CVE-2003-0694 in Sendmail
Summary
by MITRE
The prescan function in Sendmail 8.12.9 allows remote attackers to execute arbitrary code via buffer overflow attacks, as demonstrated using the parseaddr function in parseaddr.c.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 01/22/2025
The vulnerability identified as CVE-2003-0694 represents a critical buffer overflow flaw within the sendmail mail transfer agent version 8.12.9. This issue specifically affects the prescan function which processes email addresses during the parsing phase of message handling. The vulnerability arises from insufficient bounds checking in the parseaddr function located in parseaddr.c, creating an exploitable condition that allows remote attackers to execute arbitrary code on systems running vulnerable sendmail versions. The buffer overflow occurs when the prescan function fails to properly validate input length during address parsing operations, enabling malicious actors to overwrite adjacent memory locations through carefully crafted email addresses or header fields.
The technical exploitation of this vulnerability follows a classic buffer overflow attack pattern where attacker-controlled data exceeds the allocated buffer size in memory. When sendmail processes email addresses containing maliciously formatted input, the parseaddr function does not properly enforce buffer limits, causing data to overflow into adjacent memory regions. This memory corruption can be leveraged to overwrite return addresses, function pointers, or other critical program state information, ultimately allowing attackers to redirect program execution flow. The vulnerability is particularly dangerous because it operates at the core mail processing functionality, meaning that any email message processed by the vulnerable sendmail instance could potentially serve as an attack vector.
The operational impact of CVE-2003-0694 extends beyond simple code execution to encompass complete system compromise and potential network escalation. Remote attackers can leverage this vulnerability to gain unauthorized access to mail servers, potentially leading to data exfiltration, spam relay capabilities, or use as a foothold for further attacks within the network infrastructure. The vulnerability affects systems where sendmail 8.12.9 is deployed as the primary mail transfer agent, making it particularly relevant for enterprise email environments, web hosting providers, and any organization relying on sendmail for email processing. The attack surface is broad since email systems are typically accessible from external networks, and the vulnerability can be exploited through standard email transmission without requiring special privileges or authentication.
Security mitigations for this vulnerability primarily involve immediate patching of affected sendmail installations to versions that contain proper bounds checking and buffer overflow protections. Organizations should implement network segmentation to limit exposure of mail servers to untrusted networks and consider deploying email filtering solutions that can detect and block potentially malicious email content before it reaches vulnerable sendmail instances. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in network services. From an attack perspective, this vulnerability maps to multiple ATT&CK techniques including command and control through remote access and privilege escalation via code execution. System administrators should also implement monitoring solutions to detect unusual email processing patterns that might indicate exploitation attempts, while maintaining regular security assessments to identify and remediate similar vulnerabilities in other network services.