CVE-2007-3791 in policyd
Summary
by MITRE
Buffer overflow in the w_read function in sockets.c in Cami Sardinha and Nigel Kukard policyd before 1.81 for Postfix allows remote attackers to cause a denial of service and possibly execute arbitrary code via long SMTP commands. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 07/25/2019
The vulnerability identified as CVE-2007-3791 represents a critical buffer overflow flaw within the policyd software package, specifically affecting versions prior to 1.81. This issue resides in the w_read function located within the sockets.c file, which forms a core component of the Postfix mail server policy enforcement mechanism. The vulnerability manifests when the system processes SMTP commands, creating a scenario where remote attackers can exploit this weakness to potentially compromise system integrity and availability.
The technical implementation of this buffer overflow stems from inadequate input validation within the w_read function, which fails to properly bounds-check data received from network connections. When processing SMTP commands that exceed predetermined buffer limits, the application writes beyond allocated memory boundaries, creating opportunities for both denial of service conditions and arbitrary code execution. This flaw directly aligns with CWE-121, which categorizes buffer overflow conditions as a fundamental weakness in software design that occurs when data is written beyond the bounds of a fixed-length buffer.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system compromise. Remote attackers can leverage this weakness to cause denial of service by triggering application crashes or restarts, effectively disrupting mail services for legitimate users. More critically, the buffer overflow creates opportunities for code execution, potentially allowing malicious actors to gain unauthorized access to the system and execute arbitrary commands with the privileges of the affected service. This aligns with ATT&CK technique T1059, which describes how adversaries can execute code through command injection vulnerabilities.
The exploitation of this vulnerability requires minimal prerequisites, as it can be triggered through standard SMTP communication without requiring authentication. Attackers need only send specially crafted SMTP commands containing excessive data to the vulnerable policyd service, making this attack vector particularly dangerous for mail servers that are publicly accessible. The vulnerability affects systems where policyd is deployed as a Postfix policy daemon, making it relevant to organizations maintaining email infrastructure that relies on this specific software stack.
Mitigation strategies for CVE-2007-3791 primarily focus on immediate software updates to versions 1.81 or later where the buffer overflow has been addressed through proper input validation and bounds checking. Organizations should also implement network-level protections such as firewall rules that restrict SMTP access to trusted sources and consider deploying intrusion detection systems to monitor for suspicious command patterns. Additionally, regular security assessments should verify that all components of the mail infrastructure are properly patched and that input validation mechanisms are functioning correctly. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date software components and implementing robust input validation practices throughout system architectures.