CVE-2003-1362 in Bastille
Summary
by MITRE
Bastille B.02.00.00 of HP-UX 11.00 and 11.11 does not properly configure the (1) NOVRFY and (2) NOEXPN options in the sendmail.cf file, which could allow remote attackers to verify the existence of system users and expand defined sendmail aliases.
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Analysis
by VulDB Data Team • 06/16/2018
The vulnerability identified as CVE-2003-1362 represents a critical misconfiguration issue within the sendmail implementation on HP-UX operating systems version 11.00 and 11.11. This flaw resides in the Bastille B.02.00.00 security configuration package, which is designed to harden Unix-based systems against various cyber threats. The vulnerability specifically targets the sendmail mail transfer agent configuration, where two critical options named NOVRFY and NOEXPN are improperly disabled or absent from the sendmail.cf configuration file. These options serve as fundamental security controls that prevent certain types of user enumeration attacks against mail servers.
The technical nature of this vulnerability stems from the improper handling of two specific sendmail configuration parameters that control user account verification and alias expansion capabilities. When NOVRFY is disabled, remote attackers can exploit the sendmail service to determine whether specific user accounts exist on the system by sending verification requests that return different responses based on account existence. Similarly, when NOEXPN is disabled, attackers can enumerate sendmail aliases and distribution lists, potentially gaining insights into system user structure and organizational communication patterns. This configuration weakness creates a reconnaissance vector that allows malicious actors to gather intelligence about the target system's user base and mail infrastructure without requiring authentication or specialized tools.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with valuable reconnaissance data that can facilitate more sophisticated attacks. System administrators and security professionals can leverage this information to map out potential attack surfaces, identify high-value targets within the organization, and craft more targeted phishing campaigns or credential stuffing attacks. The vulnerability particularly affects environments where sendmail serves as the primary mail transfer agent and where user enumeration represents a significant risk to overall system security. According to CWE-200, this represents a weakness in which information is disclosed to unauthorized actors, while ATT&CK framework categorizes this as a reconnaissance technique under initial access phases.
Mitigation strategies for this vulnerability involve implementing proper sendmail configuration settings that enforce the NOVRFY and NOEXPN options within the sendmail.cf file. System administrators should ensure that these parameters are explicitly set to prevent user verification and alias expansion functionality. The recommended configuration includes adding "VRFY" and "EXPN" to the "FEATURE" line in the sendmail configuration file with appropriate security controls. Additionally, organizations should implement network segmentation to limit access to mail services, deploy intrusion detection systems to monitor for suspicious mail server activity, and conduct regular security audits to verify proper configuration of mail transfer agents. The vulnerability highlights the importance of maintaining proper security configurations as outlined in NIST SP 800-53 security controls, specifically addressing configuration management and access control requirements.