CVE-2007-6101 in Ability Mail Server
Summary
by MITRE
Ability Mail Server before 2.61 allows remote authenticated users to cause a denial of service (daemon crash) via (1) malformed number list ranges in unspecified IMAP commands, and possibly (2) a blank string in unspecified messages.
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Analysis
by VulDB Data Team • 07/31/2019
The CVE-2007-6101 vulnerability affects Ability Mail Server versions prior to 2.61 and represents a significant denial of service weakness that can be exploited by authenticated remote attackers. This vulnerability specifically targets the IMAP protocol implementation within the mail server software, creating a condition where carefully crafted malformed input can cause the mail daemon to crash and restart. The flaw exists in the server's handling of input validation for number list ranges within IMAP commands, which constitutes a classic buffer overflow or input parsing vulnerability that falls under the CWE-121 category of buffer overflow conditions. The vulnerability demonstrates how improper input sanitization can lead to service disruption, which is particularly concerning in email infrastructure where availability is paramount for business operations.
The technical implementation of this vulnerability involves the mail server's inability to properly validate and process malformed number list ranges in IMAP commands, which are typically used for operations such as selecting message ranges for retrieval or manipulation. When an authenticated user sends specially crafted IMAP commands containing malformed ranges, the server's parsing logic fails to handle these edge cases gracefully, leading to memory corruption or unexpected program termination. Additionally, the vulnerability extends to potential issues with blank strings in unspecified messages, suggesting that the server's input validation is inconsistent across different message handling pathways. This dual nature of the vulnerability indicates a broader weakness in the server's input processing architecture, where different code paths for handling various message types have inconsistent security controls.
The operational impact of CVE-2007-6101 extends beyond simple service disruption to potentially affect business continuity and email accessibility for organizations relying on Ability Mail Server. A successful exploitation can cause the mail daemon to crash and restart automatically, resulting in temporary unavailability of email services for legitimate users. This type of denial of service attack can be particularly damaging in enterprise environments where email is critical for communication and business operations. The vulnerability's authenticated nature means that attackers must first obtain valid credentials, but this requirement does not significantly reduce the risk as it can be exploited by compromised accounts or insider threats. Organizations may also face compliance and audit implications due to the service disruption, as email availability is often mandated by various regulatory frameworks.
Mitigation strategies for CVE-2007-6101 should prioritize immediate patching of the Ability Mail Server to version 2.61 or later, which contains the necessary fixes for the input validation issues. Network administrators should also implement monitoring solutions to detect unusual IMAP command patterns that might indicate exploitation attempts, particularly focusing on malformed number list ranges and anomalous blank string usage. The principle of least privilege should be enforced by limiting access to IMAP services to only authorized users and implementing additional authentication layers where possible. Security teams should also consider implementing rate limiting and connection throttling mechanisms to prevent rapid exploitation attempts and ensure that any potential exploitation attempts are detected and logged for further analysis. This vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and demonstrates the importance of proper input validation as outlined in CWE-20 and CWE-121 categories. Organizations should also conduct regular security assessments of their email infrastructure to identify similar vulnerabilities in other mail server implementations and ensure comprehensive protection against similar threats.