CVE-2004-1993 in Omail
Summary
by MITRE
The patch to the checklogin function in omail.pl for omail webmail 0.98.5 is incomplete, which allows remote attackers to execute arbitrary commands via shell metacharacters such as "`" (backticks) in the password.
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Analysis
by VulDB Data Team • 07/06/2025
The vulnerability identified as CVE-2004-1993 affects the omail webmail application version 0.98.5, specifically targeting the checklogin function within the omail.pl script. This represents a critical security flaw that stems from an incomplete patch implementation, creating a persistent command injection vulnerability that can be exploited by remote attackers without authentication. The flaw exists in the input validation mechanism where password parameters are not properly sanitized, allowing malicious users to inject shell metacharacters directly into the authentication process. The vulnerability manifests when an attacker supplies a password containing backtick characters which are interpreted by the system shell, enabling arbitrary command execution on the affected server. This type of vulnerability falls under CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, and represents a classic command injection flaw that has been documented extensively in cybersecurity literature. The attack vector is particularly dangerous because it operates at the authentication layer, meaning that successful exploitation can provide attackers with full control over the webmail system and potentially the underlying server infrastructure.
The technical implementation of this vulnerability exploits the fundamental weakness in the password validation process where the application fails to properly escape or filter shell metacharacters before processing user input. When a user attempts to log in with a password containing backtick characters, the system does not adequately sanitize the input before using it in shell commands, creating an opportunity for attackers to execute arbitrary system commands. The backtick character is particularly dangerous because it instructs the shell to execute the command contained within the backticks and substitute the output in place of the command. This allows attackers to chain multiple commands, potentially gaining shell access, reading sensitive files, or even escalating privileges to root level access. The incomplete patch suggests that developers may have attempted to address the vulnerability but failed to account for all possible shell metacharacters that could be used to exploit the system. This vulnerability aligns with ATT&CK technique T1059.001, which covers command and scripting interpreter, and demonstrates how authentication bypass vulnerabilities can be leveraged to achieve remote code execution.
The operational impact of CVE-2004-1993 is severe and multifaceted, as it provides attackers with complete control over the affected webmail system. Once exploited, attackers can execute any command available to the web server process, potentially leading to data exfiltration, system compromise, or even lateral movement within the network. The vulnerability affects the confidentiality, integrity, and availability of the webmail service, as attackers can modify or delete user data, access sensitive communications, or disrupt service availability. Organizations running this version of omail webmail are particularly at risk since the vulnerability exists in the core authentication logic, making it extremely difficult to detect and remediate without proper patching or input validation. The vulnerability also represents a significant risk for organizations that rely on webmail services for business communications, as it could lead to unauthorized access to sensitive corporate data, customer information, or proprietary communications. The long-term implications include potential persistent access to the compromised system, data breaches, and compliance violations that could result in significant financial and reputational damage. Security professionals should note that this vulnerability demonstrates the critical importance of thorough input validation and proper sanitization of user-supplied data in web applications, as incomplete fixes can leave systems vulnerable to exploitation. The vulnerability also highlights the need for regular security assessments and proper code review processes to identify and address such critical flaws before they can be exploited by malicious actors in the wild.