CVE-2002-1721 in alterMIME
Summary
by MITRE
Off-by-one error in alterMIME 0.1.10 and 0.1.11 allows remote attackers to cause a denial of service (crash) via an x-header that causes snprintf overwrite the FFGET_FILE variable with a (null) byte.
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Analysis
by VulDB Data Team • 06/09/2018
The vulnerability identified as CVE-2002-1721 represents a critical off-by-one error in the alterMIME email processing library version 0.1.10 and 0.1.11. This flaw exists within the handling of extended headers in email messages, specifically affecting how the library processes x-header fields that contain certain malformed data patterns. The issue manifests when the snprintf function encounters a particular sequence of characters that triggers an improper buffer boundary calculation, leading to memory corruption during header processing. The vulnerability falls under the category of buffer overflow conditions as classified by CWE-121, specifically involving stack-based buffer overflows that occur due to improper bounds checking in string manipulation operations.
The technical exploitation of this vulnerability occurs when remote attackers craft malicious email messages containing specially formatted x-header fields that cause the snprintf function to write beyond the allocated buffer boundaries for the FFGET_FILE variable. This improper memory management leads to a crash of the affected application or service that processes these emails through the alterMIME library. The overwrite of the FFGET_FILE variable with a null byte creates a cascading failure that can result in complete service disruption, making this a significant denial of service vulnerability that affects email servers and applications relying on this library for MIME processing. The flaw demonstrates a classic example of improper input validation and memory boundary checking that allows attackers to manipulate program execution flow through carefully constructed input data.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the reliability and availability of email infrastructure that depends on alterMIME for processing incoming messages. Email servers, spam filters, and other mail processing applications using this vulnerable library could experience frequent crashes or complete unavailability when processing maliciously crafted emails, leading to potential data loss and service interruptions that can affect thousands of users. This vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries exploit software flaws to disrupt system availability. The vulnerability is particularly concerning in environments where email systems process untrusted input from external sources, as it requires no authentication and can be exploited through simple email delivery.
Mitigation strategies for CVE-2002-1721 should focus on immediate patching of the alterMIME library to version 0.1.12 or later, which contains the necessary fixes for the off-by-one error. Organizations should implement email filtering and validation mechanisms that can detect and quarantine potentially malicious email headers before they reach the vulnerable processing components. Network administrators should consider implementing rate limiting and connection controls to prevent exploitation through automated attack vectors. Additionally, system monitoring should be enhanced to detect unusual crash patterns or service disruptions that may indicate exploitation attempts. The vulnerability serves as a reminder of the importance of proper buffer management and input validation in security-critical applications, with implications for the broader software development community regarding the necessity of thorough testing for boundary conditions in string handling operations. This issue highlights the need for defensive programming practices and adherence to secure coding standards that prevent such memory corruption vulnerabilities from reaching production environments.