enables remote attackers to perform denial of service attacks without requiring authentication or privileged access. The crash condition effectively renders the mail server unavailable to legitimate users, potentially disrupting business communications and email services for extended periods until the server is manually restarted. The vulnerability affects a specific version of AppleShare Mail Server that was prevalent during the late 1990s era, making it particularly concerning for organizations that may have legacy systems still operational. The attack vector is straightforward and requires minimal technical expertise, making it attractive to malicious actors seeking to disrupt email services.
Mitigation strategies for CVE-1999-1015 should focus on immediate remediation through software updates and patches provided by Apple to address the buffer overflow condition in the AppleShare Mail Server implementation. Organizations should implement network segmentation and access controls to limit exposure of the affected mail server to untrusted networks, while also considering the deployment of intrusion detection systems that can monitor for unusual HELO command patterns. The vulnerability demonstrates the importance of input validation and proper memory management in server applications, aligning with ATT&CK technique T1499.004 which covers network disruption through service availability attacks. Additionally, implementing proper logging and monitoring mechanisms can help detect exploitation attempts and provide early warning of potential attacks targeting this specific vulnerability. Organizations should also consider migrating away from legacy AppleShare Mail Server implementations to more modern email server solutions that incorporate better security practices and regular patch management procedures.