CVE-2003-0040 in Courier MTA
Summary
by MITRE
SQL injection vulnerability in the PostgreSQL auth module for courier 0.40 and earlier allows remote attackers to execute SQL code via the user name.
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Analysis
by VulDB Data Team • 05/25/2019
The vulnerability described in CVE-2003-0040 represents a critical SQL injection flaw within the PostgreSQL authentication module of the courier email system version 0.40 and earlier. This vulnerability exists in the way the system processes user authentication requests, specifically when handling username inputs during the authentication process. The flaw allows remote attackers to inject malicious SQL code through the username parameter, potentially enabling unauthorized access to the underlying database system. The issue stems from insufficient input validation and sanitization within the authentication module, creating an avenue for attackers to manipulate the SQL queries executed by the system.
The technical implementation of this vulnerability occurs when the courier authentication module constructs SQL queries using user-provided username data without proper parameterization or input filtering. When an attacker submits a specially crafted username containing SQL injection payloads, the system processes this input directly within the SQL statement without adequate sanitization. This allows malicious SQL commands to be executed within the database context, potentially enabling attackers to retrieve sensitive information, modify database records, or even execute administrative commands on the database server. The vulnerability specifically affects the PostgreSQL backend authentication mechanism, making it particularly dangerous for systems relying on this database for email authentication services.
From an operational impact perspective, this vulnerability poses significant risks to email server security and data integrity. Attackers exploiting this flaw could gain unauthorized access to user credentials stored in the database, potentially compromising multiple email accounts and enabling further lateral movement within the network. The remote nature of the attack means that adversaries can exploit this vulnerability from anywhere on the internet without requiring local access to the system. Organizations using courier versions 0.40 and earlier face potential data breaches, unauthorized access to sensitive email communications, and possible complete database compromise. The vulnerability also affects the integrity of the authentication system, potentially allowing attackers to bypass authentication entirely and gain administrative privileges.
The vulnerability aligns with CWE-89, which specifically addresses SQL injection flaws in software applications. This classification indicates that the root cause involves improper handling of user-supplied data within SQL query construction. From an attacker's perspective, this vulnerability maps to several ATT&CK techniques including T1190 for exploitation of remote services and T1078 for valid accounts usage. The attack surface is particularly concerning given that email authentication systems are often critical infrastructure components that require robust security measures. Organizations should implement immediate patching strategies and consider network segmentation to limit the potential impact of such vulnerabilities. The remediation approach involves upgrading to courier versions that properly sanitize user inputs and implement parameterized queries to prevent SQL injection attacks. Additionally, implementing database access controls and monitoring for unusual SQL query patterns can help detect potential exploitation attempts.