CVE-2002-0914 in Courier MTA
Summary
by MITRE
Double Precision Courier e-mail MTA allows remote attackers to cause a denial of service (CPU consumption) via a message with an extremely large or negative value for the year, which causes a tight loop.
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Analysis
by VulDB Data Team • 04/18/2019
The vulnerability identified as CVE-2002-0914 affects the Double Precision Courier e-mail MTA implementation, representing a classic denial of service flaw that exploits improper input validation mechanisms. This vulnerability specifically targets the message processing logic where the mail transfer agent fails to adequately validate temporal data elements within email messages, creating a condition that can be exploited by remote attackers to consume excessive system resources.
The technical flaw manifests when the MTA processes email messages containing malformed year values that are either extremely large or negative numbers. These invalid temporal inputs trigger an unintended tight loop within the message parsing routine, causing the system to enter an infinite or near-infinite processing cycle. The vulnerability stems from inadequate boundary checking and input sanitization within the date parsing component of the email processing pipeline, where the software does not properly validate the range of acceptable values for temporal fields.
This operational impact results in significant CPU consumption that can effectively render the mail server unusable to legitimate users. The tight loop condition consumes system resources continuously, potentially leading to complete system exhaustion and service unavailability. Attackers can exploit this vulnerability with minimal technical expertise by simply crafting and sending a specially formatted email message containing the malicious year value, making the attack vector particularly dangerous as it requires no authentication or privileged access.
The vulnerability maps to CWE-129 Input Validation and OWASP Top Ten category A03: Injection, specifically addressing inadequate input validation and improper error handling. From an ATT&CK framework perspective, this represents a Denial of Service attack technique under the T1499.004 category, where adversaries leverage software flaws to consume system resources. The attack requires minimal prerequisites and can be executed remotely, making it particularly effective in compromising system availability.
Mitigation strategies should focus on implementing robust input validation mechanisms that enforce strict boundaries on temporal data elements, including comprehensive range checking for year values within acceptable parameters. System administrators should apply vendor-provided patches or updates that address the specific input validation flaw, while also implementing email filtering rules that can detect and block malformed messages before they reach the MTA processing engine. Network-level protections such as rate limiting and message size restrictions can provide additional defense-in-depth measures to prevent exploitation of this vulnerability.