CVE-2005-1521 in Mailutils
Summary
by MITRE
Integer overflow in the fetch_io function of the imap4d server in GNU Mailutils 0.5 and 0.6, and other versions before 0.6.90, allows remote attackers to execute arbitrary code via a partial message request with a large value in the END parameter, which leads to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 06/02/2019
The vulnerability described in CVE-2005-1521 represents a critical integer overflow flaw within the imap4d server component of GNU Mailutils versions 0.5 through 0.6.89. This issue specifically affects the fetch_io function which processes partial message requests in the IMAP4 protocol implementation. The vulnerability manifests when a remote attacker submits a malicious partial message request containing an excessively large value in the END parameter, creating a condition where integer arithmetic overflows during buffer calculations. This flaw falls under the Common Weakness Enumeration category of CWE-190, which specifically addresses integer overflow conditions that can lead to memory corruption and arbitrary code execution. The vulnerability is particularly dangerous because it allows remote attackers to manipulate the server's memory management through carefully crafted network requests.
The technical exploitation of this vulnerability occurs through a heap-based buffer overflow mechanism that arises from improper input validation in the fetch_io function. When the END parameter value exceeds the maximum representable integer value, the subsequent arithmetic operations produce incorrect buffer size calculations. This miscalculation results in the allocation of insufficient memory for the buffer, followed by attempts to write data beyond the allocated memory boundaries. The heap corruption that ensues provides attackers with a potential pathway for arbitrary code execution, as the corrupted memory can be manipulated to redirect program execution flow. The attack vector requires only network access to the affected IMAP4 server, making it particularly dangerous in environments where IMAP services are exposed to untrusted networks.
The operational impact of CVE-2005-1521 extends beyond simple denial of service conditions to encompass full system compromise capabilities. An attacker who successfully exploits this vulnerability can execute arbitrary code with the privileges of the imap4d process, potentially leading to complete system control. The vulnerability affects a wide range of GNU Mailutils installations, making it a significant concern for organizations relying on IMAP services for email handling. The flaw's presence in multiple versions of the software, from 0.5 through 0.6.89, indicates a prolonged period during which systems remained vulnerable, emphasizing the importance of timely patch management and security updates. This vulnerability demonstrates the critical nature of input validation in network services, particularly those handling user-supplied data through protocol parameters.
The recommended mitigation strategy for CVE-2005-1521 involves immediate application of the security patch released with GNU Mailutils version 0.6.90 and subsequent releases. System administrators should prioritize updating their mail server infrastructure to eliminate the integer overflow condition in the fetch_io function. Additionally, network-level protections such as firewalls and access control lists should be implemented to restrict access to IMAP services where possible, reducing the attack surface. The vulnerability highlights the necessity of robust input validation and integer overflow protection mechanisms in server-side applications, particularly those handling user-controllable parameters in network protocols. Organizations should also implement monitoring for unusual IMAP traffic patterns that might indicate exploitation attempts, as the vulnerability's exploitation often produces detectable network signatures. The ATT&CK framework categorizes this vulnerability under the technique of "Exploitation for Privilege Escalation" with potential for "Remote Code Execution" through network-based attack vectors.