CVE-2006-0141 in Internet Mail Server
Summary
by MITRE
Qualcomm Eudora Internet Mail Server (EIMS) before 3.2.8 allows remote attackers to cause a denial of service (crash) via (1) malformed NTLM authentication requests, or a malformed (2) Incoming Mail X or (3) Temporary Mail file.
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Analysis
by VulDB Data Team • 06/23/2025
The Qualcomm Eudora Internet Mail Server EIMS version 3.2.7 and earlier contains a critical vulnerability that enables remote attackers to execute denial of service attacks through three distinct vectors of exploitation. This vulnerability represents a fundamental flaw in the server's authentication and file processing mechanisms, creating pathways for adversaries to disrupt legitimate service operations without requiring authentication credentials. The vulnerability affects the server's ability to handle malformed input data, specifically targeting its NTLM authentication system and file processing components. According to CWE-20, this corresponds to an input validation weakness where the system fails to properly sanitize or reject malformed data inputs, leading to system instability and potential crashes. The vulnerability aligns with ATT&CK technique T1499.004, which involves network denial of service attacks targeting system resources through malformed requests.
The technical implementation of this vulnerability manifests through three primary attack vectors that exploit different subsystems within the EIMS server. The first vector involves malformed NTLM authentication requests that exploit weaknesses in the server's authentication handling code, causing the authentication service to crash when processing invalid or corrupted NTLM challenge-response sequences. The second vector targets incoming mail X file processing, where malformed mail headers or content structures can trigger buffer overflows or memory corruption within the mail processing pipeline. The third vector involves temporary mail file handling, where specially crafted temporary file structures can cause the server to enter an unstable state when attempting to process or store these files. Each vector represents a distinct code path that fails to properly validate input parameters before processing, creating opportunities for attackers to inject malformed data that causes unexpected behavior.
The operational impact of this vulnerability extends beyond simple service disruption, as it can result in complete server crashes that require manual intervention and system restarts to restore functionality. Organizations relying on EIMS for email services face significant operational risks, including potential loss of email communication capabilities during attack windows, increased administrative overhead for system recovery, and potential data loss from interrupted mail processing operations. The vulnerability's remote nature means that attackers can exploit it from any location without requiring physical access to the server infrastructure, making it particularly dangerous for organizations with internet-facing mail servers. The attack vectors are relatively simple to implement, requiring minimal technical expertise, which increases the likelihood of successful exploitation and makes this vulnerability attractive to a broad range of threat actors.
Mitigation strategies for this vulnerability should focus on immediate patching of the EIMS server to version 3.2.8 or later, which contains the necessary security fixes to handle malformed inputs properly. Network-level protections such as firewall rules that restrict access to the mail server ports and implementing rate limiting on authentication requests can provide additional layers of defense. Input validation controls should be implemented to filter malformed requests before they reach the vulnerable processing code paths. System administrators should monitor for unusual authentication patterns or file processing activities that might indicate exploitation attempts. The vulnerability demonstrates the importance of robust input validation practices and proper error handling in server applications, as outlined in industry security standards that emphasize defensive programming techniques to prevent resource exhaustion and system instability. Organizations should also implement regular security assessments to identify similar vulnerabilities in legacy systems and establish incident response procedures for rapid recovery from denial of service events.