CVE-2003-0308 in Sendmail
Summary
by MITRE
The Sendmail 8.12.3 package in Debian GNU/Linux 3.0 does not securely create temporary files, which could allow local users to gain additional privileges via (1) expn, (2) checksendmail, or (3) doublebounce.pl.
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Analysis
by VulDB Data Team • 06/28/2021
The vulnerability described in CVE-2003-0308 represents a critical security flaw in the Sendmail 8.12.3 implementation within Debian GNU/Linux 3.0 systems. This issue stems from insecure temporary file creation practices that create exploitable conditions for local privilege escalation attacks. The vulnerability specifically affects three distinct components of the Sendmail system: the expn command, checksendmail utility, and doublebounce.pl script, each providing different attack vectors for malicious users seeking to elevate their privileges.
The technical flaw manifests in the improper handling of temporary files during the execution of these Sendmail components. When these utilities process user input or perform their respective functions, they create temporary files without adequate security measures to prevent predictable naming or insecure permissions. This insecure temporary file creation pattern aligns with CWE-377, which identifies insecure temporary file creation as a significant vulnerability. The flaw allows local attackers to manipulate the temporary file creation process and potentially replace these files with malicious content that will be executed with elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader system compromise potential. Attackers exploiting these vectors can gain root access to affected systems, enabling them to modify system files, install backdoors, or establish persistent access. The three attack vectors - expn, checksendmail, and doublebounce.pl - each present unique exploitation opportunities within the Sendmail ecosystem. The expn command typically handles email address expansion, checksendmail performs various mail system checks, and doublebounce.pl manages bounce message processing, all of which can be manipulated to trigger the insecure temporary file creation behavior.
From a threat modeling perspective, this vulnerability maps to several ATT&CK techniques including privilege escalation through insecure file permissions and execution of malicious code via compromised system utilities. The attack surface is particularly concerning because these components are typically accessible to local users and may be invoked during normal mail system operations. The vulnerability represents a classic example of insecure temporary file handling that has been documented in numerous security assessments and has influenced subsequent security hardening practices. Organizations should note that this issue demonstrates the importance of proper temporary file management and the potential consequences of inadequate security controls in system utilities.
Mitigation strategies for CVE-2003-0308 should focus on immediate patching of the Sendmail package to Debian GNU/Linux 3.0 systems, as well as implementing proper temporary file creation practices in all system components. System administrators should also consider implementing file system permissions controls, monitoring for unauthorized temporary file creation, and conducting regular security audits of mail system components. The vulnerability serves as a reminder of the critical importance of secure coding practices and proper input validation in system utilities that handle user data or execute with elevated privileges.