CVE-2004-2328 in MAILsweeper
Summary
by MITRE
Clearswift MAILsweeper for SMTP before 4.3_13 allows remote attackers to cause a denial of service (infinite loop) via an e-mail with a crafted RAR archive attached.
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Analysis
by VulDB Data Team • 06/08/2017
The vulnerability identified as CVE-2004-2328 represents a critical denial of service flaw within Clearswift MAILsweeper for SMTP versions prior to 4.3_13. This security issue manifests when the email filtering system processes maliciously crafted email messages containing RAR archive attachments. The flaw stems from improper handling of archive file structures during the scanning process, creating a condition where the system enters an infinite loop upon encountering specifically malformed RAR archives. The vulnerability operates at the application layer of the network stack, specifically targeting the email content inspection functionality that processes attachments before delivery.
The technical implementation of this vulnerability involves the MAILsweeper system's decompression routines failing to properly validate or limit the processing of RAR archive structures. When a crafted RAR file is processed, the decompression algorithm encounters malformed data that causes it to repeatedly attempt decompression without proper termination conditions. This creates an infinite loop within the application's processing thread, consuming system resources and effectively rendering the email filtering service unavailable to legitimate users. The flaw operates through the SMTP protocol's content inspection mechanisms, where email attachments are scanned for threats before being delivered to end users.
From an operational impact perspective, this vulnerability enables remote attackers to disrupt email services by simply sending a specially crafted email message containing the malicious RAR attachment. The denial of service condition affects the entire email filtering infrastructure, potentially causing widespread disruption to email communications within organizations relying on Clearswift MAILsweeper. The infinite loop consumes CPU resources and memory, leading to system instability and potential service outages that can last until the affected system is manually restarted or the malicious email is removed from processing queues. This vulnerability particularly impacts organizations that depend heavily on automated email filtering for security and compliance purposes.
The vulnerability aligns with CWE-835, which describes the weakness of an infinite loop or iteration without proper termination conditions. From an adversary perspective, this flaw maps to ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion. Organizations should implement immediate mitigations including applying the vendor-provided patch for MAILsweeper version 4.3_13 or higher, implementing email attachment filtering rules that block RAR archives entirely, and establishing monitoring for unusual CPU utilization patterns that may indicate exploitation attempts. Additionally, network administrators should consider implementing email quarantine mechanisms and regular security updates to prevent similar vulnerabilities from affecting other email security appliances. The vulnerability demonstrates the importance of proper input validation and resource management in security applications to prevent exploitation through malformed data processing.