CVE-2004-0777 in Courier-imap
Summary
by MITRE
Format string vulnerability in the auth_debug function in Courier-IMAP 1.6.0 through 2.2.1 and 3.x through 3.0.3, when login debugging (DEBUG_LOGIN) is enabled, allows remote attackers to execute arbitrary code.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/22/2024
The vulnerability described in CVE-2004-0777 represents a critical format string flaw within the Courier-IMAP server software that affects versions ranging from 1.6.0 through 2.2.1 and 3.x through 3.0.3. This issue specifically manifests within the auth_debug function when login debugging functionality is enabled through the DEBUG_LOGIN parameter. The flaw stems from improper input validation and handling of user-supplied data within the debugging output mechanism, creating a pathway for remote code execution attacks. Such vulnerabilities fall under the category of CWE-134, which specifically addresses format string vulnerabilities where format specifiers in user-controlled input are processed without proper sanitization, leading to potential exploitation of memory corruption and arbitrary code execution.
The technical exploitation of this vulnerability occurs when an attacker can manipulate the input to the auth_debug function through the login process. When DEBUG_LOGIN is enabled, the system logs detailed authentication information including user credentials and session data. The format string vulnerability arises because the application uses user-provided data directly in printf-style functions without proper validation or sanitization. This allows attackers to inject format specifiers that can read from memory locations or write to specific memory addresses, potentially leading to stack smashing, memory corruption, or direct code execution. The attack vector is particularly dangerous because it operates at the authentication layer, where attackers can leverage the vulnerability to gain unauthorized access to the mail server and potentially escalate privileges to execute arbitrary commands on the target system.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise and potential data breaches. Attackers exploiting this flaw can gain unauthorized access to email accounts, access sensitive mail data, and potentially establish persistent backdoors within the mail server infrastructure. The vulnerability affects organizations relying on Courier-IMAP for their email services, particularly those with debugging enabled in production environments. From an attack framework perspective, this vulnerability aligns with techniques documented in the MITRE ATT&CK framework under the T1078 credential access and T1059 execution tactics, where adversaries leverage legitimate credentials and system access to execute malicious code. The vulnerability's severity is compounded by the fact that debugging features are often enabled in development environments but may remain active in production systems, creating an unexpected attack surface.
Organizations should implement immediate mitigations including disabling DEBUG_LOGIN functionality in production environments, applying the official security patches released by the Courier-IMAP development team, and conducting comprehensive vulnerability assessments of their email infrastructure. The recommended remediation strategy involves upgrading to patched versions of Courier-IMAP that address the format string vulnerability in the auth_debug function, while also implementing network segmentation and monitoring to detect potential exploitation attempts. Security administrators should disable debugging features in production environments and establish proper input validation mechanisms to prevent similar vulnerabilities in other applications. The vulnerability serves as a critical reminder of the importance of secure coding practices, particularly in authentication systems where user input must be rigorously validated before being processed in any output functions, as outlined in secure coding guidelines from the OWASP project and similar industry standards.