CVE-2008-1218 in Dovecot
Summary
by MITRE
Argument injection vulnerability in Dovecot 1.0.x before 1.0.13, and 1.1.x before 1.1.rc3, when using blocking passdbs, allows remote attackers to bypass the password check via a password containing TAB characters, which are treated as argument delimiters that enable the skip_password_check field to be specified.
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Analysis
by VulDB Data Team • 10/19/2024
The vulnerability described in CVE-2008-1218 represents a critical argument injection flaw in Dovecot email authentication servers that affects versions prior to 1.0.13 and 1.1.rc3. This issue specifically targets the password database (passdb) functionality where Dovecot processes authentication requests through blocking passdbs. The flaw arises from improper input validation and parsing of password values that contain tab characters, which are traditionally used as argument delimiters in command-line interfaces and system calls.
The technical implementation of this vulnerability exploits the way Dovecot handles authentication parameters when processing passwords through blocking passdbs. When a password containing tab characters is submitted during authentication, these special characters are interpreted as delimiters that separate arguments in the underlying system calls. This misinterpretation allows attackers to inject additional parameters into the authentication process, specifically manipulating the skip_password_check field. The vulnerability is classified under CWE-77 as a Command Injection, where the system incorrectly processes user-supplied data as part of command arguments rather than as literal input.
From an operational perspective, this vulnerability enables remote attackers to bypass password authentication mechanisms entirely, effectively granting unauthorized access to email accounts without proper credentials. The impact is particularly severe because it operates at the authentication layer where the system's primary security controls reside. Attackers can leverage this flaw to gain access to email services, potentially leading to data breaches, email spoofing, and further network compromise through stolen credentials. The vulnerability's remote nature means attackers do not require local system access or prior authentication to exploit the flaw, making it highly dangerous in production environments.
The exploitation of this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the credential access and privilege escalation domains. Specifically, it maps to techniques involving credential dumping and authentication bypass where attackers manipulate system authentication processes to gain unauthorized access. The vulnerability demonstrates poor input sanitization practices that violate security best practices and industry standards for secure coding. Organizations using affected Dovecot versions face significant risk of unauthorized access to their email infrastructure, particularly those with blocking passdbs configured for authentication.
Effective mitigation strategies include immediate patching of Dovecot installations to versions 1.0.13 or 1.1.rc3, which contain the necessary fixes for proper password input validation. Additionally, administrators should implement input sanitization measures that prevent tab and other special characters from being processed as argument delimiters in authentication flows. Network segmentation and monitoring for unusual authentication patterns can provide additional defense-in-depth measures. The vulnerability serves as a reminder of the critical importance of validating all user inputs and properly escaping special characters in authentication systems to prevent argument injection attacks that can compromise system security.