CVE-2002-2423 in Sendmail
Summary
by MITRE
Sendmail 8.12.0 through 8.12.6 truncates log messages longer than 100 characters, which allows remote attackers to prevent the IP address from being logged via a long IDENT response.
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Analysis
by VulDB Data Team • 08/26/2025
The vulnerability identified as CVE-2002-2423 affects Sendmail versions 8.12.0 through 8.12.6 and represents a significant logging truncation issue that undermines the integrity of security monitoring systems. This flaw resides in the logging mechanism of the Sendmail mail transfer agent where log messages exceeding 100 characters in length are automatically truncated, creating a potential avenue for attackers to evade detection by manipulating log output. The specific context of this vulnerability involves the IDENT protocol handling within Sendmail, where the system processes user identification responses from remote systems. When a remote attacker sends an IDENT response that exceeds the 100-character limit, the logging system truncates the message, potentially removing critical information including the source IP address that would normally be recorded in the logs.
The technical implementation of this vulnerability stems from a buffer management flaw in Sendmail's logging subsystem where hardcoded limits are applied to log message lengths without proper consideration for the critical nature of the information being logged. This issue manifests specifically when Sendmail processes IDENT protocol responses, which typically contain user identification information including IP addresses and port numbers. The truncation occurs at the character level rather than at logical message boundaries, meaning that even a single character overflow beyond 100 characters can cause the entire IP address or other identifying information to be lost in the log output. This truncation behavior creates a direct path for attackers to manipulate log records by crafting IDENT responses that contain their IP address beyond the 100-character threshold, effectively masking their true source address from the logging system.
The operational impact of CVE-2002-2423 extends beyond simple logging inconvenience to represent a serious security concern that can significantly compromise network monitoring and forensic capabilities. Security administrators relying on Sendmail logs for intrusion detection, access control enforcement, or incident response activities may find their monitoring systems compromised when attackers exploit this vulnerability to hide their true IP addresses. This vulnerability directly affects the principle of audit logging and can be leveraged to bypass network security controls that depend on accurate IP address information for access decisions or threat detection. The ability to prevent IP address logging through a simple long IDENT response creates a persistent threat vector that could allow attackers to conduct malicious activities while remaining undetected by systems that depend on proper logging for security operations. This vulnerability also impacts compliance requirements that mandate complete and accurate logging for security auditing purposes, potentially leaving organizations vulnerable to regulatory violations.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to Sendmail versions 8.12.7 or later where this truncation issue has been resolved through proper buffer management and logging mechanisms. The fix typically involves implementing dynamic buffer allocation for log messages rather than relying on fixed character limits, ensuring that critical information including IP addresses is preserved regardless of message length. System administrators should also consider implementing additional monitoring controls that can detect anomalous IDENT responses or logging patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-122 Buffer Overflow in the context of improper logging and audit trail management, and represents a specific case of CWE-772 Insufficient Logging that can lead to information disclosure and security control bypass. From an ATT&CK framework perspective, this vulnerability maps to T1562.006 Impairing Defenses - Log Deletion and T1071.004 Application Layer Protocol - DNS, as it affects the reliability of logging systems that security tools depend upon for monitoring and threat detection purposes. Organizations should also conduct thorough log analysis to identify any previously undetected malicious activity that may have exploited this vulnerability to hide attacker presence, and implement comprehensive logging validation procedures to ensure that critical information is preserved in security logs regardless of message length or content.